Search Results

Search found 6723 results on 269 pages for 'django models'.

Page 268/269 | < Previous Page | 264 265 266 267 268 269  | Next Page >

  • Master Details and collectionViewSource in separate views cannot make it work.

    - by devnet247
    Hi all, I really cannot seem to make/understand how it works with separate views It all works fine if a bundle all together in a single window. I have a list of Countries-Cities-etc... When you select a country it should load it's cities. Works So I bind 3 listboxes successfully using collection sources and no codebehind more or less (just code to set the datacontext and selectionChanged). you can download the project here http://cid-9db5ae91a2948485.skydrive.live.com/self.aspx/PublicFolder/2MasterDetails.zip <Window.Resources> <CollectionViewSource Source="{Binding}" x:Key="cvsCountryList"/> <CollectionViewSource Source="{Binding Source={StaticResource cvsCountryList},Path=Cities}" x:Key="cvsCityList"/> <CollectionViewSource Source="{Binding Source={StaticResource cvsCityList},Path=Hotels}" x:Key="cvsHotelList"/> </Window.Resources> <Grid> <Grid.ColumnDefinitions> <ColumnDefinition/> <ColumnDefinition/> <ColumnDefinition/> </Grid.ColumnDefinitions> <Grid.RowDefinitions> <RowDefinition Height="Auto"/> <RowDefinition/> </Grid.RowDefinitions> <TextBlock Grid.Column="0" Grid.Row="0" Text="Countries"/> <TextBlock Grid.Column="1" Grid.Row="0" Text="Cities"/> <TextBlock Grid.Column="2" Grid.Row="0" Text="Hotels"/> <ListBox Grid.Column="0" Grid.Row="1" Name="lstCountries" IsSynchronizedWithCurrentItem="True" ItemsSource="{Binding Source={StaticResource cvsCountryList}}" DisplayMemberPath="Name" SelectionChanged="OnSelectionChanged"/> <ListBox Grid.Column="1" Grid.Row="1" Name="lstCities" IsSynchronizedWithCurrentItem="True" ItemsSource="{Binding Source={StaticResource cvsCityList}}" DisplayMemberPath="Name" SelectionChanged="OnSelectionChanged"/> <ListBox Grid.Column="2" Grid.Row="1" Name="lstHotels" ItemsSource="{Binding Source={StaticResource cvsHotelList}}" DisplayMemberPath="Name" SelectionChanged="OnSelectionChanged"/> </Grid> Does not work I am trying to implement the same using a view for each eg(LeftSideMasterControl -RightSideDetailsControls) However I cannot seem to make them bind. Can you help? I would be very grateful so that I can understand how you communicate between userControls You can download the project here. http://cid-9db5ae91a2948485.skydrive.live.com/self.aspx/PublicFolder/2MasterDetails.zip I have as follows LeftSideMasterControl.xaml <Grid> <ListBox Name="lstCountries" SelectionChanged="OnSelectionChanged" DisplayMemberPath="Name" ItemsSource="{Binding Countries}"/> </Grid> RightViewDetailsControl.xaml MainView.xaml <CollectionViewSource Source="{Binding}" x:Key="cvsCountryList"/> <CollectionViewSource Source="{Binding Source={StaticResource cvsCountryList},Path=Cities}" x:Key="cvsCityList"/> </UserControl.Resources> <Grid> <Grid.ColumnDefinitions> <ColumnDefinition/> <ColumnDefinition Width="3*"/> </Grid.ColumnDefinitions> <Views:LeftViewMasterControl x:Name="leftSide" Margin="5" Content="{Binding Source=}"/> <GridSplitter Grid.Column="0" Grid.Row="0" Background="LightGray"/> <Views:RightViewDetailsControl Grid.Column="1" x:Name="RightSide" Margin="5"/> </Grid> ViewModels public class CountryListVM : ViewModelBase { public CountryListVM() { Countries = new ObservableCollection<CountryVM>(); } public ObservableCollection<CountryVM> Countries { get; set; } private RelayCommand _loadCountriesCommand; public ICommand LoadCountriesCommand { get { return _loadCountriesCommand ?? (_loadCountriesCommand = new RelayCommand(x => LoadCountries(), x => CanLoadCountries)); } } private static bool CanLoadCountries { get { return true; } } private void LoadCountries() { var countryList = Repository.GetCountries(); foreach (var country in countryList) { Countries.Add(new CountryVM { Name = country.Name }); } } } public class CountryVM : ViewModelBase { private string _name; public string Name { get { return _name; } set { _name = value; OnPropertyChanged("Name"); } } } public class CityListVM : ViewModelBase { private CountryVM _selectedCountry; public CityListVM(CountryVM country) { SelectedCountry = country; Cities = new ObservableCollection<CityVM>(); } public ObservableCollection<CityVM> Cities { get; set; } public CountryVM SelectedCountry { get { return _selectedCountry; } set { _selectedCountry = value; OnPropertyChanged("SelectedCountry"); } } private RelayCommand _loadCitiesCommand; public ICommand LoadCitiesCommand { get { return _loadCitiesCommand ?? (_loadCitiesCommand = new RelayCommand(x => LoadCities(), x => CanLoadCities)); } } private static bool CanLoadCities { get { return true; } } private void LoadCities() { var cities = Repository.GetCities(SelectedCountry.Name); foreach (var city in cities) { Cities.Add(new CityVM() { Name = city.Name }); } } } public class CityVM : ViewModelBase { private string _name; public string Name { get { return _name; } set { _name = value; OnPropertyChanged("Name"); } } } Models ========= public class Country { public Country() { Cities = new ObservableCollection<City>(); } public string Name { get; set; } public ObservableCollection<City> Cities { get; set; } } public class City { public City() { Hotels = new ObservableCollection<Hotel>(); } public string Name { get; set; } public ObservableCollection<Hotel> Hotels { get; set; } } public class Hotel { public string Name { get; set; } }

    Read the article

  • Problem with jQuery and ASP.Net MVC

    - by robert_d
    I have a problem with jQuery, here is how my web app works Search web page which contains a form and jQuery script posts data to Search() action in Home controller after user clicks button1 button. Search.aspx: <%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<GLSChecker.Models.WebGLSQuery>" %> <asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server"> Title </asp:Content> <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"> <h2>Search</h2> <% Html.EnableClientValidation(); %> <% using (Html.BeginForm()) {%> <fieldset> <div class="editor-label"> <%: Html.LabelFor(model => model.Url) %> </div> <div class="editor-field"> <%: Html.TextBoxFor(model => model.Url, new { size = "50" } ) %> <%: Html.ValidationMessageFor(model => model.Url) %> </div> <div class="editor-label"> <%: Html.LabelFor(model => model.Location) %> </div> <div class="editor-field"> <%: Html.TextBoxFor(model => model.Location, new { size = "50" } ) %> <%: Html.ValidationMessageFor(model => model.Location) %> </div> <div class="editor-label"> <%: Html.LabelFor(model => model.KeywordLines) %> </div> <div class="editor-field"> <%: Html.TextAreaFor(model => model.KeywordLines, 10, 60, null)%> <%: Html.ValidationMessageFor(model => model.KeywordLines)%> </div> <p> <input id ="button1" type="submit" value="Search" /> </p> </fieldset> <% } %> <script src="../../Scripts/jquery-1.4.1.js" type="text/javascript"></script> <script type="text/javascript"> jQuery("#button1").click(function (e) { window.setInterval(refreshResult, 5000); }); function refreshResult() { jQuery("#divResult").load("/Home/Refresh"); } </script> <div id="divResult"> </div> </asp:Content> [HttpPost] public ActionResult Search(WebGLSQuery queryToCreate) { if (!ModelState.IsValid) return View("Search"); queryToCreate.Remote_Address = HttpContext.Request.ServerVariables["REMOTE_ADDR"]; Session["Result"] = null; SearchKeywordLines(queryToCreate); Thread.Sleep(15000); return View("Search"); }//Search() After button1 button is clicked the above script from Search web page runs Search() action in controller runs for longer period of time. I simulate this in testing by putting Thread.Sleep(15000); in Search()action. 5 sec. after Submit button was pressed, the above jQuery script calls Refresh() action in Home controller. public ActionResult Refresh() { ViewData["Result"] = DateTime.Now; return PartialView(); } Refresh() renders this partial <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl" % <%= ViewData["Result"] % The problem is that in Internet Explorer 8 there is only one request to /Home/Refresh; in Firefox 3.6.3 all requests to /Home/Refresh are made but nothing is displayed on the web page. I would be grateful for helpful suggestions.

    Read the article

  • Html.BeginForm() not rendering properly

    - by Taskos George
    While searching in stackoverflow the other questions didn't exactly helped in my situation. How it would be possible to debug such an error like the one that the Html.BeginForm does not properly rendered to the page. I use this code @model ExtremeProduction.Models.SelectUserGroupsViewModel @{ ViewBag.Title = "User Groups"; } <h2>Groups for user @Html.DisplayFor(model => model.UserName)</h2> <hr /> @using (Html.BeginForm("UserGroups", "Account", FormMethod.Post, new { encType = "multipart/form-data", id = "userGroupsForm" })) { @Html.AntiForgeryToken() <div class="form-horizontal"> @Html.ValidationSummary(true) <div class="form-group"> <div class="col-md-10"> @Html.HiddenFor(model => model.UserName) </div> </div> <h4>Select Group Assignments</h4> <br /> <hr /> <table> <tr> <th> Select </th> <th> Group </th> </tr> @Html.EditorFor(model => model.Groups) </table> <br /> <hr /> <div class="form-group"> <div class="col-md-offset-2 col-md-10"> <input type="submit" value="Save" class="btn btn-default" /> </div> </div> </div> } <div> @Html.ActionLink("Back to List", "Index") </div> EDIT: Added the Model // Wrapper for SelectGroupEditorViewModel to select user group membership: public class SelectUserGroupsViewModel { public string UserName { get; set; } public string FirstName { get; set; } public string LastName { get; set; } public List<SelectGroupEditorViewModel> Groups { get; set; } public SelectUserGroupsViewModel() { this.Groups = new List<SelectGroupEditorViewModel>(); } public SelectUserGroupsViewModel(ApplicationUser user) : this() { this.UserName = user.UserName; this.FirstName = user.FirstName; this.LastName = user.LastName; var Db = new ApplicationDbContext(); // Add all available groups to the public list: var allGroups = Db.Groups; foreach (var role in allGroups) { // An EditorViewModel will be used by Editor Template: var rvm = new SelectGroupEditorViewModel(role); this.Groups.Add(rvm); } // Set the Selected property to true where user is already a member: foreach (var group in user.Groups) { var checkUserRole = this.Groups.Find(r => r.GroupName == group.Group.Name); checkUserRole.Selected = true; } } } // Used to display a single role group with a checkbox, within a list structure: public class SelectGroupEditorViewModel { public SelectGroupEditorViewModel() { } public SelectGroupEditorViewModel(Group group) { this.GroupName = group.Name; this.GroupId = group.Id; } public bool Selected { get; set; } [Required] public int GroupId { get; set; } public string GroupName { get; set; } } public class Group { public Group() { } public Group(string name) : this() { Roles = new List<ApplicationRoleGroup>(); Name = name; } [Key] [Required] public virtual int Id { get; set; } public virtual string Name { get; set; } public virtual ICollection<ApplicationRoleGroup> Roles { get; set; } } ** EDIT ** And I get this form http://i834.photobucket.com/albums/zz268/gtas/formmine_zpsf6470e02.png I should receive a form like the one that I copied the code like this http://i834.photobucket.com/albums/zz268/gtas/formcopied_zpsdb2f129e.png Any ideas where or how to look the source of evil that makes my life hard for some time now?

    Read the article

  • Rails multiple select box issue for search

    - by Reido
    First off here is my model, controller, view: My model, this is where I have my search code:--------------------------- def self.find_by_lcc(params) where = [] where << "category = 'Land'" unless params[:mls].blank? where << "mls = :mls" end unless params[:county].blank? where << "county = :county" end unless params[:acreage_range].blank? where << "acreage_range = :acreage_range" end unless params[:landtype].blank? where << "landtype = :landtype" end unless params[:price_range].blank? where << "price_range = :price_range" end if where.empty? [] else find(:all, :conditions => [where.join(" AND "), params], :order => "county, price desc") end end My controller:---------------- def land @counties = ['Adams', 'Alcorn', 'Amite', 'Attala'] @title = "Browse" return if params[:commit].nil? @properties = Property.find_by_lcc(params) else 'No properties were found' render :action = 'land_table' end My View: ---------------------- <table width="900"> <tr> <td> <% form_tag({ :action => "land" }, :method => "get") do %> <fieldset> <legend>Search our Land Properties</legend> <div class="form_row"><p>&nbsp;</p></div> <div class="form_row"> <label for="mls">MLS Number:</label>&nbsp; <%= text_field_tag 'mls', params[:mls] %> </div> <div class="form_row"> <label for "county"><font color="#ff0000">*County:</font></label>&nbsp; <%= select_tag "county", options_for_select(@counties), :multiple => true, :size => 6 %> </div> <div class="form_row"> <label for "acreage_range">Acreage:</label>&nbsp; <%= select_tag "acreage_range", options_for_select([['All',''],['1-10','1-10'],['11-25','11-25'],['26-50','26-50'],['51-100','51-100']]) %> </div> <div class="form_row"> <label for "landtype">Type:</label>&nbsp; <%= select_tag "landtype", options_for_select([['All',''],['Waterfront','Waterfront'],['Wooded','Wooded'],['Pasture','Pasture'],['Woods/Pasture','Woods/Pasture'],['Lot','Lot']]) %> </div> <div class="form_row"> <label for="price_range"><font color="#ff0000">*Price:</font></label>&nbsp; <%= select_tag "price_range", options_for_select([['All',''],['0-1,000','0-1,000'],['1,001-10,000','1,001-10,000'],['10,001-50,000','10,001-50,000'],['50,001-100,000','50,001-100,000'],['100,001-150,000']])%> </div> <input type="text" style="display: none;" disabled="disabled" size="1" /> <%= submit_tag "Search", :class => "submit" %> </fieldset> <% end%> </td> </tr> </table> The search works fine until I add ", :multiple = true, :size = 6" to make the county field multiple select. Then I get the error: Processing PublicController#land (for 65.0.81.83 at 2010-04-01 13:11:30) [GET] Parameters: {"acreage_range"=>"", "commit"=>"Search", "county"=>["Adams", "Amite"], "landtype"=>"", "price_range"=>"", "mls"=>""} ActiveRecord::StatementInvalid (Mysql::Error: Operand should contain 1 column(s): SELECT * FROM `properties` WHERE (category = 'Land' AND county = 'Adams','Amite') ORDER BY county, price desc): app/models/property.rb:93:in `find_by_lcc' app/controllers/public_controller.rb:84:in `land' /usr/lib/ruby/1.8/thread.rb:135:in `synchronize' fcgi (0.8.7) lib/fcgi.rb:117:in `session' fcgi (0.8.7) lib/fcgi.rb:104:in `each_request' fcgi (0.8.7) lib/fcgi.rb:36:in `each' dispatch.fcgi:24 I've tried to make the county, acreage_range, and price_range fields into multiple select boxes numerous ways, but can not get any method to work correctly. Any help would be greatly appreciated. Thanks,

    Read the article

  • setIncludesSubentities: in an NSFetchRequest is broken for entities across multiple persistent store

    - by SG
    Prior art which doesn't quite address this: http://stackoverflow.com/questions/1774359/core-data-migration-error-message-model-does-not-contain-configuration-xyz I have narrowed this down to a specific issue. It takes a minute to set up, though; please bear with me. The gist of the issue is that a persistentStoreCoordinator (apparently) cannot preserve the part of an object graph where a managedObject is marked as a subentity of another when they are stored in different files. Here goes... 1) I have 2 xcdatamodel files, each containing a single entity. In runtime, when the managed object model is constructed, I manually define one entity as subentity of another using setSubentities:. This is because defining subentities across multiple files in the editor is not supported yet. I then return the complete model with modelByMergingModels. //Works! [mainEntity setSubentities:canvasEntities]; NSLog(@"confirm %@ is super for %@", [[[canvasEntities lastObject] superentity] name], [[canvasEntities lastObject] name]); //Output: "confirm Note is super for Browser" 2) I have modified the persistentStoreCoordinator method so that it sets a different store for each entity. Technically, it uses configurations, and each entity has one and only one configuration defined. //Also works! for ( NSString *configName in [[HACanvasPluginManager shared].registeredCanvasTypes valueForKey:@"viewControllerClassName"] ) { storeUrl = [NSURL fileURLWithPath:[[self applicationDocumentsDirectory] stringByAppendingPathComponent:[configName stringByAppendingPathExtension:@"sqlite"]]]; //NSLog(@"entities for configuration '%@': %@", configName, [[[self managedObjectModel] entitiesForConfiguration:configName] valueForKey:@"name"]); //Output: "entities for configuration 'HATextCanvasController': (Note)" //Output: "entities for configuration 'HAWebCanvasController': (Browser)" if (![persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:configName URL:storeUrl options:options error:&error]) //etc 3) I have a fetchRequest set for the parent entity, with setIncludesSubentities: and setAffectedStores: just to be sure we get both 1) and 2) covered. When inserting objects of either entity, they both are added to the context and they both are fetched by the fetchedResultsController and displayed in the tableView as expected. // Create the fetch request for the entity. NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; [fetchRequest setEntity:entity]; [fetchRequest setIncludesSubentities:YES]; //NECESSARY to fetch all canvas types [fetchRequest setSortDescriptors:sortDescriptors]; [fetchRequest setFetchBatchSize:20]; // Set the batch size to a suitable number. [fetchRequest setAffectedStores:[[managedObjectContext persistentStoreCoordinator] persistentStores]]; [fetchRequest setReturnsObjectsAsFaults:NO]; Here is where it starts misbehaving: after closing and relaunching the app, ONLY THE PARENT ENTITY is fetched. If I change the entity of the request using setEntity: to the entity for 'Note', all notes are fetched. If I change it to the entity for 'Browser', all the browsers are fetched. Let me reiterate that during the run in which an object is first inserted into the context, it will appear in the list. It is only after save and relaunch that a fetch request fails to traverse the hierarchy. Therefore, I can only conclude that it is the storage of the inheritance that is the problem. Let's recap why: - Both entities can be created, inserted into the context, and viewed, so the model is working - Both entities can be fetched with a single request, so the inheritance is working - I can confirm that the files are being stored separately and objects are going into their appropriate stores, so saving is working - Launching the app with either entity set for the request works, so retrieval from the store is working - This also means that traversing different stores with the request is working - By using a single store instead of multiple, the problem goes away completely, so creating, storing, fetching, viewing etc is working correctly. This leaves only one culprit (to my mind): the inheritance I'm setting with setSubentities: is effective only for objects creating during the session. Either objects/entities are being stored stripped of the inheritance info, or entity inheritance as defined programmatically only applies to new instances, or both. Either of these is unacceptable. Either it's a bug or I am way, way off course. I have been at this every which way for two days; any insight is greatly appreciated. The current workaround - just using a single store - works completely, except it won't be future-proof in the event that I remove one of the models from the app etc. It also boggles the mind because I can't see why you would have all this infrastructure for storing across multiple stores and for setting affected stores in fetch requests if it by core definition (of setSubentities:) doesn't work.

    Read the article

  • Custom validation works in development but not in unit test

    - by Geolev
    I want to validate that at least one of two columns have a value in my model. I found somewhere on the web that I could create a custom validator as follows: # Check for the presence of one or another field: # :validates_presence_of_at_least_one_field :last_name, :company_name - would require either last_name or company_name to be filled in # also works with arrays # :validates_presence_of_at_least_one_field :email, [:name, :address, :city, :state] - would require email or a mailing type address module ActiveRecord module Validations module ClassMethods def validates_presence_of_at_least_one_field(*attr_names) msg = attr_names.collect {|a| a.is_a?(Array) ? " ( #{a.join(", ")} ) " : a.to_s}.join(", ") + "can't all be blank. At least one field must be filled in." configuration = { :on => :save, :message => msg } configuration.update(attr_names.extract_options!) send(validation_method(configuration[:on]), configuration) do |record| found = false attr_names.each do |a| a = [a] unless a.is_a?(Array) found = true a.each do |attr| value = record.respond_to?(attr.to_s) ? record.send(attr.to_s) : record[attr.to_s] found = !value.blank? end break if found end record.errors.add_to_base(configuration[:message]) unless found end end end end end I put this in a file called lib/acs_validator.rb in my project and added "require 'acs_validator'" to my environment.rb. This does exactly what I want. It works perfectly when I manually test it in the development environment but when I write a unit test it breaks my test environment. This is my unit test: require 'test_helper' class CustomerTest < ActiveSupport::TestCase # Replace this with your real tests. test "the truth" do assert true end test "customer not valid" do puts "customer not valid" customer = Customer.new assert !customer.valid? assert customer.errors.invalid?(:subdomain) assert_equal "Company Name and Last Name can't both be blank.", customer.errors.on(:contact_lname) end end This is my model: class Customer < ActiveRecord::Base validates_presence_of :subdomain validates_presence_of_at_least_one_field :customer_company_name, :contact_lname, :message => "Company Name and Last Name can't both be blank." has_one :service_plan end When I run the unit test, I get the following error: DEPRECATION WARNING: Rake tasks in vendor/plugins/admin_data/tasks, vendor/plugins/admin_data/tasks, and vendor/plugins/admin_data/tasks are deprecated. Use lib/tasks instead. (called from /usr/lib/ruby/gems/1.8/gems/rails-2.3.8/lib/tasks/rails.rb:10) Couldn't drop acs_test : #<ActiveRecord::StatementInvalid: PGError: ERROR: database "acs_test" is being accessed by other users DETAIL: There are 1 other session(s) using the database. : DROP DATABASE IF EXISTS "acs_test"> acs_test already exists NOTICE: CREATE TABLE will create implicit sequence "customers_id_seq" for serial column "customers.id" NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "customers_pkey" for table "customers" NOTICE: CREATE TABLE will create implicit sequence "service_plans_id_seq" for serial column "service_plans.id" NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "service_plans_pkey" for table "service_plans" /usr/bin/ruby1.8 -I"lib:test" "/usr/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake/rake_test_loader.rb" "test/unit/customer_test.rb" "test/unit/service_plan_test.rb" "test/unit/helpers/dashboard_helper_test.rb" "test/unit/helpers/customers_helper_test.rb" "test/unit/helpers/service_plans_helper_test.rb" /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.8/lib/active_record/base.rb:1994:in `method_missing_without_paginate': undefined method `validates_presence_of_at_least_one_field' for #<Class:0xb7076bd0> (NoMethodError) from /usr/lib/ruby/gems/1.8/gems/will_paginate-2.3.12/lib/will_paginate/finder.rb:170:in `method_missing' from /home/george/projects/advancedcomfortcs/app/models/customer.rb:3 from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require' from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:31:in `require' from /usr/lib/ruby/gems/1.8/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:158:in `require' from /usr/lib/ruby/gems/1.8/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:265:in `require_or_load' from /usr/lib/ruby/gems/1.8/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:224:in `depend_on' from /usr/lib/ruby/gems/1.8/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:136:in `require_dependency' from /usr/lib/ruby/gems/1.8/gems/rails-2.3.8/lib/initializer.rb:414:in `load_application_classes' from /usr/lib/ruby/gems/1.8/gems/rails-2.3.8/lib/initializer.rb:413:in `each' from /usr/lib/ruby/gems/1.8/gems/rails-2.3.8/lib/initializer.rb:413:in `load_application_classes' from /usr/lib/ruby/gems/1.8/gems/rails-2.3.8/lib/initializer.rb:411:in `each' from /usr/lib/ruby/gems/1.8/gems/rails-2.3.8/lib/initializer.rb:411:in `load_application_classes' from /usr/lib/ruby/gems/1.8/gems/rails-2.3.8/lib/initializer.rb:197:in `process' from /usr/lib/ruby/gems/1.8/gems/rails-2.3.8/lib/initializer.rb:113:in `send' from /usr/lib/ruby/gems/1.8/gems/rails-2.3.8/lib/initializer.rb:113:in `run' from /home/george/projects/advancedcomfortcs/config/environment.rb:9 from ./test/test_helper.rb:2:in `require' from ./test/test_helper.rb:2 from ./test/unit/customer_test.rb:1:in `require' from ./test/unit/customer_test.rb:1 from /usr/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake/rake_test_loader.rb:5:in `load' from /usr/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake/rake_test_loader.rb:5 from /usr/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake/rake_test_loader.rb:5:in `each' from /usr/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake/rake_test_loader.rb:5 rake aborted! Command failed with status (1): [/usr/bin/ruby1.8 -I"lib:test" "/usr/lib/ru...] (See full trace by running task with --trace) It seems to have stepped on will_paginate somehow. Does anyone have any suggestions? Is there another way to do the validation I'm attempting to do? Thanks, George

    Read the article

  • Sorting/Paginating/Filtering Complex Multi-AR Object Tables in Rails

    - by Matt Rogish
    I have a complex table pulled from a multi-ActiveRecord object array. This listing is a combined display of all of a particular user's "favorite" items (songs, messages, blog postings, whatever). Each of these items is a full-fledged AR object. My goal is to present the user with a simplified search, sort, and pagination interface. The user need not know that the Song has a singer, and that the Message has an author -- to the end user both entries in the table will be displayed as "User". Thus, the search box will simply be a dropdown list asking them which to search on (User name, created at, etc.). Internally, I would need to convert that to the appropriate object search, combine the results, and display. I can, separately, do pagination (mislav will_paginate), sorting, and filtering, but together I'm having some problems combining them. For example, if I paginate the combined list of items, the pagination plugin handles it just fine. It is not efficient since the pagination is happening in the app vs. the DB, but let's assume the intended use-case would indicate the vast majority of the users will have less than 30 favorited items and all other behavior, server capabilities, etc. indicates this will not be a bottleneck. However, if I wish to sort the list I cannot sort it via the pagination plugin because it relies on the assumption that the result set is derived from a single SQL query, and also that the field name is consistent throughout. Thus, I must sort the merged array via ruby, e.g. @items.sort_by{ |i| i.whatever } But, since the items do not share common names, I must first interrogate the object and then call the correct sort by. For example, if the user wishes to sort by user name, if the sorted object is a message, I sort by author but if the object is a song, I sort by singer. This is all very gross and feels quite un-ruby-like. This same problem comes into play with the filter. If the user filters on the "parent item" (the message's thread, the song's album), I must translate that to the appropriate collection object method. Also gross. This is not the exact set-up but is close enough. Note that this is a legacy app so changing it is quite difficult, although not impossible. Also, yes there is some DRY that can be done, but don't focus on the style or elegance of the following code. Style/elegance of the SOLUTION is important, however! :D models: class User < ActiveRecord::Base ... has_and_belongs_to_many :favorite_messages, :class_name => "Message" has_and_belongs_to_many :favorite_songs, :class_name => "Song" has_many :authored_messages, :class_name => "Message" has_many :sung_songs, :class_name => "Song" end class Message < ActiveRecord::Base has_and_belongs_to_many :favorite_messages belongs_to :author, :class_name => "User" belongs_to :thread end class Song < ActiveRecord::Base has_and_belongs_to_many :favorite_songs belongs_to :singer, :class_name => "User" belongs_to :album end controller: def show u = User.find 123 @items = Array.new @items << u.favorite_messages @items << u.favorite_songs # etc. etc. @items.flatten! @items = @items.sort_by{ |i| i.created_at } @items = @items.paginate :page => params[:page], :per_page => 20 end def search # Assume user is searching for username like 'Bob' u = User.find 123 @items = Array.new @items << u.favorite_messages.find( :all, :conditions => "LOWER( author ) LIKE LOWER('%bob%')" ) @items << u.favorite_songs.find( :all, :conditions => "LOWER( singer ) LIKE ... " ) # etc. etc. @items.flatten! @items = @items.sort_by{ |i| determine appropriate sorting based on user selection } @items = @items.paginate :page => params[:page], :per_page => 20 end view: #index.html.erb ... <table> <tr> <th>Title (sort ASC/DESC links)</th> <th>Created By (sort ASC/DESC links))</th> <th>Collection Title (sort ASC/DESC links)</th> <th>Created At (sort ASC/DESC links)</th> </tr> <% @items.each |item| do %> <%= render { :partial => "message", :locals => item } if item.is_a? Message %> <%= render { :partial => "song", :locals => item } if item.is_a? Song %> <%end%> ... </table> #message.html.erb # shorthand, not real ruby print out message title, author name, thread title, message created at #song.html.erb # shorthand print out song title, singer name, album title, song created at

    Read the article

  • How to implement Cocoa copyWithZone on derived object in MonoMac C#?

    - by Justin Aquadro
    I'm currently porting a small Winforms-based .NET application to use a native Mac front-end with MonoMac. The application has a TreeControl with icons and text, which does not exist out of the box in Cocoa. So far, I've ported almost all of the ImageAndTextCell code in Apple's DragNDrop example: https://developer.apple.com/library/mac/#samplecode/DragNDropOutlineView/Listings/ImageAndTextCell_m.html#//apple_ref/doc/uid/DTS40008831-ImageAndTextCell_m-DontLinkElementID_6, which is assigned to an NSOutlineView as a custom cell. It seems to be working almost perfectly, except that I have not figured out how to properly port the copyWithZone method. Unfortunately, this means the internal copies that NSOutlineView is making do not have the image field, and it leads to the images briefly vanishing during expand and collapse operations. The objective-c code in question is: - (id)copyWithZone:(NSZone *)zone { ImageAndTextCell *cell = (ImageAndTextCell *)[super copyWithZone:zone]; // The image ivar will be directly copied; we need to retain or copy it. cell->image = [image retain]; return cell; } The first line is what's tripping me up, as MonoMac does not expose a copyWithZone method, and I don't know how to otherwise call it. Update Based on current answers and additional research and testing, I've come up with a variety of models for copying an object. static List<ImageAndTextCell> _refPool = new List<ImageAndTextCell>(); // Method 1 static IntPtr selRetain = Selector.GetHandle ("retain"); [Export("copyWithZone:")] public virtual NSObject CopyWithZone(IntPtr zone) { ImageAndTextCell cell = new ImageAndTextCell() { Title = Title, Image = Image, }; Messaging.void_objc_msgSend (cell.Handle, selRetain); return cell; } // Method 2 [Export("copyWithZone:")] public virtual NSObject CopyWithZone(IntPtr zone) { ImageAndTextCell cell = new ImageAndTextCell() { Title = Title, Image = Image, }; _refPool.Add(cell); return cell; } [Export("dealloc")] public void Dealloc () { _refPool.Remove(this); this.Dispose(); } // Method 3 static IntPtr selRetain = Selector.GetHandle ("retain"); [Export("copyWithZone:")] public virtual NSObject CopyWithZone(IntPtr zone) { ImageAndTextCell cell = new ImageAndTextCell() { Title = Title, Image = Image, }; _refPool.Add(cell); Messaging.void_objc_msgSend (cell.Handle, selRetain); return cell; } // Method 4 static IntPtr selRetain = Selector.GetHandle ("retain"); static IntPtr selRetainCount = Selector.GetHandle("retainCount"); [Export("copyWithZone:")] public virtual NSObject CopyWithZone (IntPtr zone) { ImageAndTextCell cell = new ImageAndTextCell () { Title = Title, Image = Image, }; _refPool.Add (cell); Messaging.void_objc_msgSend (cell.Handle, selRetain); return cell; } public void PeriodicCleanup () { List<ImageAndTextCell> markedForDelete = new List<ImageAndTextCell> (); foreach (ImageAndTextCell cell in _refPool) { uint count = Messaging.UInt32_objc_msgSend (cell.Handle, selRetainCount); if (count == 1) markedForDelete.Add (cell); } foreach (ImageAndTextCell cell in markedForDelete) { _refPool.Remove (cell); cell.Dispose (); } } // Method 5 static IntPtr selCopyWithZone = Selector.GetHandle("copyWithZone:"); [Export("copyWithZone:")] public virtual NSObject CopyWithZone(IntPtr zone) { IntPtr copyHandle = Messaging.IntPtr_objc_msgSendSuper_IntPtr(SuperHandle, selCopyWithZone, zone); ImageAndTextCell cell = new ImageAndTextCell(copyHandle) { Image = Image, }; _refPool.Add(cell); return cell; } Method 1: Increases the retain count of the unmanaged object. The unmanaged object will persist persist forever (I think? dealloc never called), and the managed object will be harvested early. Seems to be lose-lose all-around, but runs in practice. Method 2: Saves a reference of the managed object. The unmanaged object is left alone, and dealloc appears to be invoked at a reasonable time by the caller. At this point the managed object is released and disposed. This seems reasonable, but on the downside the base type's dealloc won't be run (I think?) Method 3: Increases the retain count and saves a reference. Unmanaged and managed objects leak forever. Method 4: Extends Method 3 by adding a cleanup function that is run periodically (e.g. during Init of each new ImageAndTextCell object). The cleanup function checks the retain counts of the stored objects. A retain count of 1 means the caller has released it, so we should as well. Should eliminate leaking in theory. Method 5: Attempt to invoke the copyWithZone method on the base type, and then construct a new ImageAndTextView object with the resulting handle. Seems to do the right thing (the base data is cloned). Internally, NSObject bumps the retain count on objects constructed like this, so we also use the PeriodicCleanup function to release these objects when they're no longer used. Based on the above, I believe Method 5 is the best approach since it should be the only one that results in a truly correct copy of the base type data, but I don't know if the approach is inherently dangerous (I am also making some assumptions about the underlying implementation of NSObject). So far nothing bad has happened "yet", but if anyone is able to vet my analysis then I would be more confident going forward.

    Read the article

  • Design advice for avoiding change in several classes

    - by Anders Svensson
    Hi, I'm trying to figure out how to design a small application more elegantly, and make it more resistant to change. Basically it is a sort of project price calculator, and the problem is that there are many parameters that can affect the pricing. I'm trying to avoid cluttering the code with a lot of if-clauses for each parameter, but still I have e.g. if-clauses in two places checking for the value of the size parameter. I have the Head First Design Patterns book, and have tried to find ideas there, but the closest I got was the decorator pattern, which has an example where starbuzz coffee sets prices depending first on condiments added, and then later in an exercise by adding a size parameter (Tall, Grande, Venti). But that didn't seem to help, because adding that parameter still seemed to add if-clause complexity in a lot of places (and this being an exercise they didn't explain that further). What I am trying to avoid is having to change several classes if a parameter were to change or a new parameter added, or at least change in as few places as possible (there's some fancy design principle word for this that I don't rememeber :-)). Here below is the code. Basically it calculates the price for a project that has the tasks "Writing" and "Analysis" with a size parameter and different pricing models. There will be other parameters coming in later too, like "How new is the product?" (New, 1-5 years old, 6-10 years old), etc. Any advice on the best design would be greatly appreciated, whether a "design pattern" or just good object oriented principles that would make it resistant to change (e.g. adding another size, or changing one of the size values, and only have to change in one place rather than in several if-clauses): public class Project { private readonly int _numberOfProducts; protected Size _size; public Task Analysis { get; set; } public Task Writing { get; set; } public Project(int numberOfProducts) { _numberOfProducts = numberOfProducts; _size = GetSize(); Analysis = new AnalysisTask(numberOfProducts, _size); Writing = new WritingTask(numberOfProducts, _size); } private Size GetSize() { if (_numberOfProducts <= 2) return Size.small; if (_numberOfProducts <= 8) return Size.medium; return Size.large; } public double GetPrice() { return Analysis.GetPrice() + Writing.GetPrice(); } } public abstract class Task { protected readonly int _numberOfProducts; protected Size _size; protected double _pricePerHour; protected Dictionary<Size, int> _hours; public abstract int TotalHours { get; } public double Price { get; set; } protected Task(int numberOfProducts, Size size) { _numberOfProducts = numberOfProducts; _size = size; } public double GetPrice() { return _pricePerHour * TotalHours; } } public class AnalysisTask : Task { public AnalysisTask(int numberOfProducts, Size size) : base(numberOfProducts, size) { _pricePerHour = 850; _hours = new Dictionary<Size, int>() { { Size.small, 56 }, { Size.medium, 104 }, { Size.large, 200 } }; } public override int TotalHours { get { return _hours[_size]; } } } public class WritingTask : Task { public WritingTask(int numberOfProducts, Size size) : base(numberOfProducts, size) { _pricePerHour = 650; _hours = new Dictionary<Size, int>() { { Size.small, 125 }, { Size.medium, 100 }, { Size.large, 60 } }; } public override int TotalHours { get { if (_size == Size.small) return _hours[_size] * _numberOfProducts; if (_size == Size.medium) return (_hours[Size.small] * 2) + (_hours[Size.medium] * (_numberOfProducts - 2)); return (_hours[Size.small] * 2) + (_hours[Size.medium] * (8 - 2)) + (_hours[Size.large] * (_numberOfProducts - 8)); } } } public enum Size { small, medium, large } public partial class Form1 : Form { public Form1() { InitializeComponent(); List<int> quantities = new List<int>(); for (int i = 0; i < 100; i++) { quantities.Add(i); } comboBoxNumberOfProducts.DataSource = quantities; } private void comboBoxNumberOfProducts_SelectedIndexChanged(object sender, EventArgs e) { Project project = new Project((int)comboBoxNumberOfProducts.SelectedItem); labelPrice.Text = project.GetPrice().ToString(); labelWriterHours.Text = project.Writing.TotalHours.ToString(); labelAnalysisHours.Text = project.Analysis.TotalHours.ToString(); } } At the end is a simple current calling code in the change event for a combobox that set size... (BTW, I don't like the fact that I have to use several dots to get to the TotalHours at the end here either, as far as I can recall, that violates the "principle of least knowledge" or "the law of demeter", so input on that would be appreciated too, but it's not the main point of the question) Regards, Anders

    Read the article

  • Problem with jQuery and ASP.Net MVC 2

    - by robert_d
    I have a problem with jQuery, here is how my web app works Search.aspx web page which contains a form and jQuery script posts data to Search() action in Home controller after user clicks button1 button. Search.aspx: <%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<GLSChecker.Models.WebGLSQuery>" %> <asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server"> Title </asp:Content> <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"> <h2>Search</h2> <% Html.EnableClientValidation(); %> <% using (Html.BeginForm()) {%> <fieldset> <div class="editor-label"> <%: Html.LabelFor(model => model.Url) %> </div> <div class="editor-field"> <%: Html.TextBoxFor(model => model.Url, new { size = "50" } ) %> <%: Html.ValidationMessageFor(model => model.Url) %> </div> <div class="editor-label"> <%: Html.LabelFor(model => model.Location) %> </div> <div class="editor-field"> <%: Html.TextBoxFor(model => model.Location, new { size = "50" } ) %> <%: Html.ValidationMessageFor(model => model.Location) %> </div> <div class="editor-label"> <%: Html.LabelFor(model => model.KeywordLines) %> </div> <div class="editor-field"> <%: Html.TextAreaFor(model => model.KeywordLines, 10, 60, null)%> <%: Html.ValidationMessageFor(model => model.KeywordLines)%> </div> <p> <input id ="button1" type="submit" value="Search" /> </p> </fieldset> <% } %> <script src="../../Scripts/jquery-1.4.1.js" type="text/javascript"></script> <script type="text/javascript"> jQuery("#button1").click(function (e) { window.setInterval(refreshResult, 5000); }); function refreshResult() { jQuery("#divResult").load("/Home/Refresh"); } </script> <div id="divResult"> </div> </asp:Content> [HttpPost] public ActionResult Search(WebGLSQuery queryToCreate) { if (!ModelState.IsValid) return View("Search"); queryToCreate.Remote_Address = HttpContext.Request.ServerVariables["REMOTE_ADDR"]; Session["Result"] = null; SearchKeywordLines(queryToCreate); Thread.Sleep(15000); return View("Search"); }//Search() After button1 button is clicked the above script from Search.aspx web page runs. Search() action in controller runs for longer period of time. I simulate this in testing by putting Thread.Sleep(15000); in Search()action. 5 sec. after Submit button was pressed, the above jQuery script calls Refresh() action in Home controller. public ActionResult Refresh() { ViewData["Result"] = DateTime.Now; return PartialView(); } Refresh() renders this partial <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl" % <%= ViewData["Result"] % The problem is that in Internet Explorer 8 there is only one request to /Home/Refresh; in Firefox 3.6.3 all requests to /Home/Refresh are made but nothing is displayed on the web page. Another problem with Firefox is that requests to /Home/Refresh are made every second not every 5 seconds. I noticed that after I clear Firefox cache the script works well first time button1 is pressed, but after that it doesn't work. I would be grateful for helpful suggestions.

    Read the article

  • Rails validation count limit on has_many :through

    - by Jeremy
    I've got the following models: Team, Member, Assignment, Role The Team model has_many Members. Each Member has_many roles through assignments. Role assignments are Captain and Runner. I have also installed devise and CanCan using the Member model. What I need to do is limit each Team to have a max of 1 captain and 5 runners. I found this example, and it seemed to work after some customization, but on update ('teams/1/members/4/edit'). It doesn't work on create ('teams/1/members/new'). But my other validation (validates :role_ids, :presence = true ) does work on both update and create. Any help would be appreciated. Update: I've found this example that would seem to be similar to my problem but I can't seem to make it work for my app. It seems that the root of the problem lies with how the count (or size) is performed before and during validation. For Example: When updating a record... It checks to see how many runners there are on a team and returns a count. (i.e. 5) Then when I select a role(s) to add to the member it takes the known count from the database (i.e. 5) and adds the proposed changes (i.e. 1), and then runs the validation check. (Team.find(self.team_id).members.runner.count 5) This works fine because it returns a value of 6 and 6 5 so the proposed update fails without saving and an error is given. But when I try to create a new member on the team... It checks to see how many runners there are on a team and returns a count. (i.e. 5) Then when I select a role(s) to add to the member it takes the known count from the database (i.e. 5) and then runs the validation check WITHOUT factoring in the proposed changes. This doesn't work because it returns a value of 5 known runner and 5 = 5 so the proposed update passes and the new member and role is saved to the database with no error. Member Model: class Member < ActiveRecord::Base devise :database_authenticatable, :registerable, :recoverable, :rememberable, :trackable, :validatable attr_accessible :password, :password_confirmation, :remember_me attr_accessible :age, :email, :first_name, :last_name, :sex, :shirt_size, :team_id, :assignments_attributes, :role_ids belongs_to :team has_many :assignments, :dependent => :destroy has_many :roles, through: :assignments accepts_nested_attributes_for :assignments scope :runner, joins(:roles).where('roles.title = ?', "Runner") scope :captain, joins(:roles).where('roles.title = ?', "Captain") validate :validate_runner_count validate :validate_captain_count validates :role_ids, :presence => true def validate_runner_count if Team.find(self.team_id).members.runner.count > 5 errors.add(:role_id, 'Error - Max runner limit reached') end end def validate_captain_count if Team.find(self.team_id).members.captain.count > 1 errors.add(:role_id, 'Error - Max captain limit reached') end end def has_role?(role_sym) roles.any? { |r| r.title.underscore.to_sym == role_sym } end end Member Controller: class MembersController < ApplicationController load_and_authorize_resource :team load_and_authorize_resource :member, :through => :team before_filter :get_team before_filter :initialize_check_boxes, :only => [:create, :update] def get_team @team = Team.find(params[:team_id]) end def index respond_to do |format| format.html # index.html.erb format.json { render json: @members } end end def show respond_to do |format| format.html # show.html.erb format.json { render json: @member } end end def new respond_to do |format| format.html # new.html.erb format.json { render json: @member } end end def edit end def create respond_to do |format| if @member.save format.html { redirect_to [@team, @member], notice: 'Member was successfully created.' } format.json { render json: [@team, @member], status: :created, location: [@team, @member] } else format.html { render action: "new" } format.json { render json: @member.errors, status: :unprocessable_entity } end end end def update respond_to do |format| if @member.update_attributes(params[:member]) format.html { redirect_to [@team, @member], notice: 'Member was successfully updated.' } format.json { head :no_content } else format.html { render action: "edit" } format.json { render json: @member.errors, status: :unprocessable_entity } end end end def destroy @member.destroy respond_to do |format| format.html { redirect_to team_members_url } format.json { head :no_content } end end # Allow empty checkboxes # http://railscasts.com/episodes/17-habtm-checkboxes def initialize_check_boxes params[:member][:role_ids] ||= [] end end _Form Partial <%= form_for [@team, @member], :html => { :class => 'form-horizontal' } do |f| %> #... # testing the count... <ul> <li>Captain - <%= Team.find(@member.team_id).members.captain.size %></li> <li>Runner - <%= Team.find(@member.team_id).members.runner.size %></li> <li>Driver - <%= Team.find(@member.team_id).members.driver.size %></li> </ul> <div class="control-group"> <div class="controls"> <%= f.fields_for :roles do %> <%= hidden_field_tag "member[role_ids][]", nil %> <% Role.all.each do |role| %> <%= check_box_tag "member[role_ids][]", role.id, @member.role_ids.include?(role.id), id: dom_id(role) %> <%= label_tag dom_id(role), role.title %> <% end %> <% end %> </div> </div> #... <% end %>

    Read the article

  • Search function fails because it refers to the wrong controller action?

    - by Christoffer
    My Sunspot search function (sunspot_rails gem) works just fine in my index view, but when I duplicate it to my show view my search breaks... views/supplierproducts/show.html.erb <%= form_tag supplierproducts_path, :method => :get, :id => "supplierproducts_search" do %> <p> <%= text_field_tag :search, params[:search], placeholder: "Search by SKU, product name & EAN number..." %> </p> <div id="supplierproducts"><%= render 'supplierproducts' %></div> <% end %> assets/javascripts/application.js $(function () { $('#supplierproducts th a').live('click', function () { $.getScript(this.href); return false; } ); $('#supplierproducts_search input').keyup(function () { $.get($("#supplierproducts_search").attr("action"), $("#supplierproducts_search").serialize(), null, 'script'); return false; }); }); views/supplierproducts/show.js.erb $('#supplierproducts').html('<%= escape_javascript(render("supplierproducts")) %>'); views/supplierproducts/_supplierproducts.hmtl.erb <%= hidden_field_tag :direction, params[:direction] %> <%= hidden_field_tag :sort, params[:sort] %> <table class="table table-bordered"> <thead> <tr> <th><%= sortable "sku", "SKU" %></th> <th><%= sortable "name", "Product name" %></th> <th><%= sortable "stock", "Stock" %></th> <th><%= sortable "price", "Price" %></th> <th><%= sortable "ean", "EAN number" %></th> </tr> </thead> <% for supplierproduct in @supplier.supplierproducts %> <tbody> <tr> <td><%= supplierproduct.sku %></td> <td><%= supplierproduct.name %></td> <td><%= supplierproduct.stock %></td> <td><%= supplierproduct.price %></td> <td><%= supplierproduct.ean %></td> </tr> </tbody> <% end %> </table> controllers/supplierproducts_controller.rb class SupplierproductsController < ApplicationController helper_method :sort_column, :sort_direction def show @supplier = Supplier.find(params[:id]) @search = @supplier.supplierproducts.search do fulltext params[:search] end @supplierproducts = @search.results end end private def sort_column Supplierproduct.column_names.include?(params[:sort]) ? params[:sort] : "name" end def sort_direction %w[asc desc].include?(params[:direction]) ? params[:direction] : "asc" end models/supplierproduct.rb class Supplierproduct < ActiveRecord::Base attr_accessible :ean, :name, :price, :sku, :stock, :supplier_id belongs_to :supplier validates :supplier_id, presence: true searchable do text :ean, :name, :sku end end Visiting show.html.erb works just fine. Log shows: Started GET "/supplierproducts/2" for 127.0.0.1 at 2012-06-24 13:44:52 +0200 Processing by SupplierproductsController#show as HTML Parameters: {"id"=>"2"} Supplier Load (0.1ms) SELECT "suppliers".* FROM "suppliers" WHERE "suppliers"."id" = ? LIMIT 1 [["id", "2"]] SOLR Request (252.9ms) [ path=#<RSolr::Client:0x007fa5880b8e68> parameters={data: fq=type%3ASupplierproduct&start=0&rows=30&q=%2A%3A%2A, method: post, params: {:wt=>:ruby}, query: wt=ruby, headers: {"Content-Type"=>"application/x-www-form-urlencoded; charset=UTF-8"}, path: select, uri: http://localhost:8982/solr/select?wt=ruby, open_timeout: , read_timeout: } ] Supplierproduct Load (0.2ms) SELECT "supplierproducts".* FROM "supplierproducts" WHERE "supplierproducts"."id" IN (1) Supplierproduct Load (0.1ms) SELECT "supplierproducts".* FROM "supplierproducts" WHERE "supplierproducts"."supplier_id" = 2 Rendered supplierproducts/_supplierproducts.html.erb (2.2ms) Rendered supplierproducts/show.html.erb within layouts/application (3.3ms) Rendered layouts/_shim.html.erb (0.0ms) User Load (0.1ms) SELECT "users".* FROM "users" WHERE "users"."remember_token" = 'zMrtTbDun2MjMHRApSthCQ' LIMIT 1 Rendered layouts/_header.html.erb (2.1ms) Rendered layouts/_footer.html.erb (0.2ms) Completed 200 OK in 278ms (Views: 20.6ms | ActiveRecord: 0.6ms | Solr: 252.9ms) But it breaks when I type in a search. Log shows: Started GET "/supplierproducts?utf8=%E2%9C%93&search=a&direction=&sort=&_=1340538830635" for 127.0.0.1 at 2012-06-24 13:53:50 +0200 Processing by SupplierproductsController#index as JS Parameters: {"utf8"=>"?", "search"=>"a", "direction"=>"", "sort"=>"", "_"=>"1340538830635"} Rendered supplierproducts/_supplierproducts.html.erb (2.4ms) Rendered supplierproducts/index.js.erb (2.9ms) Completed 500 Internal Server Error in 6ms ActionView::Template::Error (undefined method `supplierproducts' for nil:NilClass): 10: <th><%= sortable "ean", "EAN number" %></th> 11: </tr> 12: </thead> 13: <% for supplierproduct in @supplier.supplierproducts %> 14: <tbody> 15: <tr> 16: <td><%= supplierproduct.sku %></td> app/views/supplierproducts/_supplierproducts.html.erb:13:in `_app_views_supplierproducts__supplierproducts_html_erb___2251600857885474606_70174444831200' app/views/supplierproducts/index.js.erb:1:in `_app_views_supplierproducts_index_js_erb___1613906916161905600_70174464073480' Rendered /Users/Computer/.rvm/gems/ruby-1.9.3-p194@myapp/gems/actionpack-3.2.3/lib/action_dispatch/middleware/templates/rescues/_trace.erb (33.3ms) Rendered /Users/Computer/.rvm/gems/ruby-1.9.3-p194@myapp/gems/actionpack-3.2.3/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb (0.9ms) Rendered /Users/Computer/.rvm/gems/ruby-1.9.3-p194@myapp/gems/actionpack-3.2.3/lib/action_dispatch/middleware/templates/rescues/template_error.erb within rescues/layout (39.7ms)

    Read the article

  • passing multiple queries to view with codeigniter

    - by LvS
    I am trying to build a forum with Codeigniter. So far i have the forums themselves displayed and the threads displayed, based on the creating dynamic news tutorial. But that is 2 different pages, i need to obviously display them into one page, like this: Forum 1 - thread 1 - thread 2 - thread 3 Forum 2 - thread 1 - thread 2 etc. And then the next step is obviously to display all the posts in a thread. Most likely with some pagination going on. But that is for later. For now i have the forum controller (slimmed version): <?php class Forum extends CI_Controller { public function __construct() { parent::__construct(); $this->load->model('forum_model'); $this->lang->load('forum'); $this->lang->load('dutch'); } public function index() { $data['forums'] = $this->forum_model->get_forums(); $data['title'] = $this->lang->line('title'); $data['view'] = $this->lang->line('view'); $this->load->view('templates/header', $data); $this->load->view('forum/index', $data); $this->load->view('templates/footer'); } public function view($slug) { $data['forum_item'] = $this->forum_model->get_forums($slug); if (empty($data['forum_item'])) { show_404(); } $data['title'] = $data['forum_item']['title']; $this->load->view('templates/header', $data); $this->load->view('forum/view', $data); $this->load->view('templates/footer'); } } ?> And the forum_model (also slimmed down) <?php class Forum_model extends CI_Model { public function __construct() { $this->load->database(); } public function get_forums($slug = FALSE) { if ($slug === FALSE) { $query= $this->db->get('forum'); return $query->result_array(); } $query = $this->db->get_where('forum', array('slug' => $slug)); return $query->row_array(); } public function get_threads($forumid, $limit, $offset) { $query = $this->db->get_where('thread', array('forumid', $forumid), $limit, $offset); return $query->result_array(); } } ?> And the view file <?php foreach ($forums as $forum_item): ?> <h2><?=$forum_item['title']?></h2> <div id="main"> <?=$forum_item['description']?> </div> <p><a href="forum/<?php echo $forum_item['slug'] ?>"><?=$view?></a></p> <?php endforeach ?> Now that last one, i would like to have something like this: <?php foreach ($forums as $forum_item): ?> <h2><?=$forum_item['title']?></h2> <div id="main"> <?=$forum_item['description']?> </div> <?php foreach ($threads as $thread_item): ?> <h2><?php echo $thread_item['title'] ?></h2> <p><a href="thread/<?php echo $thread_item['slug'] ?>"><?=$view?></a></p> <?php endforeach ?> <?php endforeach ?> But the question is, how do i get the model to return like a double query to the view, so that it contains both the forums and the threads within each forum. I tried to make a foreach loop in the get_forum function, but when i do this: public function get_forums($slug = FALSE) { if ($slug === FALSE) { $query= $this->db->get('forum'); foreach ($query->row_array() as $forum_item) { $thread_query=$this->get_threads($forum_item->forumid, 50, 0); } return $query->result_array(); } $query = $this->db->get_where('forum', array('slug' => $slug)); return $query->row_array(); } i get the error A PHP Error was encountered Severity: Notice Message: Trying to get property of non-object Filename: models/forum_model.php Line Number: 16 I hope anyone has some good tips, thanks! Lenny *EDIT*** Thanks for the feedback. I have been puzzling and this seems to work now :) $query= $this->db->get('forum'); foreach ($query->result() as $forum_item) { $forum[$forum_item->forumid]['title']=$forum_item->title; $thread_query=$this->db->get_where('thread', array('forumid' => $forum_item->forumid), 20, 0); foreach ($thread_query->result() as $thread_item) { $forum[$forum_item->forumid]['thread'][]=$thread_item->title; } } return $forum; } What is now next, is how to display this multidimensional array in the view, with foreach statements.... Any suggestions ? Thanks

    Read the article

  • Google App Engine - SiteMap Creation for a social network

    - by spidee
    Hi all. I am creating a social tool - I want to allow search engines to pick up "public" user profiles - like twitter and face-book. I have seen all the protocol info at http://www.sitemaps.org and i understand this and how to build such a file - along with an index if i exceed the 50K limit. Where i am struggling is the concept of how i make this run. The site map for my general site pages is simple i can use a tool to create the file - or a script - host the file - submit the file and done. What i then need is a script that will create the site-maps of user profiles. I assume this would be something like: <?xml version="1.0" encoding="UTF-8"?> <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"> <url> <loc>http://www.socialsite.com/profile/spidee</loc> <lastmod>2010-5-12</lastmod> <changefreq>???</changefreq> <priority>???</priority> </url> <url> <loc>http://www.socialsite.com/profile/webbsterisback</loc> <lastmod>2010-5-12</lastmod> <changefreq>???</changefreq> <priority>???</priority> </url> </urlset> Ive added some ??? as i don't know how i should set these settings for my profiles based on the following:- When a new profile is created it must be added to a site-map. If the profile is changed or if "certain" properties are changed - then i don't know if i update the entry in the map - or do something else? (updating would be a nightmare!) Some users may change their profile. In terms of relevance to the search engine the only way a google or yahoo search will find the users (for my requirement) profile would be for example by means of [user name] and [location] so once the entry for the profile has been added to the map file the only reason to have the search-bot re-index the profile would be if the user changed their user-name - which they cant. or their location - and or set their settings so that their profile would be "hidden" from search engines. I assume my map creation will need to be dynamic. From what i have said above i would imagine that creating a new profile and possible editing certain properties could mark it as needing adding/updating in the sitemap. Assuming i will have millions of profiles added/being edited how can i manage this in a sensible manner. i know i need a script that can append urls as each profile is created i know the script will prob be a TASK - running at a set freq - perhaps the profiles have a property like "indexed" and the TASK sets them to "true" when the profiles are added to the map. I dont see the best way to store the map - do i store it in the datastore i.e; model=sitemaps properties key_name=sitemap_xml_1 (and for my map sitemap_index_xml) mapxml=blobstore (the raw xml map or ror map) full=boolean (set true when url count is 50) # might need this as a shard will tell us To make this work my thoughts are m cache the current site map structure as "sitemap_xml" keep a shard of url count when my task executes 1. build the xml structure for say the first 100 urls marked "index==false" (how many could u run at a time?) 2. test if the current mcache sitemap is full (shardcounter+10050K) 3.a if the map is near full create a new map entry in models "sitemap_xml_2" - update the map_index file (also stored in my model as "sitemap_index" start a new shard - or reset.2 3.b if the map is not full grab it from mcache 4.append the 100 url xml structure 5.save / m cache the map I can now add a handler using a url map/route like /sitemaps/* Get my * as map name and serve the maps from the blobstore/mache on the fly. Now my question is does this work - is this the right way or a good way to start? Will this handle the situation of making sure the search bots update when a user changes their profile - possibly by setting the change freq correctly? - Do i need a more advance system :( ? or have i re-invented the wheel! I hope this is all clear and make some form of sense :-)

    Read the article

  • Error when saving document of custom type in Alfresco Share

    - by ht0ma
    I got this exception when trying to save a new document of custom type: org.alfresco.service.cmr.repository.MalformedNodeRefException: 06010026 Invalid node ref - does not contain forward slash: {node.nodeRef} Here is how the definition of the custom type looks like: <?xml version="1.0" encoding="UTF-8"?> <!-- Definition of new Model --> <model name="ht:channelmodel" xmlns="http://www.alfresco.org/model/dictionary/1.0"> <!-- Imports are required to allow references to definitions in other models --> <imports> <!-- Import Alfresco Dictionary Definitions --> <import uri="http://www.alfresco.org/model/dictionary/1.0" prefix="d" /> <!-- Import Alfresco Content Domain Model Definitions --> <import uri="http://www.alfresco.org/model/content/1.0" prefix="cm" /> </imports> <!-- Introduction of new namespaces defined by this model --> <namespaces> <namespace uri="http://www.someco.com/model/content/1.0" prefix="ht" /> </namespaces> <types> <!-- Here comes my type --> <type name="ht:doc"> <title>Custom Document</title> <parent>cm:content</parent> <mandatory-aspects> <aspect>cm:generalclassifiable</aspect> </mandatory-aspects> </type> </types> <aspects> <aspect name="ht:channel"> <title>Content Channel</title> <properties> <property name="ht:isWeb"> <type>d:boolean</type> </property> </properties> </aspect> </aspects> </model> and here is how I set the forms for displaying the creation of a new document of my custom type (inside share-config-custom.xml) <alfresco-config> <config evaluator="string-compare" condition="DocumentLibrary"> <create-content> <content id="plain-text" mimetype="text/plain" label="Prompt" itemid="ht:doc" /> </create-content> <aspects> <visible> <aspect name="ht:channel" /> </visible> <addable> </addable> <removeable> </removeable> </aspects> <types> <type name="cm:content"> <subtype name="ht:doc" /> </type> </types> </config> <config evaluator="model-type" condition="ht:doc"> <forms> <form> <field-visibility> <show id="cm:title" force="true" /> <show id="ht:isWeb" force="true" /> </field-visibility> <appearance> <field id="cm:title"> <control template="/org/alfresco/components/form/controls/textfield.ftl" /> </field> </appearance> </form> </forms> </config> </alfresco-config> Is is something wrong with the formatting or am I missing some fields in the type definition? Thanks

    Read the article

  • How can I Include Multiples Tables in my linq to entities eager loading using mvc4 C#

    - by EBENEZER CURVELLO
    I have 6 classes and I try to use linq to Entities to get the SiglaUF information of the last deeper table (in the view - MVC). The problem is I receive the following error: "The ObjectContext instance has been disposed and can no longer be used for operations that require a connection." The view is like that: > @model IEnumerable<DiskPizzaDelivery.Models.EnderecoCliente> > @foreach (var item in Model) { > @Html.DisplayFor(modelItem => item.CEP.Cidade.UF.SiglaUF) > } The query that i use: var cliente = context.Clientes .Include(e => e.Enderecos) .Include(e1 => e1.Enderecos.Select(cep => cep.CEP)) .SingleOrDefault(); The question is: How Can I improve this query to pre loading (eager loading) "Cidade" and "UF"? See below the classes: public partial class Cliente { [Key] [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)] public int IdCliente { get; set; } public string Email { get; set; } public string Senha { get; set; } public virtual ICollection<EnderecoCliente> Enderecos { get; set; } } public partial class EnderecoCliente { public int IdEndereco { get; set; } public int IdCliente { get; set; } public string CEPEndereco { get; set; } public string Numero { get; set; } public string Complemento { get; set; } public string PontoReferencia { get; set; } public virtual Cliente Cliente { get; set; } public virtual CEP CEP { get; set; } } public partial class CEP { public string CodCep { get; set; } public string Tipo_Logradouro { get; set; } public string Logradouro { get; set; } public string Bairro { get; set; } public int CodigoUF { get; set; } public int CodigoCidade { get; set; } public virtual Cidade Cidade { get; set; } } public partial class Cidade { public int CodigoCidade { get; set; } public string NomeCidade { get; set; } public int CodigoUF { get; set; } public virtual ICollection<CEP> CEPs { get; set; } public virtual UF UF { get; set; } public virtual ICollection<UF> UFs { get; set; } } public partial class UF { public int CodigoUF { get; set; } public string SiglaUF { get; set; } public string NomeUF { get; set; } public int CodigoCidadeCapital { get; set; } public virtual ICollection<Cidade> Cidades { get; set; } public virtual Cidade Cidade { get; set; } } var cliente = context.Clientes .Where(c => c.Email == email) .Where(c => c.Senha == senha) .Include(e => e.Enderecos) .Include(e1 => e1.Enderecos.Select(cep => cep.CEP)) .SingleOrDefault(); Thanks!

    Read the article

  • 2-Bay External HDD Enclosure in JBOD mode fails to detect both drives (Linux & Windows)

    - by mgc8888
    I recently purchased a couple of USB 3.0 External HDD Enclosures to use for storage and backup; the idea was to have one act as backup to the other, with 4 x 3TB drives in total. However, the second drive in each is not accessible in either Linux nor Windows, and I could not determine the reason. 1. Situation The two enclosures are slightly different (couldn't find them in stock at the same time) yet from many little details appear to be the same Chinese base design with a tweaked outer shell. The models are: Sharkoon 2-Bay RAID Box Fantec MR-35DU3 The drives are Seagate 3TB Barracuda ST33000651AS, firmware CC44, all identical. From reading manuals and online sources, I determined that JBOD would be the optimal setup for my needs -- addressing the two drives separately in each enclosure would be important, making it easy to swap drives and mix&match them if needed; all the other modes implied the controller doing a combination of the drives. The software used was Debian GNU/Linux - testing/wheezy - kernel 2.6.39-2 and Windows 7 Ultimate. 2. Description of the problem Now, here comes the problem: every time I connect either of the enclosures to a PC using the supplied cable (tried a different one as well), only the HDD in the top bay is readable, the one below is detected yet errors out in various ways. According to the manuals, it should not happen: in JBOD, the system should be able to "see" two separate drives upon connection. This happens with both enclosures and any combination of HDDs (i.e. if I swap them, the same thing happens), so the HDDs are good and I think so are the enclosures (two different companies making similar products that failed in an identical fashion would be very unlikely). The top HDD can be used fine every time, I actually tried a speed test from Linux and got about 150MiB/s reads, so all is working as it should; the one below refuses to work every time. So the failure is consistent. To make sure this was not some obscure Linux bug, I tried the same under Windows 7, and the system also only created one drive letter for a drive of 3TB size (so it was only seeing one instead of both). Placing an older, known good, 2TB drive in the top bay made that the one recognised, so we have the same issue under Windows as well. Log entries under Linux (tested here with a 3TB and a 2TB drive so I could differentiate them; either one works in the top enclosure, in the test setup the 3TB one is on top). You can see them being detected, the top one is ok, but for the bottom one only errors: Jul 19 23:28:15 media kernel: [260150.582436] usb 6-1: New USB device found, idVendor=1ca1, idProduct=18ae Jul 19 23:28:15 media kernel: [260150.582440] usb 6-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3 Jul 19 23:28:15 media kernel: [260150.582442] usb 6-1: Product: Usb Sata Bridge Jul 19 23:28:15 media kernel: [260150.582444] usb 6-1: Manufacturer: SYMWAVE Jul 19 23:28:15 media kernel: [260150.582446] usb 6-1: SerialNumber: 39584B304C4E3441 Jul 19 23:28:15 media kernel: [260150.870412] scsi11 : usb-storage 6-1:1.0 Jul 19 23:28:16 media kernel: [260151.882087] scsi 11:0:0:0: Direct-Access SYMWAVE ST33000651AS CC44 PQ: 0 ANSI: 4 Jul 19 23:28:16 media kernel: [260151.882242] scsi 11:0:0:1: Direct-Access SYMWAVE ST32000641AS CC12 PQ: 0 ANSI: 4 Jul 19 23:28:16 media kernel: [260151.882677] sd 11:0:0:0: Attached scsi generic sg2 type 0 Jul 19 23:28:16 media kernel: [260151.882774] sd 11:0:0:0: [sdb] Very big device. Trying to use READ CAPACITY(16). Jul 19 23:28:16 media kernel: [260151.882857] sd 11:0:0:1: Attached scsi generic sg3 type 0 Jul 19 23:28:16 media kernel: [260151.882893] sd 11:0:0:0: [sdb] 5860533168 512-byte logical blocks: (3.00 TB/2.72 TiB) Jul 19 23:28:16 media kernel: [260151.883085] xhci_hcd 0000:03:00.0: WARN: Stalled endpoint Jul 19 23:28:16 media kernel: [260151.883582] sd 11:0:0:0: [sdb] Write Protect is off Jul 19 23:28:16 media kernel: [260151.883961] sd 11:0:0:1: [sdc] 3907029168 512-byte logical blocks: (2.00 TB/1.81 TiB) Jul 19 23:28:16 media kernel: [260151.884145] xhci_hcd 0000:03:00.0: WARN: Stalled endpoint Jul 19 23:28:16 media kernel: [260151.884570] sd 11:0:0:1: [sdc] Write Protect is off Jul 19 23:28:16 media kernel: [260151.884855] sd 11:0:0:0: [sdb] Very big device. Trying to use READ CAPACITY(16). Jul 19 23:28:16 media kernel: [260151.885286] xhci_hcd 0000:03:00.0: WARN: Stalled endpoint Jul 19 23:28:16 media kernel: [260151.885807] xhci_hcd 0000:03:00.0: WARN: Stalled endpoint Jul 19 23:28:16 media kernel: [260151.909595] xhci_hcd 0000:03:00.0: WARN: Stalled endpoint Jul 19 23:28:16 media kernel: [260151.910159] sd 11:0:0:1: [sdc] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE Jul 19 23:28:16 media kernel: [260151.910163] sd 11:0:0:1: [sdc] Sense Key : Illegal Request [current] Jul 19 23:28:16 media kernel: [260151.910167] Info fld=0x0 Jul 19 23:28:16 media kernel: [260151.910169] sd 11:0:0:1: [sdc] Add. Sense: Invalid field in cdb Jul 19 23:28:16 media kernel: [260151.910172] sd 11:0:0:1: [sdc] CDB: Read(10): 28 20 00 00 00 00 00 00 08 00 Jul 19 23:28:16 media kernel: [260151.910182] quiet_error: 2 callbacks suppressed Jul 19 23:28:16 media kernel: [260151.910570] xhci_hcd 0000:03:00.0: WARN: Stalled endpoint Jul 19 23:28:16 media kernel: [260151.911153] sd 11:0:0:1: [sdc] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE Jul 19 23:28:16 media kernel: [260151.911156] sd 11:0:0:1: [sdc] Sense Key : Illegal Request [current] Jul 19 23:28:16 media kernel: [260151.911159] Info fld=0x0 Jul 19 23:28:16 media kernel: [260151.911161] sd 11:0:0:1: [sdc] Add. Sense: Invalid field in cdb Jul 19 23:28:16 media kernel: [260151.911164] sd 11:0:0:1: [sdc] CDB: Read(10): 28 20 00 00 00 00 00 00 08 00 Jul 19 23:28:16 media kernel: [260151.911385] xhci_hcd 0000:03:00.0: WARN: Stalled endpoint Jul 19 23:28:16 media kernel: [260151.911902] sd 11:0:0:1: [sdc] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE Jul 19 23:28:16 media kernel: [260151.911905] sd 11:0:0:1: [sdc] Sense Key : Illegal Request [current] Jul 19 23:28:16 media kernel: [260151.911908] Info fld=0x0 Jul 19 23:28:16 media kernel: [260151.911910] sd 11:0:0:1: [sdc] Add. Sense: Invalid field in cdb Jul 19 23:28:16 media kernel: [260151.911913] sd 11:0:0:1: [sdc] CDB: Read(10): 28 20 00 00 00 00 00 00 08 00 Jul 19 23:28:16 media kernel: [260151.912128] xhci_hcd 0000:03:00.0: WARN: Stalled endpoint Jul 19 23:28:16 media kernel: [260151.912650] sd 11:0:0:1: [sdc] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE Jul 19 23:28:16 media kernel: [260151.912653] sd 11:0:0:1: [sdc] Sense Key : Illegal Request [current] Jul 19 23:28:16 media kernel: [260151.912656] Info fld=0x0 Jul 19 23:28:16 media kernel: [260151.912657] sd 11:0:0:1: [sdc] Add. Sense: Invalid field in cdb Jul 19 23:28:16 media kernel: [260151.912660] sd 11:0:0:1: [sdc] CDB: Read(10): 28 20 00 00 00 00 00 00 08 00 Jul 19 23:28:16 media kernel: [260151.912876] xhci_hcd 0000:03:00.0: WARN: Stalled endpoint Jul 19 23:28:16 media kernel: [260151.913439] sd 11:0:0:1: [sdc] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE Jul 19 23:28:16 media kernel: [260151.913442] sd 11:0:0:1: [sdc] Sense Key : Illegal Request [current] Jul 19 23:28:16 media kernel: [260151.913445] Info fld=0x0 Jul 19 23:28:16 media kernel: [260151.913446] sd 11:0:0:1: [sdc] Add. Sense: Invalid field in cdb Jul 19 23:28:16 media kernel: [260151.913449] sd 11:0:0:1: [sdc] CDB: Read(10): 28 20 00 00 00 00 00 00 08 00 Jul 19 23:28:16 media kernel: [260151.945227] xhci_hcd 0000:03:00.0: WARN: Stalled endpoint Jul 19 23:28:16 media kernel: [260151.945863] sd 11:0:0:1: [sdc] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE Jul 19 23:28:16 media kernel: [260151.945866] sd 11:0:0:1: [sdc] Sense Key : Illegal Request [current] Jul 19 23:28:16 media kernel: [260151.945870] Info fld=0x0 Jul 19 23:28:16 media kernel: [260151.945871] sd 11:0:0:1: [sdc] Add. Sense: Invalid field in cdb Jul 19 23:28:16 media kernel: [260151.945875] sd 11:0:0:1: [sdc] CDB: Read(10): 28 20 00 00 00 00 00 00 08 00 (...) and so on for like 10 seconds until it gives up (...) 3. Question So, my question would be: what is causing this? Am I missing something, should I configure things differently, is this a known limitation? Searching online for more information did not yield any useful results... Thank you in advance for any help!

    Read the article

  • Network throughput issue (ARP-related)

    - by Joel Coel
    The small college where I work is having some very strange network issues. I'm looking for any advice or ideas here. We were fine over the summer, but the trouble began few days after students returned to campus in force for the fall term. Symptoms The main symptom is that internet access will work, but it's very slow... often to the point of timeouts. As an example, a typical result from Speedtest.net will return .4Mbps download, but allow 3 to 8 Mbps upload speed. Lesser symptoms may include severely limited performance transferring data to and from our file server, or even in some cases the inability to log in to the computer (cannot reach the domain controller). The issue crosses multiple vlans, and has effected devices on nearly every vlan we operate. The issue does not impact all machines on the network. An unaffected machine will typically see at least 11Mbps download from speedtest.net, and perhaps much more depending on larger campus traffic patterns at the time. There is one variation on the larger issue. We have one vlan where users were unable to log into nearly all of the machines at all. IT staff would log in using a local administrator account (or in some cases cached credentials), and from there a release/renew or pinging the gateway would allow the machine to work... for a while. Complicating this issue is that this vlan covers our computer labs, which use software called Deep Freeze to completely reset the hard drives after a reboot. It could just the same issue manifesting differently because of stale data on machines that have not permanently altered low-level info for weeks. We were able to solve this, however, by creating a new vlan and moving the labs over to the new vlan wholesale. Instigations Eventually we noticed that the effected machines all had recent dhcp leases. We can predict when a machine will become "slow" by watching when a dhcp lease comes up for renewal. We played with setting the lease time very short for a test vlan, but all that did was remove our ability to predict when the machine would become slow. Machines with static IPs have pretty much always worked normally. Manually releasing/renewing an address will never cause a machine to become slow. In fact, in some cases this process has fixed a machine in that state. Most of the time, though, it doesn't help. We also noticed that mobile machines like laptops are likely to become slow when they cross to new vlans. Wireless on campus is divided up into "zones", where each zone maps to a small set of buildings. Moving to a new building can place you in a zone, thereby causing you to get a new address. A machine resuming from sleep mode is also very likely to be slow. Mitigations Sometimes, but not always, clearing the arp cache on an effected machine will allow it to work normally again. As already mentioned, releasing/renewing a local machine's IP address can fix that machine, but it's not guaranteed. Pinging the default gateway can also sometimes help with a slow machine. What seems to help most to mitigate the issue is clearing the arp cache on our core layer-3 switch. This switch is used for our dhcp system as the default gateway on all vlans, and it handles inter-vlan routing. The model is a 3Com 4900SX. To try to mitigate the issue, we have the cache timeout set on the switch all the way down to the lowest possible time, but it hasn't helped. I also put together a script that runs every few minutes to automatically connect to the switch and reset the cache. Unfortunately, this does not always work, and can even cause some machines to end up in the slow state for a short time (though these seem to correct themselves after a few minutes). We currently have a scheduled job that runs every 10 minutes to force the core switch to clear it's ARP cache, but this is far from perfect or desirable. Reproduction We now have a test machine that we can force into the slow state at will. It is connected to a switch with ports set up for each of our vlans. We make the machine slow by connecting to different vlans, and after a new connection or two it will be slow. It's also worth noting in this section that this has happened before at the start of prior terms, but in the past the problem has gone away on it's own after a few days. It solved itself before we had a chance to do much diagnostic work... hence why we've allowed it to drag so long into the term this time 'round; the expectation was this would be a short-lived situation. Other Factors It's worth mentioning that we have had about half a dozen switches just outright fail over the last year. These are mainly 2003/2004-era 3Coms (mostly 4200's) that were all put in at about the same time. They should still be covered under warranty, buy HP has made getting service somewhat difficult. Mostly in power supplies that have failed, but in a couple cases we have used a power supply from a switch with a failed mainboard to bring a switch with a failed power supply back to life. We do have UPS devices on all but three of four switches now, but that was not the case when I started two and a half years ago. Severe budget constraints (we were on the Dept. of Ed's financially challenged institutions list a couple years back) have forced me to look to the likes of Netgear and TrendNet for replacements, but so far these low-end models seem to be holding their own. It's also worth mentioning that the big change on our network this summer was migrating from a single cross-campus wireless SSID to the zoned approach mentioned earlier. I don't think this is the source of the issue, as like I've said: we've seen this before. However, it's possible this is exacerbating the issue, and may be much of the reason it's been so hard to isolate. Diagnosis At first it seemed clear to us, given the timing and persistent nature of the problem, that the source of the issue was an infected (or malicious) student machine doing ARP cache poisoning. However, repeated attempts to isolate the source have failed. Those attempts include numerous wireshark packet traces, and even taking entire buildings offline for brief periods. We have not been able even to find a smoking gun bad ARP entry. My current best guess is an overloaded or failing core switch, but I'm not sure on how to test for this, and the cost of replacing it blindly is steep. Again, any ideas appreciated.

    Read the article

  • Creating a dynamic, extensible C# Expando Object

    - by Rick Strahl
    I love dynamic functionality in a strongly typed language because it offers us the best of both worlds. In C# (or any of the main .NET languages) we now have the dynamic type that provides a host of dynamic features for the static C# language. One place where I've found dynamic to be incredibly useful is in building extensible types or types that expose traditionally non-object data (like dictionaries) in easier to use and more readable syntax. I wrote about a couple of these for accessing old school ADO.NET DataRows and DataReaders more easily for example. These classes are dynamic wrappers that provide easier syntax and auto-type conversions which greatly simplifies code clutter and increases clarity in existing code. ExpandoObject in .NET 4.0 Another great use case for dynamic objects is the ability to create extensible objects - objects that start out with a set of static members and then can add additional properties and even methods dynamically. The .NET 4.0 framework actually includes an ExpandoObject class which provides a very dynamic object that allows you to add properties and methods on the fly and then access them again. For example with ExpandoObject you can do stuff like this:dynamic expand = new ExpandoObject(); expand.Name = "Rick"; expand.HelloWorld = (Func<string, string>) ((string name) => { return "Hello " + name; }); Console.WriteLine(expand.Name); Console.WriteLine(expand.HelloWorld("Dufus")); Internally ExpandoObject uses a Dictionary like structure and interface to store properties and methods and then allows you to add and access properties and methods easily. As cool as ExpandoObject is it has a few shortcomings too: It's a sealed type so you can't use it as a base class It only works off 'properties' in the internal Dictionary - you can't expose existing type data It doesn't serialize to XML or with DataContractSerializer/DataContractJsonSerializer Expando - A truly extensible Object ExpandoObject is nice if you just need a dynamic container for a dictionary like structure. However, if you want to build an extensible object that starts out with a set of strongly typed properties and then allows you to extend it, ExpandoObject does not work because it's a sealed class that can't be inherited. I started thinking about this very scenario for one of my applications I'm building for a customer. In this system we are connecting to various different user stores. Each user store has the same basic requirements for username, password, name etc. But then each store also has a number of extended properties that is available to each application. In the real world scenario the data is loaded from the database in a data reader and the known properties are assigned from the known fields in the database. All unknown fields are then 'added' to the expando object dynamically. In the past I've done this very thing with a separate property - Properties - just like I do for this class. But the property and dictionary syntax is not ideal and tedious to work with. I started thinking about how to represent these extra property structures. One way certainly would be to add a Dictionary, or an ExpandoObject to hold all those extra properties. But wouldn't it be nice if the application could actually extend an existing object that looks something like this as you can with the Expando object:public class User : Westwind.Utilities.Dynamic.Expando { public string Email { get; set; } public string Password { get; set; } public string Name { get; set; } public bool Active { get; set; } public DateTime? ExpiresOn { get; set; } } and then simply start extending the properties of this object dynamically? Using the Expando object I describe later you can now do the following:[TestMethod] public void UserExampleTest() { var user = new User(); // Set strongly typed properties user.Email = "[email protected]"; user.Password = "nonya123"; user.Name = "Rickochet"; user.Active = true; // Now add dynamic properties dynamic duser = user; duser.Entered = DateTime.Now; duser.Accesses = 1; // you can also add dynamic props via indexer user["NickName"] = "AntiSocialX"; duser["WebSite"] = "http://www.west-wind.com/weblog"; // Access strong type through dynamic ref Assert.AreEqual(user.Name,duser.Name); // Access strong type through indexer Assert.AreEqual(user.Password,user["Password"]); // access dyanmically added value through indexer Assert.AreEqual(duser.Entered,user["Entered"]); // access index added value through dynamic Assert.AreEqual(user["NickName"],duser.NickName); // loop through all properties dynamic AND strong type properties (true) foreach (var prop in user.GetProperties(true)) { object val = prop.Value; if (val == null) val = "null"; Console.WriteLine(prop.Key + ": " + val.ToString()); } } As you can see this code somewhat blurs the line between a static and dynamic type. You start with a strongly typed object that has a fixed set of properties. You can then cast the object to dynamic (as I discussed in my last post) and add additional properties to the object. You can also use an indexer to add dynamic properties to the object. To access the strongly typed properties you can use either the strongly typed instance, the indexer or the dynamic cast of the object. Personally I think it's kinda cool to have an easy way to access strongly typed properties by string which can make some data scenarios much easier. To access the 'dynamically added' properties you can use either the indexer on the strongly typed object, or property syntax on the dynamic cast. Using the dynamic type allows all three modes to work on both strongly typed and dynamic properties. Finally you can iterate over all properties, both dynamic and strongly typed if you chose. Lots of flexibility. Note also that by default the Expando object works against the (this) instance meaning it extends the current object. You can also pass in a separate instance to the constructor in which case that object will be used to iterate over to find properties rather than this. Using this approach provides some really interesting functionality when use the dynamic type. To use this we have to add an explicit constructor to the Expando subclass:public class User : Westwind.Utilities.Dynamic.Expando { public string Email { get; set; } public string Password { get; set; } public string Name { get; set; } public bool Active { get; set; } public DateTime? ExpiresOn { get; set; } public User() : base() { } // only required if you want to mix in seperate instance public User(object instance) : base(instance) { } } to allow the instance to be passed. When you do you can now do:[TestMethod] public void ExpandoMixinTest() { // have Expando work on Addresses var user = new User( new Address() ); // cast to dynamicAccessToPropertyTest dynamic duser = user; // Set strongly typed properties duser.Email = "[email protected]"; user.Password = "nonya123"; // Set properties on address object duser.Address = "32 Kaiea"; //duser.Phone = "808-123-2131"; // set dynamic properties duser.NonExistantProperty = "This works too"; // shows default value Address.Phone value Console.WriteLine(duser.Phone); } Using the dynamic cast in this case allows you to access *three* different 'objects': The strong type properties, the dynamically added properties in the dictionary and the properties of the instance passed in! Effectively this gives you a way to simulate multiple inheritance (which is scary - so be very careful with this, but you can do it). How Expando works Behind the scenes Expando is a DynamicObject subclass as I discussed in my last post. By implementing a few of DynamicObject's methods you can basically create a type that can trap 'property missing' and 'method missing' operations. When you access a non-existant property a known method is fired that our code can intercept and provide a value for. Internally Expando uses a custom dictionary implementation to hold the dynamic properties you might add to your expandable object. Let's look at code first. The code for the Expando type is straight forward and given what it provides relatively short. Here it is.using System; using System.Collections.Generic; using System.Linq; using System.Dynamic; using System.Reflection; namespace Westwind.Utilities.Dynamic { /// <summary> /// Class that provides extensible properties and methods. This /// dynamic object stores 'extra' properties in a dictionary or /// checks the actual properties of the instance. /// /// This means you can subclass this expando and retrieve either /// native properties or properties from values in the dictionary. /// /// This type allows you three ways to access its properties: /// /// Directly: any explicitly declared properties are accessible /// Dynamic: dynamic cast allows access to dictionary and native properties/methods /// Dictionary: Any of the extended properties are accessible via IDictionary interface /// </summary> [Serializable] public class Expando : DynamicObject, IDynamicMetaObjectProvider { /// <summary> /// Instance of object passed in /// </summary> object Instance; /// <summary> /// Cached type of the instance /// </summary> Type InstanceType; PropertyInfo[] InstancePropertyInfo { get { if (_InstancePropertyInfo == null && Instance != null) _InstancePropertyInfo = Instance.GetType().GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.DeclaredOnly); return _InstancePropertyInfo; } } PropertyInfo[] _InstancePropertyInfo; /// <summary> /// String Dictionary that contains the extra dynamic values /// stored on this object/instance /// </summary> /// <remarks>Using PropertyBag to support XML Serialization of the dictionary</remarks> public PropertyBag Properties = new PropertyBag(); //public Dictionary<string,object> Properties = new Dictionary<string, object>(); /// <summary> /// This constructor just works off the internal dictionary and any /// public properties of this object. /// /// Note you can subclass Expando. /// </summary> public Expando() { Initialize(this); } /// <summary> /// Allows passing in an existing instance variable to 'extend'. /// </summary> /// <remarks> /// You can pass in null here if you don't want to /// check native properties and only check the Dictionary! /// </remarks> /// <param name="instance"></param> public Expando(object instance) { Initialize(instance); } protected virtual void Initialize(object instance) { Instance = instance; if (instance != null) InstanceType = instance.GetType(); } /// <summary> /// Try to retrieve a member by name first from instance properties /// followed by the collection entries. /// </summary> /// <param name="binder"></param> /// <param name="result"></param> /// <returns></returns> public override bool TryGetMember(GetMemberBinder binder, out object result) { result = null; // first check the Properties collection for member if (Properties.Keys.Contains(binder.Name)) { result = Properties[binder.Name]; return true; } // Next check for Public properties via Reflection if (Instance != null) { try { return GetProperty(Instance, binder.Name, out result); } catch { } } // failed to retrieve a property result = null; return false; } /// <summary> /// Property setter implementation tries to retrieve value from instance /// first then into this object /// </summary> /// <param name="binder"></param> /// <param name="value"></param> /// <returns></returns> public override bool TrySetMember(SetMemberBinder binder, object value) { // first check to see if there's a native property to set if (Instance != null) { try { bool result = SetProperty(Instance, binder.Name, value); if (result) return true; } catch { } } // no match - set or add to dictionary Properties[binder.Name] = value; return true; } /// <summary> /// Dynamic invocation method. Currently allows only for Reflection based /// operation (no ability to add methods dynamically). /// </summary> /// <param name="binder"></param> /// <param name="args"></param> /// <param name="result"></param> /// <returns></returns> public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result) { if (Instance != null) { try { // check instance passed in for methods to invoke if (InvokeMethod(Instance, binder.Name, args, out result)) return true; } catch { } } result = null; return false; } /// <summary> /// Reflection Helper method to retrieve a property /// </summary> /// <param name="instance"></param> /// <param name="name"></param> /// <param name="result"></param> /// <returns></returns> protected bool GetProperty(object instance, string name, out object result) { if (instance == null) instance = this; var miArray = InstanceType.GetMember(name, BindingFlags.Public | BindingFlags.GetProperty | BindingFlags.Instance); if (miArray != null && miArray.Length > 0) { var mi = miArray[0]; if (mi.MemberType == MemberTypes.Property) { result = ((PropertyInfo)mi).GetValue(instance,null); return true; } } result = null; return false; } /// <summary> /// Reflection helper method to set a property value /// </summary> /// <param name="instance"></param> /// <param name="name"></param> /// <param name="value"></param> /// <returns></returns> protected bool SetProperty(object instance, string name, object value) { if (instance == null) instance = this; var miArray = InstanceType.GetMember(name, BindingFlags.Public | BindingFlags.SetProperty | BindingFlags.Instance); if (miArray != null && miArray.Length > 0) { var mi = miArray[0]; if (mi.MemberType == MemberTypes.Property) { ((PropertyInfo)mi).SetValue(Instance, value, null); return true; } } return false; } /// <summary> /// Reflection helper method to invoke a method /// </summary> /// <param name="instance"></param> /// <param name="name"></param> /// <param name="args"></param> /// <param name="result"></param> /// <returns></returns> protected bool InvokeMethod(object instance, string name, object[] args, out object result) { if (instance == null) instance = this; // Look at the instanceType var miArray = InstanceType.GetMember(name, BindingFlags.InvokeMethod | BindingFlags.Public | BindingFlags.Instance); if (miArray != null && miArray.Length > 0) { var mi = miArray[0] as MethodInfo; result = mi.Invoke(Instance, args); return true; } result = null; return false; } /// <summary> /// Convenience method that provides a string Indexer /// to the Properties collection AND the strongly typed /// properties of the object by name. /// /// // dynamic /// exp["Address"] = "112 nowhere lane"; /// // strong /// var name = exp["StronglyTypedProperty"] as string; /// </summary> /// <remarks> /// The getter checks the Properties dictionary first /// then looks in PropertyInfo for properties. /// The setter checks the instance properties before /// checking the Properties dictionary. /// </remarks> /// <param name="key"></param> /// /// <returns></returns> public object this[string key] { get { try { // try to get from properties collection first return Properties[key]; } catch (KeyNotFoundException ex) { // try reflection on instanceType object result = null; if (GetProperty(Instance, key, out result)) return result; // nope doesn't exist throw; } } set { if (Properties.ContainsKey(key)) { Properties[key] = value; return; } // check instance for existance of type first var miArray = InstanceType.GetMember(key, BindingFlags.Public | BindingFlags.GetProperty); if (miArray != null && miArray.Length > 0) SetProperty(Instance, key, value); else Properties[key] = value; } } /// <summary> /// Returns and the properties of /// </summary> /// <param name="includeProperties"></param> /// <returns></returns> public IEnumerable<KeyValuePair<string,object>> GetProperties(bool includeInstanceProperties = false) { if (includeInstanceProperties && Instance != null) { foreach (var prop in this.InstancePropertyInfo) yield return new KeyValuePair<string, object>(prop.Name, prop.GetValue(Instance, null)); } foreach (var key in this.Properties.Keys) yield return new KeyValuePair<string, object>(key, this.Properties[key]); } /// <summary> /// Checks whether a property exists in the Property collection /// or as a property on the instance /// </summary> /// <param name="item"></param> /// <returns></returns> public bool Contains(KeyValuePair<string, object> item, bool includeInstanceProperties = false) { bool res = Properties.ContainsKey(item.Key); if (res) return true; if (includeInstanceProperties && Instance != null) { foreach (var prop in this.InstancePropertyInfo) { if (prop.Name == item.Key) return true; } } return false; } } } Although the Expando class supports an indexer, it doesn't actually implement IDictionary or even IEnumerable. It only provides the indexer and Contains() and GetProperties() methods, that work against the Properties dictionary AND the internal instance. The reason for not implementing IDictionary is that a) it doesn't add much value since you can access the Properties dictionary directly and that b) I wanted to keep the interface to class very lean so that it can serve as an entity type if desired. Implementing these IDictionary (or even IEnumerable) causes LINQ extension methods to pop up on the type which obscures the property interface and would only confuse the purpose of the type. IDictionary and IEnumerable are also problematic for XML and JSON Serialization - the XML Serializer doesn't serialize IDictionary<string,object>, nor does the DataContractSerializer. The JavaScriptSerializer does serialize, but it treats the entire object like a dictionary and doesn't serialize the strongly typed properties of the type, only the dictionary values which is also not desirable. Hence the decision to stick with only implementing the indexer to support the user["CustomProperty"] functionality and leaving iteration functions to the publicly exposed Properties dictionary. Note that the Dictionary used here is a custom PropertyBag class I created to allow for serialization to work. One important aspect for my apps is that whatever custom properties get added they have to be accessible to AJAX clients since the particular app I'm working on is a SIngle Page Web app where most of the Web access is through JSON AJAX calls. PropertyBag can serialize to XML and one way serialize to JSON using the JavaScript serializer (not the DCS serializers though). The key components that make Expando work in this code are the Properties Dictionary and the TryGetMember() and TrySetMember() methods. The Properties collection is public so if you choose you can explicitly access the collection to get better performance or to manipulate the members in internal code (like loading up dynamic values form a database). Notice that TryGetMember() and TrySetMember() both work against the dictionary AND the internal instance to retrieve and set properties. This means that user["Name"] works against native properties of the object as does user["Name"] = "RogaDugDog". What's your Use Case? This is still an early prototype but I've plugged it into one of my customer's applications and so far it's working very well. The key features for me were the ability to easily extend the type with values coming from a database and exposing those values in a nice and easy to use manner. I'm also finding that using this type of object for ViewModels works very well to add custom properties to view models. I suspect there will be lots of uses for this - I've been using the extra dictionary approach to extensibility for years - using a dynamic type to make the syntax cleaner is just a bonus here. What can you think of to use this for? Resources Source Code and Tests (GitHub) Also integrated in Westwind.Utilities of the West Wind Web Toolkit West Wind Utilities NuGet© Rick Strahl, West Wind Technologies, 2005-2012Posted in CSharp  .NET  Dynamic Types   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

    Read the article

  • SimpleMembership, Membership Providers, Universal Providers and the new ASP.NET 4.5 Web Forms and ASP.NET MVC 4 templates

    - by Jon Galloway
    The ASP.NET MVC 4 Internet template adds some new, very useful features which are built on top of SimpleMembership. These changes add some great features, like a much simpler and extensible membership API and support for OAuth. However, the new account management features require SimpleMembership and won't work against existing ASP.NET Membership Providers. I'll start with a summary of top things you need to know, then dig into a lot more detail. Summary: SimpleMembership has been designed as a replacement for traditional the previous ASP.NET Role and Membership provider system SimpleMembership solves common problems people ran into with the Membership provider system and was designed for modern user / membership / storage needs SimpleMembership integrates with the previous membership system, but you can't use a MembershipProvider with SimpleMembership The new ASP.NET MVC 4 Internet application template AccountController requires SimpleMembership and is not compatible with previous MembershipProviders You can continue to use existing ASP.NET Role and Membership providers in ASP.NET 4.5 and ASP.NET MVC 4 - just not with the ASP.NET MVC 4 AccountController The existing ASP.NET Role and Membership provider system remains supported as is part of the ASP.NET core ASP.NET 4.5 Web Forms does not use SimpleMembership; it implements OAuth on top of ASP.NET Membership The ASP.NET Web Site Administration Tool (WSAT) is not compatible with SimpleMembership The following is the result of a few conversations with Erik Porter (PM for ASP.NET MVC) to make sure I had some the overall details straight, combined with a lot of time digging around in ILSpy and Visual Studio's assembly browsing tools. SimpleMembership: The future of membership for ASP.NET The ASP.NET Membership system was introduces with ASP.NET 2.0 back in 2005. It was designed to solve common site membership requirements at the time, which generally involved username / password based registration and profile storage in SQL Server. It was designed with a few extensibility mechanisms - notably a provider system (which allowed you override some specifics like backing storage) and the ability to store additional profile information (although the additional  profile information was packed into a single column which usually required access through the API). While it's sometimes frustrating to work with, it's held up for seven years - probably since it handles the main use case (username / password based membership in a SQL Server database) smoothly and can be adapted to most other needs (again, often frustrating, but it can work). The ASP.NET Web Pages and WebMatrix efforts allowed the team an opportunity to take a new look at a lot of things - e.g. the Razor syntax started with ASP.NET Web Pages, not ASP.NET MVC. The ASP.NET Web Pages team designed SimpleMembership to (wait for it) simplify the task of dealing with membership. As Matthew Osborn said in his post Using SimpleMembership With ASP.NET WebPages: With the introduction of ASP.NET WebPages and the WebMatrix stack our team has really be focusing on making things simpler for the developer. Based on a lot of customer feedback one of the areas that we wanted to improve was the built in security in ASP.NET. So with this release we took that time to create a new built in (and default for ASP.NET WebPages) security provider. I say provider because the new stuff is still built on the existing ASP.NET framework. So what do we call this new hotness that we have created? Well, none other than SimpleMembership. SimpleMembership is an umbrella term for both SimpleMembership and SimpleRoles. Part of simplifying membership involved fixing some common problems with ASP.NET Membership. Problems with ASP.NET Membership ASP.NET Membership was very obviously designed around a set of assumptions: Users and user information would most likely be stored in a full SQL Server database or in Active Directory User and profile information would be optimized around a set of common attributes (UserName, Password, IsApproved, CreationDate, Comment, Role membership...) and other user profile information would be accessed through a profile provider Some problems fall out of these assumptions. Requires Full SQL Server for default cases The default, and most fully featured providers ASP.NET Membership providers (SQL Membership Provider, SQL Role Provider, SQL Profile Provider) require full SQL Server. They depend on stored procedure support, and they rely on SQL Server cache dependencies, they depend on agents for clean up and maintenance. So the main SQL Server based providers don't work well on SQL Server CE, won't work out of the box on SQL Azure, etc. Note: Cory Fowler recently let me know about these Updated ASP.net scripts for use with Microsoft SQL Azure which do support membership, personalization, profile, and roles. But the fact that we need a support page with a set of separate SQL scripts underscores the underlying problem. Aha, you say! Jon's forgetting the Universal Providers, a.k.a. System.Web.Providers! Hold on a bit, we'll get to those... Custom Membership Providers have to work with a SQL-Server-centric API If you want to work with another database or other membership storage system, you need to to inherit from the provider base classes and override a bunch of methods which are tightly focused on storing a MembershipUser in a relational database. It can be done (and you can often find pretty good ones that have already been written), but it's a good amount of work and often leaves you with ugly code that has a bunch of System.NotImplementedException fun since there are a lot of methods that just don't apply. Designed around a specific view of users, roles and profiles The existing providers are focused on traditional membership - a user has a username and a password, some specific roles on the site (e.g. administrator, premium user), and may have some additional "nice to have" optional information that can be accessed via an API in your application. This doesn't fit well with some modern usage patterns: In OAuth and OpenID, the user doesn't have a password Often these kinds of scenarios map better to user claims or rights instead of monolithic user roles For many sites, profile or other non-traditional information is very important and needs to come from somewhere other than an API call that maps to a database blob What would work a lot better here is a system in which you were able to define your users, rights, and other attributes however you wanted and the membership system worked with your model - not the other way around. Requires specific schema, overflow in blob columns I've already mentioned this a few times, but it bears calling out separately - ASP.NET Membership focuses on SQL Server storage, and that storage is based on a very specific database schema. SimpleMembership as a better membership system As you might have guessed, SimpleMembership was designed to address the above problems. Works with your Schema As Matthew Osborn explains in his Using SimpleMembership With ASP.NET WebPages post, SimpleMembership is designed to integrate with your database schema: All SimpleMembership requires is that there are two columns on your users table so that we can hook up to it – an “ID” column and a “username” column. The important part here is that they can be named whatever you want. For instance username doesn't have to be an alias it could be an email column you just have to tell SimpleMembership to treat that as the “username” used to log in. Matthew's example shows using a very simple user table named Users (it could be named anything) with a UserID and Username column, then a bunch of other columns he wanted in his app. Then we point SimpleMemberhip at that table with a one-liner: WebSecurity.InitializeDatabaseFile("SecurityDemo.sdf", "Users", "UserID", "Username", true); No other tables are needed, the table can be named anything we want, and can have pretty much any schema we want as long as we've got an ID and something that we can map to a username. Broaden database support to the whole SQL Server family While SimpleMembership is not database agnostic, it works across the SQL Server family. It continues to support full SQL Server, but it also works with SQL Azure, SQL Server CE, SQL Server Express, and LocalDB. Everything's implemented as SQL calls rather than requiring stored procedures, views, agents, and change notifications. Note that SimpleMembership still requires some flavor of SQL Server - it won't work with MySQL, NoSQL databases, etc. You can take a look at the code in WebMatrix.WebData.dll using a tool like ILSpy if you'd like to see why - there places where SQL Server specific SQL statements are being executed, especially when creating and initializing tables. It seems like you might be able to work with another database if you created the tables separately, but I haven't tried it and it's not supported at this point. Note: I'm thinking it would be possible for SimpleMembership (or something compatible) to run Entity Framework so it would work with any database EF supports. That seems useful to me - thoughts? Note: SimpleMembership has the same database support - anything in the SQL Server family - that Universal Providers brings to the ASP.NET Membership system. Easy to with Entity Framework Code First The problem with with ASP.NET Membership's system for storing additional account information is that it's the gate keeper. That means you're stuck with its schema and accessing profile information through its API. SimpleMembership flips that around by allowing you to use any table as a user store. That means you're in control of the user profile information, and you can access it however you'd like - it's just data. Let's look at a practical based on the AccountModel.cs class in an ASP.NET MVC 4 Internet project. Here I'm adding a Birthday property to the UserProfile class. [Table("UserProfile")] public class UserProfile { [Key] [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)] public int UserId { get; set; } public string UserName { get; set; } public DateTime Birthday { get; set; } } Now if I want to access that information, I can just grab the account by username and read the value. var context = new UsersContext(); var username = User.Identity.Name; var user = context.UserProfiles.SingleOrDefault(u => u.UserName == username); var birthday = user.Birthday; So instead of thinking of SimpleMembership as a big membership API, think of it as something that handles membership based on your user database. In SimpleMembership, everything's keyed off a user row in a table you define rather than a bunch of entries in membership tables that were out of your control. How SimpleMembership integrates with ASP.NET Membership Okay, enough sales pitch (and hopefully background) on why things have changed. How does this affect you? Let's start with a diagram to show the relationship (note: I've simplified by removing a few classes to show the important relationships): So SimpleMembershipProvider is an implementaiton of an ExtendedMembershipProvider, which inherits from MembershipProvider and adds some other account / OAuth related things. Here's what ExtendedMembershipProvider adds to MembershipProvider: The important thing to take away here is that a SimpleMembershipProvider is a MembershipProvider, but a MembershipProvider is not a SimpleMembershipProvider. This distinction is important in practice: you cannot use an existing MembershipProvider (including the Universal Providers found in System.Web.Providers) with an API that requires a SimpleMembershipProvider, including any of the calls in WebMatrix.WebData.WebSecurity or Microsoft.Web.WebPages.OAuth.OAuthWebSecurity. However, that's as far as it goes. Membership Providers still work if you're accessing them through the standard Membership API, and all of the core stuff  - including the AuthorizeAttribute, role enforcement, etc. - will work just fine and without any change. Let's look at how that affects you in terms of the new templates. Membership in the ASP.NET MVC 4 project templates ASP.NET MVC 4 offers six Project Templates: Empty - Really empty, just the assemblies, folder structure and a tiny bit of basic configuration. Basic - Like Empty, but with a bit of UI preconfigured (css / images / bundling). Internet - This has both a Home and Account controller and associated views. The Account Controller supports registration and login via either local accounts and via OAuth / OpenID providers. Intranet - Like the Internet template, but it's preconfigured for Windows Authentication. Mobile - This is preconfigured using jQuery Mobile and is intended for mobile-only sites. Web API - This is preconfigured for a service backend built on ASP.NET Web API. Out of these templates, only one (the Internet template) uses SimpleMembership. ASP.NET MVC 4 Basic template The Basic template has configuration in place to use ASP.NET Membership with the Universal Providers. You can see that configuration in the ASP.NET MVC 4 Basic template's web.config: <profile defaultProvider="DefaultProfileProvider"> <providers> <add name="DefaultProfileProvider" type="System.Web.Providers.DefaultProfileProvider, System.Web.Providers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" connectionStringName="DefaultConnection" applicationName="/" /> </providers> </profile> <membership defaultProvider="DefaultMembershipProvider"> <providers> <add name="DefaultMembershipProvider" type="System.Web.Providers.DefaultMembershipProvider, System.Web.Providers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" connectionStringName="DefaultConnection" enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false" requiresUniqueEmail="false" maxInvalidPasswordAttempts="5" minRequiredPasswordLength="6" minRequiredNonalphanumericCharacters="0" passwordAttemptWindow="10" applicationName="/" /> </providers> </membership> <roleManager defaultProvider="DefaultRoleProvider"> <providers> <add name="DefaultRoleProvider" type="System.Web.Providers.DefaultRoleProvider, System.Web.Providers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" connectionStringName="DefaultConnection" applicationName="/" /> </providers> </roleManager> <sessionState mode="InProc" customProvider="DefaultSessionProvider"> <providers> <add name="DefaultSessionProvider" type="System.Web.Providers.DefaultSessionStateProvider, System.Web.Providers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" connectionStringName="DefaultConnection" /> </providers> </sessionState> This means that it's business as usual for the Basic template as far as ASP.NET Membership works. ASP.NET MVC 4 Internet template The Internet template has a few things set up to bootstrap SimpleMembership: \Models\AccountModels.cs defines a basic user account and includes data annotations to define keys and such \Filters\InitializeSimpleMembershipAttribute.cs creates the membership database using the above model, then calls WebSecurity.InitializeDatabaseConnection which verifies that the underlying tables are in place and marks initialization as complete (for the application's lifetime) \Controllers\AccountController.cs makes heavy use of OAuthWebSecurity (for OAuth account registration / login / management) and WebSecurity. WebSecurity provides account management services for ASP.NET MVC (and Web Pages) WebSecurity can work with any ExtendedMembershipProvider. There's one in the box (SimpleMembershipProvider) but you can write your own. Since a standard MembershipProvider is not an ExtendedMembershipProvider, WebSecurity will throw exceptions if the default membership provider is a MembershipProvider rather than an ExtendedMembershipProvider. Practical example: Create a new ASP.NET MVC 4 application using the Internet application template Install the Microsoft ASP.NET Universal Providers for LocalDB NuGet package Run the application, click on Register, add a username and password, and click submit You'll get the following execption in AccountController.cs::Register: To call this method, the "Membership.Provider" property must be an instance of "ExtendedMembershipProvider". This occurs because the ASP.NET Universal Providers packages include a web.config transform that will update your web.config to add the Universal Provider configuration I showed in the Basic template example above. When WebSecurity tries to use the configured ASP.NET Membership Provider, it checks if it can be cast to an ExtendedMembershipProvider before doing anything else. So, what do you do? Options: If you want to use the new AccountController, you'll either need to use the SimpleMembershipProvider or another valid ExtendedMembershipProvider. This is pretty straightforward. If you want to use an existing ASP.NET Membership Provider in ASP.NET MVC 4, you can't use the new AccountController. You can do a few things: Replace  the AccountController.cs and AccountModels.cs in an ASP.NET MVC 4 Internet project with one from an ASP.NET MVC 3 application (you of course won't have OAuth support). Then, if you want, you can go through and remove other things that were built around SimpleMembership - the OAuth partial view, the NuGet packages (e.g. the DotNetOpenAuthAuth package, etc.) Use an ASP.NET MVC 4 Internet application template and add in a Universal Providers NuGet package. Then copy in the AccountController and AccountModel classes. Create an ASP.NET MVC 3 project and upgrade it to ASP.NET MVC 4 using the steps shown in the ASP.NET MVC 4 release notes. None of these are particularly elegant or simple. Maybe we (or just me?) can do something to make this simpler - perhaps a NuGet package. However, this should be an edge case - hopefully the cases where you'd need to create a new ASP.NET but use legacy ASP.NET Membership Providers should be pretty rare. Please let me (or, preferably the team) know if that's an incorrect assumption. Membership in the ASP.NET 4.5 project template ASP.NET 4.5 Web Forms took a different approach which builds off ASP.NET Membership. Instead of using the WebMatrix security assemblies, Web Forms uses Microsoft.AspNet.Membership.OpenAuth assembly. I'm no expert on this, but from a bit of time in ILSpy and Visual Studio's (very pretty) dependency graphs, this uses a Membership Adapter to save OAuth data into an EF managed database while still running on top of ASP.NET Membership. Note: There may be a way to use this in ASP.NET MVC 4, although it would probably take some plumbing work to hook it up. How does this fit in with Universal Providers (System.Web.Providers)? Just to summarize: Universal Providers are intended for cases where you have an existing ASP.NET Membership Provider and you want to use it with another SQL Server database backend (other than SQL Server). It doesn't require agents to handle expired session cleanup and other background tasks, it piggybacks these tasks on other calls. Universal Providers are not really, strictly speaking, universal - at least to my way of thinking. They only work with databases in the SQL Server family. Universal Providers do not work with Simple Membership. The Universal Providers packages include some web config transforms which you would normally want when you're using them. What about the Web Site Administration Tool? Visual Studio includes tooling to launch the Web Site Administration Tool (WSAT) to configure users and roles in your application. WSAT is built to work with ASP.NET Membership, and is not compatible with Simple Membership. There are two main options there: Use the WebSecurity and OAuthWebSecurity API to manage the users and roles Create a web admin using the above APIs Since SimpleMembership runs on top of your database, you can update your users as you would any other data - via EF or even in direct database edits (in development, of course)

    Read the article

  • Announcing release of ASP.NET MVC 3, IIS Express, SQL CE 4, Web Farm Framework, Orchard, WebMatrix

    - by ScottGu
    I’m excited to announce the release today of several products: ASP.NET MVC 3 NuGet IIS Express 7.5 SQL Server Compact Edition 4 Web Deploy and Web Farm Framework 2.0 Orchard 1.0 WebMatrix 1.0 The above products are all free. They build upon the .NET 4 and VS 2010 release, and add a ton of additional value to ASP.NET (both Web Forms and MVC) and the Microsoft Web Server stack. ASP.NET MVC 3 Today we are shipping the final release of ASP.NET MVC 3.  You can download and install ASP.NET MVC 3 here.  The ASP.NET MVC 3 source code (released under an OSI-compliant open source license) can also optionally be downloaded here. ASP.NET MVC 3 is a significant update that brings with it a bunch of great features.  Some of the improvements include: Razor ASP.NET MVC 3 ships with a new view-engine option called “Razor” (in addition to continuing to support/enhance the existing .aspx view engine).  Razor minimizes the number of characters and keystrokes required when writing a view template, and enables a fast, fluid coding workflow. Unlike most template syntaxes, with Razor you do not need to interrupt your coding to explicitly denote the start and end of server blocks within your HTML. The Razor parser is smart enough to infer this from your code. This enables a compact and expressive syntax which is clean, fast and fun to type.  You can learn more about Razor from some of the blog posts I’ve done about it over the last 6 months Introducing Razor New @model keyword in Razor Layouts with Razor Server-Side Comments with Razor Razor’s @: and <text> syntax Implicit and Explicit code nuggets with Razor Layouts and Sections with Razor Today’s release supports full code intellisense support for Razor (both VB and C#) with Visual Studio 2010 and the free Visual Web Developer 2010 Express. JavaScript Improvements ASP.NET MVC 3 enables richer JavaScript scenarios and takes advantage of emerging HTML5 capabilities. The AJAX and Validation helpers in ASP.NET MVC 3 now use an Unobtrusive JavaScript based approach.  Unobtrusive JavaScript avoids injecting inline JavaScript into HTML, and enables cleaner separation of behavior using the new HTML 5 “data-“ attribute convention (which conveniently works on older browsers as well – including IE6). This keeps your HTML tight and clean, and makes it easier to optionally swap out or customize JS libraries.  ASP.NET MVC 3 now includes built-in support for posting JSON-based parameters from client-side JavaScript to action methods on the server.  This makes it easier to exchange data across the client and server, and build rich JavaScript front-ends.  We think this capability will be particularly useful going forward with scenarios involving client templates and data binding (including the jQuery plugins the ASP.NET team recently contributed to the jQuery project).  Previous releases of ASP.NET MVC included the core jQuery library.  ASP.NET MVC 3 also now ships the jQuery Validate plugin (which our validation helpers use for client-side validation scenarios).  We are also now shipping and including jQuery UI by default as well (which provides a rich set of client-side JavaScript UI widgets for you to use within projects). Improved Validation ASP.NET MVC 3 includes a bunch of validation enhancements that make it even easier to work with data. Client-side validation is now enabled by default with ASP.NET MVC 3 (using an onbtrusive javascript implementation).  Today’s release also includes built-in support for Remote Validation - which enables you to annotate a model class with a validation attribute that causes ASP.NET MVC to perform a remote validation call to a server method when validating input on the client. The validation features introduced within .NET 4’s System.ComponentModel.DataAnnotations namespace are now supported by ASP.NET MVC 3.  This includes support for the new IValidatableObject interface – which enables you to perform model-level validation, and allows you to provide validation error messages specific to the state of the overall model, or between two properties within the model.  ASP.NET MVC 3 also supports the improvements made to the ValidationAttribute class in .NET 4.  ValidationAttribute now supports a new IsValid overload that provides more information about the current validation context, such as what object is being validated.  This enables richer scenarios where you can validate the current value based on another property of the model.  We’ve shipped a built-in [Compare] validation attribute  with ASP.NET MVC 3 that uses this support and makes it easy out of the box to compare and validate two property values. You can use any data access API or technology with ASP.NET MVC.  This past year, though, we’ve worked closely with the .NET data team to ensure that the new EF Code First library works really well for ASP.NET MVC applications.  These two posts of mine cover the latest EF Code First preview and demonstrates how to use it with ASP.NET MVC 3 to enable easy editing of data (with end to end client+server validation support).  The final release of EF Code First will ship in the next few weeks. Today we are also publishing the first preview of a new MvcScaffolding project.  It enables you to easily scaffold ASP.NET MVC 3 Controllers and Views, and works great with EF Code-First (and is pluggable to support other data providers).  You can learn more about it – and install it via NuGet today - from Steve Sanderson’s MvcScaffolding blog post. Output Caching Previous releases of ASP.NET MVC supported output caching content at a URL or action-method level. With ASP.NET MVC V3 we are also enabling support for partial page output caching – which allows you to easily output cache regions or fragments of a response as opposed to the entire thing.  This ends up being super useful in a lot of scenarios, and enables you to dramatically reduce the work your application does on the server.  The new partial page output caching support in ASP.NET MVC 3 enables you to easily re-use cached sub-regions/fragments of a page across multiple URLs on a site.  It supports the ability to cache the content either on the web-server, or optionally cache it within a distributed cache server like Windows Server AppFabric or memcached. I’ll post some tutorials on my blog that show how to take advantage of ASP.NET MVC 3’s new output caching support for partial page scenarios in the future. Better Dependency Injection ASP.NET MVC 3 provides better support for applying Dependency Injection (DI) and integrating with Dependency Injection/IOC containers. With ASP.NET MVC 3 you no longer need to author custom ControllerFactory classes in order to enable DI with Controllers.  You can instead just register a Dependency Injection framework with ASP.NET MVC 3 and it will resolve dependencies not only for Controllers, but also for Views, Action Filters, Model Binders, Value Providers, Validation Providers, and Model Metadata Providers that you use within your application. This makes it much easier to cleanly integrate dependency injection within your projects. Other Goodies ASP.NET MVC 3 includes dozens of other nice improvements that help to both reduce the amount of code you write, and make the code you do write cleaner.  Here are just a few examples: Improved New Project dialog that makes it easy to start new ASP.NET MVC 3 projects from templates. Improved Add->View Scaffolding support that enables the generation of even cleaner view templates. New ViewBag property that uses .NET 4’s dynamic support to make it easy to pass late-bound data from Controllers to Views. Global Filters support that allows specifying cross-cutting filter attributes (like [HandleError]) across all Controllers within an app. New [AllowHtml] attribute that allows for more granular request validation when binding form posted data to models. Sessionless controller support that allows fine grained control over whether SessionState is enabled on a Controller. New ActionResult types like HttpNotFoundResult and RedirectPermanent for common HTTP scenarios. New Html.Raw() helper to indicate that output should not be HTML encoded. New Crypto helpers for salting and hashing passwords. And much, much more… Learn More about ASP.NET MVC 3 We will be posting lots of tutorials and samples on the http://asp.net/mvc site in the weeks ahead.  Below are two good ASP.NET MVC 3 tutorials available on the site today: Build your First ASP.NET MVC 3 Application: VB and C# Building the ASP.NET MVC 3 Music Store We’ll post additional ASP.NET MVC 3 tutorials and videos on the http://asp.net/mvc site in the future. Visit it regularly to find new tutorials as they are published. How to Upgrade Existing Projects ASP.NET MVC 3 is compatible with ASP.NET MVC 2 – which means it should be easy to update existing MVC projects to ASP.NET MVC 3.  The new features in ASP.NET MVC 3 build on top of the foundational work we’ve already done with the MVC 1 and MVC 2 releases – which means that the skills, knowledge, libraries, and books you’ve acquired are all directly applicable with the MVC 3 release.  MVC 3 adds new features and capabilities – it doesn’t obsolete existing ones. You can upgrade existing ASP.NET MVC 2 projects by following the manual upgrade steps in the release notes.  Alternatively, you can use this automated ASP.NET MVC 3 upgrade tool to easily update your  existing projects. Localized Builds Today’s ASP.NET MVC 3 release is available in English.  We will be releasing localized versions of ASP.NET MVC 3 (in 9 languages) in a few days.  I’ll blog pointers to the localized downloads once they are available. NuGet Today we are also shipping NuGet – a free, open source, package manager that makes it easy for you to find, install, and use open source libraries in your projects. It works with all .NET project types (including ASP.NET Web Forms, ASP.NET MVC, WPF, WinForms, Silverlight, and Class Libraries).  You can download and install it here. NuGet enables developers who maintain open source projects (for example, .NET projects like Moq, NHibernate, Ninject, StructureMap, NUnit, Windsor, Raven, Elmah, etc) to package up their libraries and register them with an online gallery/catalog that is searchable.  The client-side NuGet tools – which include full Visual Studio integration – make it trivial for any .NET developer who wants to use one of these libraries to easily find and install it within the project they are working on. NuGet handles dependency management between libraries (for example: library1 depends on library2). It also makes it easy to update (and optionally remove) libraries from your projects later. It supports updating web.config files (if a package needs configuration settings). It also allows packages to add PowerShell scripts to a project (for example: scaffold commands). Importantly, NuGet is transparent and clean – and does not install anything at the system level. Instead it is focused on making it easy to manage libraries you use with your projects. Our goal with NuGet is to make it as simple as possible to integrate open source libraries within .NET projects.  NuGet Gallery This week we also launched a beta version of the http://nuget.org web-site – which allows anyone to easily search and browse an online gallery of open source packages available via NuGet.  The site also now allows developers to optionally submit new packages that they wish to share with others.  You can learn more about how to create and share a package here. There are hundreds of open-source .NET projects already within the NuGet Gallery today.  We hope to have thousands there in the future. IIS Express 7.5 Today we are also shipping IIS Express 7.5.  IIS Express is a free version of IIS 7.5 that is optimized for developer scenarios.  It works for both ASP.NET Web Forms and ASP.NET MVC project types. We think IIS Express combines the ease of use of the ASP.NET Web Server (aka Cassini) currently built-into Visual Studio today with the full power of IIS.  Specifically: It’s lightweight and easy to install (less than 5Mb download and a quick install) It does not require an administrator account to run/debug applications from Visual Studio It enables a full web-server feature set – including SSL, URL Rewrite, and other IIS 7.x modules It supports and enables the same extensibility model and web.config file settings that IIS 7.x support It can be installed side-by-side with the full IIS web server as well as the ASP.NET Development Server (they do not conflict at all) It works on Windows XP and higher operating systems – giving you a full IIS 7.x developer feature-set on all Windows OS platforms IIS Express (like the ASP.NET Development Server) can be quickly launched to run a site from a directory on disk.  It does not require any registration/configuration steps. This makes it really easy to launch and run for development scenarios.  You can also optionally redistribute IIS Express with your own applications if you want a lightweight web-server.  The standard IIS Express EULA now includes redistributable rights. Visual Studio 2010 SP1 adds support for IIS Express.  Read my VS 2010 SP1 and IIS Express blog post to learn more about what it enables.  SQL Server Compact Edition 4 Today we are also shipping SQL Server Compact Edition 4 (aka SQL CE 4).  SQL CE is a free, embedded, database engine that enables easy database storage. No Database Installation Required SQL CE does not require you to run a setup or install a database server in order to use it.  You can simply copy the SQL CE binaries into the \bin directory of your ASP.NET application, and then your web application can use it as a database engine.  No setup or extra security permissions are required for it to run. You do not need to have an administrator account on the machine. Just copy your web application onto any server and it will work. This is true even of medium-trust applications running in a web hosting environment. SQL CE runs in-memory within your ASP.NET application and will start-up when you first access a SQL CE database, and will automatically shutdown when your application is unloaded.  SQL CE databases are stored as files that live within the \App_Data folder of your ASP.NET Applications. Works with Existing Data APIs SQL CE 4 works with existing .NET-based data APIs, and supports a SQL Server compatible query syntax.  This means you can use existing data APIs like ADO.NET, as well as use higher-level ORMs like Entity Framework and NHibernate with SQL CE.  This enables you to use the same data programming skills and data APIs you know today. Supports Development, Testing and Production Scenarios SQL CE can be used for development scenarios, testing scenarios, and light production usage scenarios.  With the SQL CE 4 release we’ve done the engineering work to ensure that SQL CE won’t crash or deadlock when used in a multi-threaded server scenario (like ASP.NET).  This is a big change from previous releases of SQL CE – which were designed for client-only scenarios and which explicitly blocked running in web-server environments.  Starting with SQL CE 4 you can use it in a web-server as well. There are no license restrictions with SQL CE.  It is also totally free. Tooling Support with VS 2010 SP1 Visual Studio 2010 SP1 adds support for SQL CE 4 and ASP.NET Projects.  Read my VS 2010 SP1 and SQL CE 4 blog post to learn more about what it enables.  Web Deploy and Web Farm Framework 2.0 Today we are also releasing Microsoft Web Deploy V2 and Microsoft Web Farm Framework V2.  These services provide a flexible and powerful way to deploy ASP.NET applications onto either a single server, or across a web farm of machines. You can learn more about these capabilities from my previous blog posts on them: Introducing the Microsoft Web Farm Framework Automating Deployment with Microsoft Web Deploy Visit the http://iis.net website to learn more and install them. Both are free. Orchard 1.0 Today we are also releasing Orchard v1.0.  Orchard is a free, open source, community based project.  It provides Content Management System (CMS) and Blogging System support out of the box, and makes it possible to easily create and manage web-sites without having to write code (site owners can customize a site through the browser-based editing tools built-into Orchard).  Read these tutorials to learn more about how you can setup and manage your own Orchard site. Orchard itself is built as an ASP.NET MVC 3 application using Razor view templates (and by default uses SQL CE 4 for data storage).  Developers wishing to extend an Orchard site with custom functionality can open and edit it as a Visual Studio project – and add new ASP.NET MVC Controllers/Views to it.  WebMatrix 1.0 WebMatrix is a new, free, web development tool from Microsoft that provides a suite of technologies that make it easier to enable website development.  It enables a developer to start a new site by browsing and downloading an app template from an online gallery of web applications (which includes popular apps like Umbraco, DotNetNuke, Orchard, WordPress, Drupal and Joomla).  Alternatively it also enables developers to create and code web sites from scratch. WebMatrix is task focused and helps guide developers as they work on sites.  WebMatrix includes IIS Express, SQL CE 4, and ASP.NET - providing an integrated web-server, database and programming framework combination.  It also includes built-in web publishing support which makes it easy to find and deploy sites to web hosting providers. You can learn more about WebMatrix from my Introducing WebMatrix blog post this summer.  Visit http://microsoft.com/web to download and install it today. Summary I’m really excited about today’s releases – they provide a bunch of additional value that makes web development with ASP.NET, Visual Studio and the Microsoft Web Server a lot better.  A lot of folks worked hard to share this with you today. On behalf of my whole team – we hope you enjoy them! Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

    Read the article

  • VS 2010 SP1 and SQL CE

    - by ScottGu
    Last month we released the Beta of VS 2010 Service Pack 1 (SP1).  You can learn more about the VS 2010 SP1 Beta from Jason Zander’s two blog posts about it, and from Scott Hanselman’s blog post that covers some of the new capabilities enabled with it.   You can download and install the VS 2010 SP1 Beta here. Last week I blogged about the new Visual Studio support for IIS Express that we are adding with VS 2010 SP1. In today’s post I’m going to talk about the new VS 2010 SP1 tooling support for SQL CE, and walkthrough some of the cool scenarios it enables.  SQL CE – What is it and why should you care? SQL CE is a free, embedded, database engine that enables easy database storage. No Database Installation Required SQL CE does not require you to run a setup or install a database server in order to use it.  You can simply copy the SQL CE binaries into the \bin directory of your ASP.NET application, and then your web application can use it as a database engine.  No setup or extra security permissions are required for it to run. You do not need to have an administrator account on the machine. Just copy your web application onto any server and it will work. This is true even of medium-trust applications running in a web hosting environment. SQL CE runs in-memory within your ASP.NET application and will start-up when you first access a SQL CE database, and will automatically shutdown when your application is unloaded.  SQL CE databases are stored as files that live within the \App_Data folder of your ASP.NET Applications. Works with Existing Data APIs SQL CE 4 works with existing .NET-based data APIs, and supports a SQL Server compatible query syntax.  This means you can use existing data APIs like ADO.NET, as well as use higher-level ORMs like Entity Framework and NHibernate with SQL CE.  This enables you to use the same data programming skills and data APIs you know today. Supports Development, Testing and Production Scenarios SQL CE can be used for development scenarios, testing scenarios, and light production usage scenarios.  With the SQL CE 4 release we’ve done the engineering work to ensure that SQL CE won’t crash or deadlock when used in a multi-threaded server scenario (like ASP.NET).  This is a big change from previous releases of SQL CE – which were designed for client-only scenarios and which explicitly blocked running in web-server environments.  Starting with SQL CE 4 you can use it in a web-server as well. There are no license restrictions with SQL CE.  It is also totally free. Easy Migration to SQL Server SQL CE is an embedded database – which makes it ideal for development, testing, and light-usage scenarios.  For high-volume sites and applications you’ll probably want to migrate your database to use SQL Server Express (which is free), SQL Server or SQL Azure.  These servers enable much better scalability, more development features (including features like Stored Procedures – which aren’t supported with SQL CE), as well as more advanced data management capabilities. We’ll ship migration tools that enable you to optionally take SQL CE databases and easily upgrade them to use SQL Server Express, SQL Server, or SQL Azure.  You will not need to change your code when upgrading a SQL CE database to SQL Server or SQL Azure.  Our goal is to enable you to be able to simply change the database connection string in your web.config file and have your application just work. New Tooling Support for SQL CE in VS 2010 SP1 VS 2010 SP1 includes much improved tooling support for SQL CE, and adds support for using SQL CE within ASP.NET projects for the first time.  With VS 2010 SP1 you can now: Create new SQL CE Databases Edit and Modify SQL CE Database Schema and Indexes Populate SQL CE Databases within Data Use the Entity Framework (EF) designer to create model layers against SQL CE databases Use EF Code First to define model layers in code, then create a SQL CE database from them, and optionally edit the DB with VS Deploy SQL CE databases to remote servers using Web Deploy and optionally convert them to full SQL Server databases You can take advantage of all of the above features from within both ASP.NET Web Forms and ASP.NET MVC based projects. Download You can enable SQL CE tooling support within VS 2010 by first installing VS 2010 SP1 (beta). Once SP1 is installed, you’ll also then need to install the SQL CE Tools for Visual Studio download.  This is a separate download that enables the SQL CE tooling support for VS 2010 SP1. Walkthrough of Two Scenarios In this blog post I’m going to walkthrough how you can take advantage of SQL CE and VS 2010 SP1 using both an ASP.NET Web Forms and an ASP.NET MVC based application. Specifically, we’ll walkthrough: How to create a SQL CE database using VS 2010 SP1, then use the EF4 visual designers in Visual Studio to construct a model layer from it, and then display and edit the data using an ASP.NET GridView control. How to use an EF Code First approach to define a model layer using POCO classes and then have EF Code-First “auto-create” a SQL CE database for us based on our model classes.  We’ll then look at how we can use the new VS 2010 SP1 support for SQL CE to inspect the database that was created, populate it with data, and later make schema changes to it.  We’ll do all this within the context of an ASP.NET MVC based application. You can follow the two walkthroughs below on your own machine by installing VS 2010 SP1 (beta) and then installing the SQL CE Tools for Visual Studio download (which is a separate download that enables SQL CE tooling support for VS 2010 SP1). Walkthrough 1: Create a SQL CE Database, Create EF Model Classes, Edit the Data with a GridView This first walkthrough will demonstrate how to create and define a SQL CE database within an ASP.NET Web Form application.  We’ll then build an EF model layer for it and use that model layer to enable data editing scenarios with an <asp:GridView> control. Step 1: Create a new ASP.NET Web Forms Project We’ll begin by using the File->New Project menu command within Visual Studio to create a new ASP.NET Web Forms project.  We’ll use the “ASP.NET Web Application” project template option so that it has a default UI skin implemented: Step 2: Create a SQL CE Database Right click on the “App_Data” folder within the created project and choose the “Add->New Item” menu command: This will bring up the “Add Item” dialog box.  Select the “SQL Server Compact 4.0 Local Database” item (new in VS 2010 SP1) and name the database file to create “Store.sdf”: Note that SQL CE database files have a .sdf filename extension. Place them within the /App_Data folder of your ASP.NET application to enable easy deployment. When we clicked the “Add” button above a Store.sdf file was added to our project: Step 3: Adding a “Products” Table Double-clicking the “Store.sdf” database file will open it up within the Server Explorer tab.  Since it is a new database there are no tables within it: Right click on the “Tables” icon and choose the “Create Table” menu command to create a new database table.  We’ll name the new table “Products” and add 4 columns to it.  We’ll mark the first column as a primary key (and make it an identify column so that its value will automatically increment with each new row): When we click “ok” our new Products table will be created in the SQL CE database. Step 4: Populate with Data Once our Products table is created it will show up within the Server Explorer.  We can right-click it and choose the “Show Table Data” menu command to edit its data: Let’s add a few sample rows of data to it: Step 5: Create an EF Model Layer We have a SQL CE database with some data in it – let’s now create an EF Model Layer that will provide a way for us to easily query and update data within it. Let’s right-click on our project and choose the “Add->New Item” menu command.  This will bring up the “Add New Item” dialog – select the “ADO.NET Entity Data Model” item within it and name it “Store.edmx” This will add a new Store.edmx item to our solution explorer and launch a wizard that allows us to quickly create an EF model: Select the “Generate From Database” option above and click next.  Choose to use the Store.sdf SQL CE database we just created and then click next again.  The wizard will then ask you what database objects you want to import into your model.  Let’s choose to import the “Products” table we created earlier: When we click the “Finish” button Visual Studio will open up the EF designer.  It will have a Product entity already on it that maps to the “Products” table within our SQL CE database: The VS 2010 SP1 EF designer works exactly the same with SQL CE as it does already with SQL Server and SQL Express.  The Product entity above will be persisted as a class (called “Product”) that we can programmatically work against within our ASP.NET application. Step 6: Compile the Project Before using your model layer you’ll need to build your project.  Do a Ctrl+Shift+B to compile the project, or use the Build->Build Solution menu command. Step 7: Create a Page that Uses our EF Model Layer Let’s now create a simple ASP.NET Web Form that contains a GridView control that we can use to display and edit the our Products data (via the EF Model Layer we just created). Right-click on the project and choose the Add->New Item command.  Select the “Web Form from Master Page” item template, and name the page you create “Products.aspx”.  Base the master page on the “Site.Master” template that is in the root of the project. Add an <h2>Products</h2> heading the new Page, and add an <asp:gridview> control within it: Then click the “Design” tab to switch into design-view. Select the GridView control, and then click the top-right corner to display the GridView’s “Smart Tasks” UI: Choose the “New data source…” drop down option above.  This will bring up the below dialog which allows you to pick your Data Source type: Select the “Entity” data source option – which will allow us to easily connect our GridView to the EF model layer we created earlier.  This will bring up another dialog that allows us to pick our model layer: Select the “StoreEntities” option in the dropdown – which is the EF model layer we created earlier.  Then click next – which will allow us to pick which entity within it we want to bind to: Select the “Products” entity in the above dialog – which indicates that we want to bind against the “Product” entity class we defined earlier.  Then click the “Enable automatic updates” checkbox to ensure that we can both query and update Products.  When you click “Finish” VS will wire-up an <asp:EntityDataSource> to your <asp:GridView> control: The last two steps we’ll do will be to click the “Enable Editing” checkbox on the Grid (which will cause the Grid to display an “Edit” link on each row) and (optionally) use the Auto Format dialog to pick a UI template for the Grid. Step 8: Run the Application Let’s now run our application and browse to the /Products.aspx page that contains our GridView.  When we do so we’ll see a Grid UI of the Products within our SQL CE database. Clicking the “Edit” link for any of the rows will allow us to edit their values: When we click “Update” the GridView will post back the values, persist them through our EF Model Layer, and ultimately save them within our SQL CE database. Learn More about using EF with ASP.NET Web Forms Read this tutorial series on the http://asp.net site to learn more about how to use EF with ASP.NET Web Forms.  The tutorial series uses SQL Express as the database – but the nice thing is that all of the same steps/concepts can also now also be done with SQL CE.   Walkthrough 2: Using EF Code-First with SQL CE and ASP.NET MVC 3 We used a database-first approach with the sample above – where we first created the database, and then used the EF designer to create model classes from the database.  In addition to supporting a designer-based development workflow, EF also enables a more code-centric option which we call “code first development”.  Code-First Development enables a pretty sweet development workflow.  It enables you to: Define your model objects by simply writing “plain old classes” with no base classes or visual designer required Use a “convention over configuration” approach that enables database persistence without explicitly configuring anything Optionally override the convention-based persistence and use a fluent code API to fully customize the persistence mapping Optionally auto-create a database based on the model classes you define – allowing you to start from code first I’ve done several blog posts about EF Code First in the past – I really think it is great.  The good news is that it also works very well with SQL CE. The combination of SQL CE, EF Code First, and the new VS tooling support for SQL CE, enables a pretty nice workflow.  Below is a simple example of how you can use them to build a simple ASP.NET MVC 3 application. Step 1: Create a new ASP.NET MVC 3 Project We’ll begin by using the File->New Project menu command within Visual Studio to create a new ASP.NET MVC 3 project.  We’ll use the “Internet Project” template so that it has a default UI skin implemented: Step 2: Use NuGet to Install EFCodeFirst Next we’ll use the NuGet package manager (automatically installed by ASP.NET MVC 3) to add the EFCodeFirst library to our project.  We’ll use the Package Manager command shell to do this.  Bring up the package manager console within Visual Studio by selecting the View->Other Windows->Package Manager Console menu command.  Then type: install-package EFCodeFirst within the package manager console to download the EFCodeFirst library and have it be added to our project: When we enter the above command, the EFCodeFirst library will be downloaded and added to our application: Step 3: Build Some Model Classes Using a “code first” based development workflow, we will create our model classes first (even before we have a database).  We create these model classes by writing code. For this sample, we will right click on the “Models” folder of our project and add the below three classes to our project: The “Dinner” and “RSVP” model classes above are “plain old CLR objects” (aka POCO).  They do not need to derive from any base classes or implement any interfaces, and the properties they expose are standard .NET data-types.  No data persistence attributes or data code has been added to them.   The “NerdDinners” class derives from the DbContext class (which is supplied by EFCodeFirst) and handles the retrieval/persistence of our Dinner and RSVP instances from a database. Step 4: Listing Dinners We’ve written all of the code necessary to implement our model layer for this simple project.  Let’s now expose and implement the URL: /Dinners/Upcoming within our project.  We’ll use it to list upcoming dinners that happen in the future. We’ll do this by right-clicking on our “Controllers” folder and select the “Add->Controller” menu command.  We’ll name the Controller we want to create “DinnersController”.  We’ll then implement an “Upcoming” action method within it that lists upcoming dinners using our model layer above.  We will use a LINQ query to retrieve the data and pass it to a View to render with the code below: We’ll then right-click within our Upcoming method and choose the “Add-View” menu command to create an “Upcoming” view template that displays our dinners.  We’ll use the “empty” template option within the “Add View” dialog and write the below view template using Razor: Step 4: Configure our Project to use a SQL CE Database We have finished writing all of our code – our last step will be to configure a database connection-string to use. We will point our NerdDinners model class to a SQL CE database by adding the below <connectionString> to the web.config file at the top of our project: EF Code First uses a default convention where context classes will look for a connection-string that matches the DbContext class name.  Because we created a “NerdDinners” class earlier, we’ve also named our connectionstring “NerdDinners”.  Above we are configuring our connection-string to use SQL CE as the database, and telling it that our SQL CE database file will live within the \App_Data directory of our ASP.NET project. Step 5: Running our Application Now that we’ve built our application, let’s run it! We’ll browse to the /Dinners/Upcoming URL – doing so will display an empty list of upcoming dinners: You might ask – but where did it query to get the dinners from? We didn’t explicitly create a database?!? One of the cool features that EF Code-First supports is the ability to automatically create a database (based on the schema of our model classes) when the database we point it at doesn’t exist.  Above we configured  EF Code-First to point at a SQL CE database in the \App_Data\ directory of our project.  When we ran our application, EF Code-First saw that the SQL CE database didn’t exist and automatically created it for us. Step 6: Using VS 2010 SP1 to Explore our newly created SQL CE Database Click the “Show all Files” icon within the Solution Explorer and you’ll see the “NerdDinners.sdf” SQL CE database file that was automatically created for us by EF code-first within the \App_Data\ folder: We can optionally right-click on the file and “Include in Project" to add it to our solution: We can also double-click the file (regardless of whether it is added to the project) and VS 2010 SP1 will open it as a database we can edit within the “Server Explorer” tab of the IDE. Below is the view we get when we double-click our NerdDinners.sdf SQL CE file.  We can drill in to see the schema of the Dinners and RSVPs tables in the tree explorer.  Notice how two tables - Dinners and RSVPs – were automatically created for us within our SQL CE database.  This was done by EF Code First when we accessed the NerdDinners class by running our application above: We can right-click on a Table and use the “Show Table Data” command to enter some upcoming dinners in our database: We’ll use the built-in editor that VS 2010 SP1 supports to populate our table data below: And now when we hit “refresh” on the /Dinners/Upcoming URL within our browser we’ll see some upcoming dinners show up: Step 7: Changing our Model and Database Schema Let’s now modify the schema of our model layer and database, and walkthrough one way that the new VS 2010 SP1 Tooling support for SQL CE can make this easier.  With EF Code-First you typically start making database changes by modifying the model classes.  For example, let’s add an additional string property called “UrlLink” to our “Dinner” class.  We’ll use this to point to a link for more information about the event: Now when we re-run our project, and visit the /Dinners/Upcoming URL we’ll see an error thrown: We are seeing this error because EF Code-First automatically created our database, and by default when it does this it adds a table that helps tracks whether the schema of our database is in sync with our model classes.  EF Code-First helpfully throws an error when they become out of sync – making it easier to track down issues at development time that you might otherwise only find (via obscure errors) at runtime.  Note that if you do not want this feature you can turn it off by changing the default conventions of your DbContext class (in this case our NerdDinners class) to not track the schema version. Our model classes and database schema are out of sync in the above example – so how do we fix this?  There are two approaches you can use today: Delete the database and have EF Code First automatically re-create the database based on the new model class schema (losing the data within the existing DB) Modify the schema of the existing database to make it in sync with the model classes (keeping/migrating the data within the existing DB) There are a couple of ways you can do the second approach above.  Below I’m going to show how you can take advantage of the new VS 2010 SP1 Tooling support for SQL CE to use a database schema tool to modify our database structure.  We are also going to be supporting a “migrations” feature with EF in the future that will allow you to automate/script database schema migrations programmatically. Step 8: Modify our SQL CE Database Schema using VS 2010 SP1 The new SQL CE Tooling support within VS 2010 SP1 makes it easy to modify the schema of our existing SQL CE database.  To do this we’ll right-click on our “Dinners” table and choose the “Edit Table Schema” command: This will bring up the below “Edit Table” dialog.  We can rename, change or delete any of the existing columns in our table, or click at the bottom of the column listing and type to add a new column.  Below I’ve added a new “UrlLink” column of type “nvarchar” (since our property is a string): When we click ok our database will be updated to have the new column and our schema will now match our model classes. Because we are manually modifying our database schema, there is one additional step we need to take to let EF Code-First know that the database schema is in sync with our model classes.  As i mentioned earlier, when a database is automatically created by EF Code-First it adds a “EdmMetadata” table to the database to track schema versions (and hash our model classes against them to detect mismatches between our model classes and the database schema): Since we are manually updating and maintaining our database schema, we don’t need this table – and can just delete it: This will leave us with just the two tables that correspond to our model classes: And now when we re-run our /Dinners/Upcoming URL it will display the dinners correctly: One last touch we could do would be to update our view to check for the new UrlLink property and render a <a> link to it if an event has one: And now when we refresh our /Dinners/Upcoming we will see hyperlinks for the events that have a UrlLink stored in the database: Summary SQL CE provides a free, embedded, database engine that you can use to easily enable database storage.  With SQL CE 4 you can now take advantage of it within ASP.NET projects and applications (both Web Forms and MVC). VS 2010 SP1 provides tooling support that enables you to easily create, edit and modify SQL CE databases – as well as use the standard EF designer against them.  This allows you to re-use your existing skills and data knowledge while taking advantage of an embedded database option.  This is useful both for small applications (where you don’t need the scalability of a full SQL Server), as well as for development and testing scenarios – where you want to be able to rapidly develop/test your application without having a full database instance.  SQL CE makes it easy to later migrate your data to a full SQL Server or SQL Azure instance if you want to – without having to change any code in your application.  All we would need to change in the above two scenarios is the <connectionString> value within the web.config file in order to have our code run against a full SQL Server.  This provides the flexibility to scale up your application starting from a small embedded database solution as needed. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

    Read the article

  • A Taxonomy of Numerical Methods v1

    - by JoshReuben
    Numerical Analysis – When, What, (but not how) Once you understand the Math & know C++, Numerical Methods are basically blocks of iterative & conditional math code. I found the real trick was seeing the forest for the trees – knowing which method to use for which situation. Its pretty easy to get lost in the details – so I’ve tried to organize these methods in a way that I can quickly look this up. I’ve included links to detailed explanations and to C++ code examples. I’ve tried to classify Numerical methods in the following broad categories: Solving Systems of Linear Equations Solving Non-Linear Equations Iteratively Interpolation Curve Fitting Optimization Numerical Differentiation & Integration Solving ODEs Boundary Problems Solving EigenValue problems Enjoy – I did ! Solving Systems of Linear Equations Overview Solve sets of algebraic equations with x unknowns The set is commonly in matrix form Gauss-Jordan Elimination http://en.wikipedia.org/wiki/Gauss%E2%80%93Jordan_elimination C++: http://www.codekeep.net/snippets/623f1923-e03c-4636-8c92-c9dc7aa0d3c0.aspx Produces solution of the equations & the coefficient matrix Efficient, stable 2 steps: · Forward Elimination – matrix decomposition: reduce set to triangular form (0s below the diagonal) or row echelon form. If degenerate, then there is no solution · Backward Elimination –write the original matrix as the product of ints inverse matrix & its reduced row-echelon matrix à reduce set to row canonical form & use back-substitution to find the solution to the set Elementary ops for matrix decomposition: · Row multiplication · Row switching · Add multiples of rows to other rows Use pivoting to ensure rows are ordered for achieving triangular form LU Decomposition http://en.wikipedia.org/wiki/LU_decomposition C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-lu-decomposition-for-solving.html Represent the matrix as a product of lower & upper triangular matrices A modified version of GJ Elimination Advantage – can easily apply forward & backward elimination to solve triangular matrices Techniques: · Doolittle Method – sets the L matrix diagonal to unity · Crout Method - sets the U matrix diagonal to unity Note: both the L & U matrices share the same unity diagonal & can be stored compactly in the same matrix Gauss-Seidel Iteration http://en.wikipedia.org/wiki/Gauss%E2%80%93Seidel_method C++: http://www.nr.com/forum/showthread.php?t=722 Transform the linear set of equations into a single equation & then use numerical integration (as integration formulas have Sums, it is implemented iteratively). an optimization of Gauss-Jacobi: 1.5 times faster, requires 0.25 iterations to achieve the same tolerance Solving Non-Linear Equations Iteratively find roots of polynomials – there may be 0, 1 or n solutions for an n order polynomial use iterative techniques Iterative methods · used when there are no known analytical techniques · Requires set functions to be continuous & differentiable · Requires an initial seed value – choice is critical to convergence à conduct multiple runs with different starting points & then select best result · Systematic - iterate until diminishing returns, tolerance or max iteration conditions are met · bracketing techniques will always yield convergent solutions, non-bracketing methods may fail to converge Incremental method if a nonlinear function has opposite signs at 2 ends of a small interval x1 & x2, then there is likely to be a solution in their interval – solutions are detected by evaluating a function over interval steps, for a change in sign, adjusting the step size dynamically. Limitations – can miss closely spaced solutions in large intervals, cannot detect degenerate (coinciding) solutions, limited to functions that cross the x-axis, gives false positives for singularities Fixed point method http://en.wikipedia.org/wiki/Fixed-point_iteration C++: http://books.google.co.il/books?id=weYj75E_t6MC&pg=PA79&lpg=PA79&dq=fixed+point+method++c%2B%2B&source=bl&ots=LQ-5P_taoC&sig=lENUUIYBK53tZtTwNfHLy5PEWDk&hl=en&sa=X&ei=wezDUPW1J5DptQaMsIHQCw&redir_esc=y#v=onepage&q=fixed%20point%20method%20%20c%2B%2B&f=false Algebraically rearrange a solution to isolate a variable then apply incremental method Bisection method http://en.wikipedia.org/wiki/Bisection_method C++: http://numericalcomputing.wordpress.com/category/algorithms/ Bracketed - Select an initial interval, keep bisecting it ad midpoint into sub-intervals and then apply incremental method on smaller & smaller intervals – zoom in Adv: unaffected by function gradient à reliable Disadv: slow convergence False Position Method http://en.wikipedia.org/wiki/False_position_method C++: http://www.dreamincode.net/forums/topic/126100-bisection-and-false-position-methods/ Bracketed - Select an initial interval , & use the relative value of function at interval end points to select next sub-intervals (estimate how far between the end points the solution might be & subdivide based on this) Newton-Raphson method http://en.wikipedia.org/wiki/Newton's_method C++: http://www-users.cselabs.umn.edu/classes/Summer-2012/csci1113/index.php?page=./newt3 Also known as Newton's method Convenient, efficient Not bracketed – only a single initial guess is required to start iteration – requires an analytical expression for the first derivative of the function as input. Evaluates the function & its derivative at each step. Can be extended to the Newton MutiRoot method for solving multiple roots Can be easily applied to an of n-coupled set of non-linear equations – conduct a Taylor Series expansion of a function, dropping terms of order n, rewrite as a Jacobian matrix of PDs & convert to simultaneous linear equations !!! Secant Method http://en.wikipedia.org/wiki/Secant_method C++: http://forum.vcoderz.com/showthread.php?p=205230 Unlike N-R, can estimate first derivative from an initial interval (does not require root to be bracketed) instead of inputting it Since derivative is approximated, may converge slower. Is fast in practice as it does not have to evaluate the derivative at each step. Similar implementation to False Positive method Birge-Vieta Method http://mat.iitm.ac.in/home/sryedida/public_html/caimna/transcendental/polynomial%20methods/bv%20method.html C++: http://books.google.co.il/books?id=cL1boM2uyQwC&pg=SA3-PA51&lpg=SA3-PA51&dq=Birge-Vieta+Method+c%2B%2B&source=bl&ots=QZmnDTK3rC&sig=BPNcHHbpR_DKVoZXrLi4nVXD-gg&hl=en&sa=X&ei=R-_DUK2iNIjzsgbE5ID4Dg&redir_esc=y#v=onepage&q=Birge-Vieta%20Method%20c%2B%2B&f=false combines Horner's method of polynomial evaluation (transforming into lesser degree polynomials that are more computationally efficient to process) with Newton-Raphson to provide a computational speed-up Interpolation Overview Construct new data points for as close as possible fit within range of a discrete set of known points (that were obtained via sampling, experimentation) Use Taylor Series Expansion of a function f(x) around a specific value for x Linear Interpolation http://en.wikipedia.org/wiki/Linear_interpolation C++: http://www.hamaluik.com/?p=289 Straight line between 2 points à concatenate interpolants between each pair of data points Bilinear Interpolation http://en.wikipedia.org/wiki/Bilinear_interpolation C++: http://supercomputingblog.com/graphics/coding-bilinear-interpolation/2/ Extension of the linear function for interpolating functions of 2 variables – perform linear interpolation first in 1 direction, then in another. Used in image processing – e.g. texture mapping filter. Uses 4 vertices to interpolate a value within a unit cell. Lagrange Interpolation http://en.wikipedia.org/wiki/Lagrange_polynomial C++: http://www.codecogs.com/code/maths/approximation/interpolation/lagrange.php For polynomials Requires recomputation for all terms for each distinct x value – can only be applied for small number of nodes Numerically unstable Barycentric Interpolation http://epubs.siam.org/doi/pdf/10.1137/S0036144502417715 C++: http://www.gamedev.net/topic/621445-barycentric-coordinates-c-code-check/ Rearrange the terms in the equation of the Legrange interpolation by defining weight functions that are independent of the interpolated value of x Newton Divided Difference Interpolation http://en.wikipedia.org/wiki/Newton_polynomial C++: http://jee-appy.blogspot.co.il/2011/12/newton-divided-difference-interpolation.html Hermite Divided Differences: Interpolation polynomial approximation for a given set of data points in the NR form - divided differences are used to approximately calculate the various differences. For a given set of 3 data points , fit a quadratic interpolant through the data Bracketed functions allow Newton divided differences to be calculated recursively Difference table Cubic Spline Interpolation http://en.wikipedia.org/wiki/Spline_interpolation C++: https://www.marcusbannerman.co.uk/index.php/home/latestarticles/42-articles/96-cubic-spline-class.html Spline is a piecewise polynomial Provides smoothness – for interpolations with significantly varying data Use weighted coefficients to bend the function to be smooth & its 1st & 2nd derivatives are continuous through the edge points in the interval Curve Fitting A generalization of interpolating whereby given data points may contain noise à the curve does not necessarily pass through all the points Least Squares Fit http://en.wikipedia.org/wiki/Least_squares C++: http://www.ccas.ru/mmes/educat/lab04k/02/least-squares.c Residual – difference between observed value & expected value Model function is often chosen as a linear combination of the specified functions Determines: A) The model instance in which the sum of squared residuals has the least value B) param values for which model best fits data Straight Line Fit Linear correlation between independent variable and dependent variable Linear Regression http://en.wikipedia.org/wiki/Linear_regression C++: http://www.oocities.org/david_swaim/cpp/linregc.htm Special case of statistically exact extrapolation Leverage least squares Given a basis function, the sum of the residuals is determined and the corresponding gradient equation is expressed as a set of normal linear equations in matrix form that can be solved (e.g. using LU Decomposition) Can be weighted - Drop the assumption that all errors have the same significance –-> confidence of accuracy is different for each data point. Fit the function closer to points with higher weights Polynomial Fit - use a polynomial basis function Moving Average http://en.wikipedia.org/wiki/Moving_average C++: http://www.codeproject.com/Articles/17860/A-Simple-Moving-Average-Algorithm Used for smoothing (cancel fluctuations to highlight longer-term trends & cycles), time series data analysis, signal processing filters Replace each data point with average of neighbors. Can be simple (SMA), weighted (WMA), exponential (EMA). Lags behind latest data points – extra weight can be given to more recent data points. Weights can decrease arithmetically or exponentially according to distance from point. Parameters: smoothing factor, period, weight basis Optimization Overview Given function with multiple variables, find Min (or max by minimizing –f(x)) Iterative approach Efficient, but not necessarily reliable Conditions: noisy data, constraints, non-linear models Detection via sign of first derivative - Derivative of saddle points will be 0 Local minima Bisection method Similar method for finding a root for a non-linear equation Start with an interval that contains a minimum Golden Search method http://en.wikipedia.org/wiki/Golden_section_search C++: http://www.codecogs.com/code/maths/optimization/golden.php Bisect intervals according to golden ratio 0.618.. Achieves reduction by evaluating a single function instead of 2 Newton-Raphson Method Brent method http://en.wikipedia.org/wiki/Brent's_method C++: http://people.sc.fsu.edu/~jburkardt/cpp_src/brent/brent.cpp Based on quadratic or parabolic interpolation – if the function is smooth & parabolic near to the minimum, then a parabola fitted through any 3 points should approximate the minima – fails when the 3 points are collinear , in which case the denominator is 0 Simplex Method http://en.wikipedia.org/wiki/Simplex_algorithm C++: http://www.codeguru.com/cpp/article.php/c17505/Simplex-Optimization-Algorithm-and-Implemetation-in-C-Programming.htm Find the global minima of any multi-variable function Direct search – no derivatives required At each step it maintains a non-degenerative simplex – a convex hull of n+1 vertices. Obtains the minimum for a function with n variables by evaluating the function at n-1 points, iteratively replacing the point of worst result with the point of best result, shrinking the multidimensional simplex around the best point. Point replacement involves expanding & contracting the simplex near the worst value point to determine a better replacement point Oscillation can be avoided by choosing the 2nd worst result Restart if it gets stuck Parameters: contraction & expansion factors Simulated Annealing http://en.wikipedia.org/wiki/Simulated_annealing C++: http://code.google.com/p/cppsimulatedannealing/ Analogy to heating & cooling metal to strengthen its structure Stochastic method – apply random permutation search for global minima - Avoid entrapment in local minima via hill climbing Heating schedule - Annealing schedule params: temperature, iterations at each temp, temperature delta Cooling schedule – can be linear, step-wise or exponential Differential Evolution http://en.wikipedia.org/wiki/Differential_evolution C++: http://www.amichel.com/de/doc/html/ More advanced stochastic methods analogous to biological processes: Genetic algorithms, evolution strategies Parallel direct search method against multiple discrete or continuous variables Initial population of variable vectors chosen randomly – if weighted difference vector of 2 vectors yields a lower objective function value then it replaces the comparison vector Many params: #parents, #variables, step size, crossover constant etc Convergence is slow – many more function evaluations than simulated annealing Numerical Differentiation Overview 2 approaches to finite difference methods: · A) approximate function via polynomial interpolation then differentiate · B) Taylor series approximation – additionally provides error estimate Finite Difference methods http://en.wikipedia.org/wiki/Finite_difference_method C++: http://www.wpi.edu/Pubs/ETD/Available/etd-051807-164436/unrestricted/EAMPADU.pdf Find differences between high order derivative values - Approximate differential equations by finite differences at evenly spaced data points Based on forward & backward Taylor series expansion of f(x) about x plus or minus multiples of delta h. Forward / backward difference - the sums of the series contains even derivatives and the difference of the series contains odd derivatives – coupled equations that can be solved. Provide an approximation of the derivative within a O(h^2) accuracy There is also central difference & extended central difference which has a O(h^4) accuracy Richardson Extrapolation http://en.wikipedia.org/wiki/Richardson_extrapolation C++: http://mathscoding.blogspot.co.il/2012/02/introduction-richardson-extrapolation.html A sequence acceleration method applied to finite differences Fast convergence, high accuracy O(h^4) Derivatives via Interpolation Cannot apply Finite Difference method to discrete data points at uneven intervals – so need to approximate the derivative of f(x) using the derivative of the interpolant via 3 point Lagrange Interpolation Note: the higher the order of the derivative, the lower the approximation precision Numerical Integration Estimate finite & infinite integrals of functions More accurate procedure than numerical differentiation Use when it is not possible to obtain an integral of a function analytically or when the function is not given, only the data points are Newton Cotes Methods http://en.wikipedia.org/wiki/Newton%E2%80%93Cotes_formulas C++: http://www.siafoo.net/snippet/324 For equally spaced data points Computationally easy – based on local interpolation of n rectangular strip areas that is piecewise fitted to a polynomial to get the sum total area Evaluate the integrand at n+1 evenly spaced points – approximate definite integral by Sum Weights are derived from Lagrange Basis polynomials Leverage Trapezoidal Rule for default 2nd formulas, Simpson 1/3 Rule for substituting 3 point formulas, Simpson 3/8 Rule for 4 point formulas. For 4 point formulas use Bodes Rule. Higher orders obtain more accurate results Trapezoidal Rule uses simple area, Simpsons Rule replaces the integrand f(x) with a quadratic polynomial p(x) that uses the same values as f(x) for its end points, but adds a midpoint Romberg Integration http://en.wikipedia.org/wiki/Romberg's_method C++: http://code.google.com/p/romberg-integration/downloads/detail?name=romberg.cpp&can=2&q= Combines trapezoidal rule with Richardson Extrapolation Evaluates the integrand at equally spaced points The integrand must have continuous derivatives Each R(n,m) extrapolation uses a higher order integrand polynomial replacement rule (zeroth starts with trapezoidal) à a lower triangular matrix set of equation coefficients where the bottom right term has the most accurate approximation. The process continues until the difference between 2 successive diagonal terms becomes sufficiently small. Gaussian Quadrature http://en.wikipedia.org/wiki/Gaussian_quadrature C++: http://www.alglib.net/integration/gaussianquadratures.php Data points are chosen to yield best possible accuracy – requires fewer evaluations Ability to handle singularities, functions that are difficult to evaluate The integrand can include a weighting function determined by a set of orthogonal polynomials. Points & weights are selected so that the integrand yields the exact integral if f(x) is a polynomial of degree <= 2n+1 Techniques (basically different weighting functions): · Gauss-Legendre Integration w(x)=1 · Gauss-Laguerre Integration w(x)=e^-x · Gauss-Hermite Integration w(x)=e^-x^2 · Gauss-Chebyshev Integration w(x)= 1 / Sqrt(1-x^2) Solving ODEs Use when high order differential equations cannot be solved analytically Evaluated under boundary conditions RK for systems – a high order differential equation can always be transformed into a coupled first order system of equations Euler method http://en.wikipedia.org/wiki/Euler_method C++: http://rosettacode.org/wiki/Euler_method First order Runge–Kutta method. Simple recursive method – given an initial value, calculate derivative deltas. Unstable & not very accurate (O(h) error) – not used in practice A first-order method - the local error (truncation error per step) is proportional to the square of the step size, and the global error (error at a given time) is proportional to the step size In evolving solution between data points xn & xn+1, only evaluates derivatives at beginning of interval xn à asymmetric at boundaries Higher order Runge Kutta http://en.wikipedia.org/wiki/Runge%E2%80%93Kutta_methods C++: http://www.dreamincode.net/code/snippet1441.htm 2nd & 4th order RK - Introduces parameterized midpoints for more symmetric solutions à accuracy at higher computational cost Adaptive RK – RK-Fehlberg – estimate the truncation at each integration step & automatically adjust the step size to keep error within prescribed limits. At each step 2 approximations are compared – if in disagreement to a specific accuracy, the step size is reduced Boundary Value Problems Where solution of differential equations are located at 2 different values of the independent variable x à more difficult, because cannot just start at point of initial value – there may not be enough starting conditions available at the end points to produce a unique solution An n-order equation will require n boundary conditions – need to determine the missing n-1 conditions which cause the given conditions at the other boundary to be satisfied Shooting Method http://en.wikipedia.org/wiki/Shooting_method C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-shooting-method-for-solving.html Iteratively guess the missing values for one end & integrate, then inspect the discrepancy with the boundary values of the other end to adjust the estimate Given the starting boundary values u1 & u2 which contain the root u, solve u given the false position method (solving the differential equation as an initial value problem via 4th order RK), then use u to solve the differential equations. Finite Difference Method For linear & non-linear systems Higher order derivatives require more computational steps – some combinations for boundary conditions may not work though Improve the accuracy by increasing the number of mesh points Solving EigenValue Problems An eigenvalue can substitute a matrix when doing matrix multiplication à convert matrix multiplication into a polynomial EigenValue For a given set of equations in matrix form, determine what are the solution eigenvalue & eigenvectors Similar Matrices - have same eigenvalues. Use orthogonal similarity transforms to reduce a matrix to diagonal form from which eigenvalue(s) & eigenvectors can be computed iteratively Jacobi method http://en.wikipedia.org/wiki/Jacobi_method C++: http://people.sc.fsu.edu/~jburkardt/classes/acs2_2008/openmp/jacobi/jacobi.html Robust but Computationally intense – use for small matrices < 10x10 Power Iteration http://en.wikipedia.org/wiki/Power_iteration For any given real symmetric matrix, generate the largest single eigenvalue & its eigenvectors Simplest method – does not compute matrix decomposition à suitable for large, sparse matrices Inverse Iteration Variation of power iteration method – generates the smallest eigenvalue from the inverse matrix Rayleigh Method http://en.wikipedia.org/wiki/Rayleigh's_method_of_dimensional_analysis Variation of power iteration method Rayleigh Quotient Method Variation of inverse iteration method Matrix Tri-diagonalization Method Use householder algorithm to reduce an NxN symmetric matrix to a tridiagonal real symmetric matrix vua N-2 orthogonal transforms     Whats Next Outside of Numerical Methods there are lots of different types of algorithms that I’ve learned over the decades: Data Mining – (I covered this briefly in a previous post: http://geekswithblogs.net/JoshReuben/archive/2007/12/31/ssas-dm-algorithms.aspx ) Search & Sort Routing Problem Solving Logical Theorem Proving Planning Probabilistic Reasoning Machine Learning Solvers (eg MIP) Bioinformatics (Sequence Alignment, Protein Folding) Quant Finance (I read Wilmott’s books – interesting) Sooner or later, I’ll cover the above topics as well.

    Read the article

  • C#/.NET Little Wonders: The Concurrent Collections (1 of 3)

    - by James Michael Hare
    Once again we consider some of the lesser known classes and keywords of C#.  In the next few weeks, we will discuss the concurrent collections and how they have changed the face of concurrent programming. This week’s post will begin with a general introduction and discuss the ConcurrentStack<T> and ConcurrentQueue<T>.  Then in the following post we’ll discuss the ConcurrentDictionary<T> and ConcurrentBag<T>.  Finally, we shall close on the third post with a discussion of the BlockingCollection<T>. For more of the "Little Wonders" posts, see the index here. A brief history of collections In the beginning was the .NET 1.0 Framework.  And out of this framework emerged the System.Collections namespace, and it was good.  It contained all the basic things a growing programming language needs like the ArrayList and Hashtable collections.  The main problem, of course, with these original collections is that they held items of type object which means you had to be disciplined enough to use them correctly or you could end up with runtime errors if you got an object of a type you weren't expecting. Then came .NET 2.0 and generics and our world changed forever!  With generics the C# language finally got an equivalent of the very powerful C++ templates.  As such, the System.Collections.Generic was born and we got type-safe versions of all are favorite collections.  The List<T> succeeded the ArrayList and the Dictionary<TKey,TValue> succeeded the Hashtable and so on.  The new versions of the library were not only safer because they checked types at compile-time, in many cases they were more performant as well.  So much so that it's Microsoft's recommendation that the System.Collections original collections only be used for backwards compatibility. So we as developers came to know and love the generic collections and took them into our hearts and embraced them.  The problem is, thread safety in both the original collections and the generic collections can be problematic, for very different reasons. Now, if you are only doing single-threaded development you may not care – after all, no locking is required.  Even if you do have multiple threads, if a collection is “load-once, read-many” you don’t need to do anything to protect that container from multi-threaded access, as illustrated below: 1: public static class OrderTypeTranslator 2: { 3: // because this dictionary is loaded once before it is ever accessed, we don't need to synchronize 4: // multi-threaded read access 5: private static readonly Dictionary<string, char> _translator = new Dictionary<string, char> 6: { 7: {"New", 'N'}, 8: {"Update", 'U'}, 9: {"Cancel", 'X'} 10: }; 11:  12: // the only public interface into the dictionary is for reading, so inherently thread-safe 13: public static char? Translate(string orderType) 14: { 15: char charValue; 16: if (_translator.TryGetValue(orderType, out charValue)) 17: { 18: return charValue; 19: } 20:  21: return null; 22: } 23: } Unfortunately, most of our computer science problems cannot get by with just single-threaded applications or with multi-threading in a load-once manner.  Looking at  today's trends, it's clear to see that computers are not so much getting faster because of faster processor speeds -- we've nearly reached the limits we can push through with today's technologies -- but more because we're adding more cores to the boxes.  With this new hardware paradigm, it is even more important to use multi-threaded applications to take full advantage of parallel processing to achieve higher application speeds. So let's look at how to use collections in a thread-safe manner. Using historical collections in a concurrent fashion The early .NET collections (System.Collections) had a Synchronized() static method that could be used to wrap the early collections to make them completely thread-safe.  This paradigm was dropped in the generic collections (System.Collections.Generic) because having a synchronized wrapper resulted in atomic locks for all operations, which could prove overkill in many multithreading situations.  Thus the paradigm shifted to having the user of the collection specify their own locking, usually with an external object: 1: public class OrderAggregator 2: { 3: private static readonly Dictionary<string, List<Order>> _orders = new Dictionary<string, List<Order>>(); 4: private static readonly _orderLock = new object(); 5:  6: public void Add(string accountNumber, Order newOrder) 7: { 8: List<Order> ordersForAccount; 9:  10: // a complex operation like this should all be protected 11: lock (_orderLock) 12: { 13: if (!_orders.TryGetValue(accountNumber, out ordersForAccount)) 14: { 15: _orders.Add(accountNumber, ordersForAccount = new List<Order>()); 16: } 17:  18: ordersForAccount.Add(newOrder); 19: } 20: } 21: } Notice how we’re performing several operations on the dictionary under one lock.  With the Synchronized() static methods of the early collections, you wouldn’t be able to specify this level of locking (a more macro-level).  So in the generic collections, it was decided that if a user needed synchronization, they could implement their own locking scheme instead so that they could provide synchronization as needed. The need for better concurrent access to collections Here’s the problem: it’s relatively easy to write a collection that locks itself down completely for access, but anything more complex than that can be difficult and error-prone to write, and much less to make it perform efficiently!  For example, what if you have a Dictionary that has frequent reads but in-frequent updates?  Do you want to lock down the entire Dictionary for every access?  This would be overkill and would prevent concurrent reads.  In such cases you could use something like a ReaderWriterLockSlim which allows for multiple readers in a lock, and then once a writer grabs the lock it blocks all further readers until the writer is done (in a nutshell).  This is all very complex stuff to consider. Fortunately, this is where the Concurrent Collections come in.  The Parallel Computing Platform team at Microsoft went through great pains to determine how to make a set of concurrent collections that would have the best performance characteristics for general case multi-threaded use. Now, as in all things involving threading, you should always make sure you evaluate all your container options based on the particular usage scenario and the degree of parallelism you wish to acheive. This article should not be taken to understand that these collections are always supperior to the generic collections. Each fills a particular need for a particular situation. Understanding what each container is optimized for is key to the success of your application whether it be single-threaded or multi-threaded. General points to consider with the concurrent collections The MSDN points out that the concurrent collections all support the ICollection interface. However, since the collections are already synchronized, the IsSynchronized property always returns false, and SyncRoot always returns null.  Thus you should not attempt to use these properties for synchronization purposes. Note that since the concurrent collections also may have different operations than the traditional data structures you may be used to.  Now you may ask why they did this, but it was done out of necessity to keep operations safe and atomic.  For example, in order to do a Pop() on a stack you have to know the stack is non-empty, but between the time you check the stack’s IsEmpty property and then do the Pop() another thread may have come in and made the stack empty!  This is why some of the traditional operations have been changed to make them safe for concurrent use. In addition, some properties and methods in the concurrent collections achieve concurrency by creating a snapshot of the collection, which means that some operations that were traditionally O(1) may now be O(n) in the concurrent models.  I’ll try to point these out as we talk about each collection so you can be aware of any potential performance impacts.  Finally, all the concurrent containers are safe for enumeration even while being modified, but some of the containers support this in different ways (snapshot vs. dirty iteration).  Once again I’ll highlight how thread-safe enumeration works for each collection. ConcurrentStack<T>: The thread-safe LIFO container The ConcurrentStack<T> is the thread-safe counterpart to the System.Collections.Generic.Stack<T>, which as you may remember is your standard last-in-first-out container.  If you think of algorithms that favor stack usage (for example, depth-first searches of graphs and trees) then you can see how using a thread-safe stack would be of benefit. The ConcurrentStack<T> achieves thread-safe access by using System.Threading.Interlocked operations.  This means that the multi-threaded access to the stack requires no traditional locking and is very, very fast! For the most part, the ConcurrentStack<T> behaves like it’s Stack<T> counterpart with a few differences: Pop() was removed in favor of TryPop() Returns true if an item existed and was popped and false if empty. PushRange() and TryPopRange() were added Allows you to push multiple items and pop multiple items atomically. Count takes a snapshot of the stack and then counts the items. This means it is a O(n) operation, if you just want to check for an empty stack, call IsEmpty instead which is O(1). ToArray() and GetEnumerator() both also take snapshots. This means that iteration over a stack will give you a static view at the time of the call and will not reflect updates. Pushing on a ConcurrentStack<T> works just like you’d expect except for the aforementioned PushRange() method that was added to allow you to push a range of items concurrently. 1: var stack = new ConcurrentStack<string>(); 2:  3: // adding to stack is much the same as before 4: stack.Push("First"); 5:  6: // but you can also push multiple items in one atomic operation (no interleaves) 7: stack.PushRange(new [] { "Second", "Third", "Fourth" }); For looking at the top item of the stack (without removing it) the Peek() method has been removed in favor of a TryPeek().  This is because in order to do a peek the stack must be non-empty, but between the time you check for empty and the time you execute the peek the stack contents may have changed.  Thus the TryPeek() was created to be an atomic check for empty, and then peek if not empty: 1: // to look at top item of stack without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (stack.TryPeek(out item)) 5: { 6: Console.WriteLine("Top item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Stack was empty."); 11: } Finally, to remove items from the stack, we have the TryPop() for single, and TryPopRange() for multiple items.  Just like the TryPeek(), these operations replace Pop() since we need to ensure atomically that the stack is non-empty before we pop from it: 1: // to remove items, use TryPop or TryPopRange to get multiple items atomically (no interleaves) 2: if (stack.TryPop(out item)) 3: { 4: Console.WriteLine("Popped " + item); 5: } 6:  7: // TryPopRange will only pop up to the number of spaces in the array, the actual number popped is returned. 8: var poppedItems = new string[2]; 9: int numPopped = stack.TryPopRange(poppedItems); 10:  11: foreach (var theItem in poppedItems.Take(numPopped)) 12: { 13: Console.WriteLine("Popped " + theItem); 14: } Finally, note that as stated before, GetEnumerator() and ToArray() gets a snapshot of the data at the time of the call.  That means if you are enumerating the stack you will get a snapshot of the stack at the time of the call.  This is illustrated below: 1: var stack = new ConcurrentStack<string>(); 2:  3: // adding to stack is much the same as before 4: stack.Push("First"); 5:  6: var results = stack.GetEnumerator(); 7:  8: // but you can also push multiple items in one atomic operation (no interleaves) 9: stack.PushRange(new [] { "Second", "Third", "Fourth" }); 10:  11: while(results.MoveNext()) 12: { 13: Console.WriteLine("Stack only has: " + results.Current); 14: } The only item that will be printed out in the above code is "First" because the snapshot was taken before the other items were added. This may sound like an issue, but it’s really for safety and is more correct.  You don’t want to enumerate a stack and have half a view of the stack before an update and half a view of the stack after an update, after all.  In addition, note that this is still thread-safe, whereas iterating through a non-concurrent collection while updating it in the old collections would cause an exception. ConcurrentQueue<T>: The thread-safe FIFO container The ConcurrentQueue<T> is the thread-safe counterpart of the System.Collections.Generic.Queue<T> class.  The concurrent queue uses an underlying list of small arrays and lock-free System.Threading.Interlocked operations on the head and tail arrays.  Once again, this allows us to do thread-safe operations without the need for heavy locks! The ConcurrentQueue<T> (like the ConcurrentStack<T>) has some departures from the non-concurrent counterpart.  Most notably: Dequeue() was removed in favor of TryDequeue(). Returns true if an item existed and was dequeued and false if empty. Count does not take a snapshot It subtracts the head and tail index to get the count.  This results overall in a O(1) complexity which is quite good.  It’s still recommended, however, that for empty checks you call IsEmpty instead of comparing Count to zero. ToArray() and GetEnumerator() both take snapshots. This means that iteration over a queue will give you a static view at the time of the call and will not reflect updates. The Enqueue() method on the ConcurrentQueue<T> works much the same as the generic Queue<T>: 1: var queue = new ConcurrentQueue<string>(); 2:  3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5: queue.Enqueue("Second"); 6: queue.Enqueue("Third"); For front item access, the TryPeek() method must be used to attempt to see the first item if the queue.  There is no Peek() method since, as you’ll remember, we can only peek on a non-empty queue, so we must have an atomic TryPeek() that checks for empty and then returns the first item if the queue is non-empty. 1: // to look at first item in queue without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (queue.TryPeek(out item)) 5: { 6: Console.WriteLine("First item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Queue was empty."); 11: } Then, to remove items you use TryDequeue().  Once again this is for the same reason we have TryPeek() and not Peek(): 1: // to remove items, use TryDequeue. If queue is empty returns false. 2: if (queue.TryDequeue(out item)) 3: { 4: Console.WriteLine("Dequeued first item " + item); 5: } Just like the concurrent stack, the ConcurrentQueue<T> takes a snapshot when you call ToArray() or GetEnumerator() which means that subsequent updates to the queue will not be seen when you iterate over the results.  Thus once again the code below will only show the first item, since the other items were added after the snapshot. 1: var queue = new ConcurrentQueue<string>(); 2:  3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5:  6: var iterator = queue.GetEnumerator(); 7:  8: queue.Enqueue("Second"); 9: queue.Enqueue("Third"); 10:  11: // only shows First 12: while (iterator.MoveNext()) 13: { 14: Console.WriteLine("Dequeued item " + iterator.Current); 15: } Using collections concurrently You’ll notice in the examples above I stuck to using single-threaded examples so as to make them deterministic and the results obvious.  Of course, if we used these collections in a truly multi-threaded way the results would be less deterministic, but would still be thread-safe and with no locking on your part required! For example, say you have an order processor that takes an IEnumerable<Order> and handles each other in a multi-threaded fashion, then groups the responses together in a concurrent collection for aggregation.  This can be done easily with the TPL’s Parallel.ForEach(): 1: public static IEnumerable<OrderResult> ProcessOrders(IEnumerable<Order> orderList) 2: { 3: var proxy = new OrderProxy(); 4: var results = new ConcurrentQueue<OrderResult>(); 5:  6: // notice that we can process all these in parallel and put the results 7: // into our concurrent collection without needing any external locking! 8: Parallel.ForEach(orderList, 9: order => 10: { 11: var result = proxy.PlaceOrder(order); 12:  13: results.Enqueue(result); 14: }); 15:  16: return results; 17: } Summary Obviously, if you do not need multi-threaded safety, you don’t need to use these collections, but when you do need multi-threaded collections these are just the ticket! The plethora of features (I always think of the movie The Three Amigos when I say plethora) built into these containers and the amazing way they acheive thread-safe access in an efficient manner is wonderful to behold. Stay tuned next week where we’ll continue our discussion with the ConcurrentBag<T> and the ConcurrentDictionary<TKey,TValue>. For some excellent information on the performance of the concurrent collections and how they perform compared to a traditional brute-force locking strategy, see this wonderful whitepaper by the Microsoft Parallel Computing Platform team here.   Tweet Technorati Tags: C#,.NET,Concurrent Collections,Collections,Multi-Threading,Little Wonders,BlackRabbitCoder,James Michael Hare

    Read the article

  • Skinny controller in ASP.NET MVC 4

    - by thangchung
    Rails community are always inspire a lot of best ideas. I really love this community by the time. One of these is "Fat models and skinny controllers". I have spent a lot of time on ASP.NET MVC, and really I did some miss-takes, because I made the controller so fat. That make controller is really dirty and very hard to maintain in the future. It is violate seriously SRP principle and KISS as well. But how can we achieve that in ASP.NET MVC? That question is really clear after I read "Manning ASP.NET MVC 4 in Action". It is simple that we can separate it into ActionResult, and try to implementing logic and persistence data inside this. In last 2 years, I have read this from Jimmy Bogard blog, but in that time I never had a consideration about it. That's enough for talking now. I just published a sample on ASP.NET MVC 4, implemented on Visual Studio 2012 RC at here. I used EF framework at here for implementing persistence layer, and also use 2 free templates from internet to make the UI for this sample. In this sample, I try to implementing the simple magazine website that managing all articles, categories and news. It is not finished at all in this time, but no problems, because I just show you about how can we make the controller skinny. And I wanna hear more about your ideas. The first thing, I am abstract the base ActionResult class like this:    public abstract class MyActionResult : ActionResult, IEnsureNotNull     {         public abstract void EnsureAllInjectInstanceNotNull();     }     public abstract class ActionResultBase<TController> : MyActionResult where TController : Controller     {         protected readonly Expression<Func<TController, ActionResult>> ViewNameExpression;         protected readonly IExConfigurationManager ConfigurationManager;         protected ActionResultBase (Expression<Func<TController, ActionResult>> expr)             : this(DependencyResolver.Current.GetService<IExConfigurationManager>(), expr)         {         }         protected ActionResultBase(             IExConfigurationManager configurationManager,             Expression<Func<TController, ActionResult>> expr)         {             Guard.ArgumentNotNull(expr, "ViewNameExpression");             Guard.ArgumentNotNull(configurationManager, "ConfigurationManager");             ViewNameExpression = expr;             ConfigurationManager = configurationManager;         }         protected ViewResult GetViewResult<TViewModel>(TViewModel viewModel)         {             var m = (MethodCallExpression)ViewNameExpression.Body;             if (m.Method.ReturnType != typeof(ActionResult))             {                 throw new ArgumentException("ControllerAction method '" + m.Method.Name + "' does not return type ActionResult");             }             var result = new ViewResult             {                 ViewName = m.Method.Name             };             result.ViewData.Model = viewModel;             return result;         }         public override void ExecuteResult(ControllerContext context)         {             EnsureAllInjectInstanceNotNull();         }     } I also have an interface for validation all inject objects. This interface make sure all inject objects that I inject using Autofac container are not null. The implementation of this as below public interface IEnsureNotNull     {         void EnsureAllInjectInstanceNotNull();     } Afterwards, I am just simple implementing the HomePageViewModelActionResult class like this public class HomePageViewModelActionResult<TController> : ActionResultBase<TController> where TController : Controller     {         #region variables & ctors         private readonly ICategoryRepository _categoryRepository;         private readonly IItemRepository _itemRepository;         private readonly int _numOfPage;         public HomePageViewModelActionResult(Expression<Func<TController, ActionResult>> viewNameExpression)             : this(viewNameExpression,                    DependencyResolver.Current.GetService<ICategoryRepository>(),                    DependencyResolver.Current.GetService<IItemRepository>())         {         }         public HomePageViewModelActionResult(             Expression<Func<TController, ActionResult>> viewNameExpression,             ICategoryRepository categoryRepository,             IItemRepository itemRepository)             : base(viewNameExpression)         {             _categoryRepository = categoryRepository;             _itemRepository = itemRepository;             _numOfPage = ConfigurationManager.GetAppConfigBy("NumOfPage").ToInteger();         }         #endregion         #region implementation         public override void ExecuteResult(ControllerContext context)         {             base.ExecuteResult(context);             var cats = _categoryRepository.GetCategories();             var mainViewModel = new HomePageViewModel();             var headerViewModel = new HeaderViewModel();             var footerViewModel = new FooterViewModel();             var mainPageViewModel = new MainPageViewModel();             headerViewModel.SiteTitle = "Magazine Website";             if (cats != null && cats.Any())             {                 headerViewModel.Categories = cats.ToList();                 footerViewModel.Categories = cats.ToList();             }             mainPageViewModel.LeftColumn = BindingDataForMainPageLeftColumnViewModel();             mainPageViewModel.RightColumn = BindingDataForMainPageRightColumnViewModel();             mainViewModel.Header = headerViewModel;             mainViewModel.DashBoard = new DashboardViewModel();             mainViewModel.Footer = footerViewModel;             mainViewModel.MainPage = mainPageViewModel;             GetViewResult(mainViewModel).ExecuteResult(context);         }         public override void EnsureAllInjectInstanceNotNull()         {             Guard.ArgumentNotNull(_categoryRepository, "CategoryRepository");             Guard.ArgumentNotNull(_itemRepository, "ItemRepository");             Guard.ArgumentMustMoreThanZero(_numOfPage, "NumOfPage");         }         #endregion         #region private functions         private MainPageRightColumnViewModel BindingDataForMainPageRightColumnViewModel()         {             var mainPageRightCol = new MainPageRightColumnViewModel();             mainPageRightCol.LatestNews = _itemRepository.GetNewestItem(_numOfPage).ToList();             mainPageRightCol.MostViews = _itemRepository.GetMostViews(_numOfPage).ToList();             return mainPageRightCol;         }         private MainPageLeftColumnViewModel BindingDataForMainPageLeftColumnViewModel()         {             var mainPageLeftCol = new MainPageLeftColumnViewModel();             var items = _itemRepository.GetNewestItem(_numOfPage);             if (items != null && items.Any())             {                 var firstItem = items.First();                 if (firstItem == null)                     throw new NoNullAllowedException("First Item".ToNotNullErrorMessage());                 if (firstItem.ItemContent == null)                     throw new NoNullAllowedException("First ItemContent".ToNotNullErrorMessage());                 mainPageLeftCol.FirstItem = firstItem;                 if (items.Count() > 1)                 {                     mainPageLeftCol.RemainItems = items.Where(x => x.ItemContent != null && x.Id != mainPageLeftCol.FirstItem.Id).ToList();                 }             }             return mainPageLeftCol;         }         #endregion     }  Final step, I get into HomeController and add some line of codes like this [Authorize]     public class HomeController : BaseController     {         [AllowAnonymous]         public ActionResult Index()         {             return new HomePageViewModelActionResult<HomeController>(x=>x.Index());         }         [AllowAnonymous]         public ActionResult Details(int id)         {             return new DetailsViewModelActionResult<HomeController>(x => x.Details(id), id);         }         [AllowAnonymous]         public ActionResult Category(int id)         {             return new CategoryViewModelActionResult<HomeController>(x => x.Category(id), id);         }     } As you see, the code in controller is really skinny, and all the logic I move to the custom ActionResult class. Some people said, it just move the code out of controller and put it to another class, so it is still hard to maintain. Look like it just move the complicate codes from one place to another place. But if you have a look and think it in details, you have to find out if you have code for processing all logic that related to HttpContext or something like this. You can do it on Controller, and try to delegating another logic  (such as processing business requirement, persistence data,...) to custom ActionResult class. Tell me more your thinking, I am really willing to hear all of its from you guys. All source codes can be find out at here. Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="http://weblogs.asp.net//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs");

    Read the article

< Previous Page | 264 265 266 267 268 269  | Next Page >