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  • Seed has_many relation using mass assignment

    - by rnd
    Here are my two models: class Article < ActiveRecord::Base attr_accessible :content has_many :comments end class Comment < ActiveRecord::Base attr_accessible :content belongs_to :article end And I'm trying to seed the database in seed.rb using this code: Article.create( [{ content: "Hi! This is my first article!", comments: [{content: "It sucks"}, {content: "Best article ever!"}] }], without_protection: true) However rake db:seed gives me the following error message: rake aborted! Comment(#28467560) expected, got Hash(#13868840) Tasks: TOP => db:seed (See full trace by running task with --trace) It is possible to seed the database like this? If yes a follow-up question: I've searched some and it seems that to do this kind of (nested?) mass assignment I need to add 'accepts_nested_attributes_for' for the attributes I want to assign. (Possibly something like 'accepts_nested_attributes_for :article' for the Comment model) Is there a way to allow this similar to the 'without_protection: true'? Because I only want to accept this kind of mass assignment when seeding the database.

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  • Help getting MVVM ViewModel to bind to the View

    - by cw
    Okay guys, I'm new to this model and Silverlight in general. I have the following code (changed object names, so syntax/spelling errors ignore). public class ViewModel { ViewModelSource m_vSource; public ViewModel(IViewModelSource source) { m_vSource= source; m_vSource.ItemArrived += new Action<Item>(m_vSource_ItemArrived); } void m_vSource_ItemArrived(Item obj) { Title = obj.Title; Subitems = obj.items; Description = obj.Description; } public void GetFeed(string serviceUrl) { m_vFeedSource.GetFeed(serviceUrl); } public string Title { get; set; } public IEnumerable<Subitems> Subitems { get; set; } public string Description { get; set; } } Here is the code I have in my page's codebehind. ViewModel m_vViewModel; public MainPage() { InitializeComponent(); m_vViewModel = new ViewModel(new ViewModelSource()); this.Loaded += new RoutedEventHandler(MainPage_Loaded); this.DataContext = m_vViewModel; } void MainPage_Loaded(object sender, RoutedEventArgs e) { m_vViewModel.GetItems("http://www.myserviceurl.com"); } Finally, here is a sample of what my xaml looks like. <!--TitleGrid is the name of the application and page title--> <Grid x:Name="TitleGrid" Grid.Row="0"> <TextBlock Text="My Super Title" x:Name="textBlockPageTitle" Style="{StaticResource PhoneTextPageTitle1Style}"/> <TextBlock Text="{Binding Path=Title}" x:Name="textBlockListTitle" Style="{StaticResource PhoneTextPageTitle2Style}"/> </Grid> I know I'm missing something, but I'm just not knowledgable enough which is why I'm asking you guys :) Is there anything I'm doing wrong here? Thanks!

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  • When to choose which machine learning classifier?

    - by LM
    Suppose I'm working on some classification problem. (Fraud detection and comment spam are two problems I'm working on right now, but I'm curious about any classification task in general.) How do I know which classifier I should use? (Decision tree, SVM, Bayesian, logistic regression, etc.) In which cases is one of them the "natural" first choice, and what are the principles for choosing that one? Examples of the type of answers I'm looking for (from Manning et al.'s "Introduction to Information Retrieval book": http://nlp.stanford.edu/IR-book/html/htmledition/choosing-what-kind-of-classifier-to-use-1.html): a. If your data is labeled, but you only have a limited amount, you should use a classifier with high bias (for example, Naive Bayes). [I'm guessing this is because a higher-bias classifier will have lower variance, which is good because of the small amount of data.] b. If you have a ton of data, then the classifier doesn't really matter so much, so you should probably just choose a classifier with good scalability. What are other guidelines? Even answers like "if you'll have to explain your model to some upper management person, then maybe you should use a decision tree, since the decision rules are fairly transparent" are good. I care less about implementation/library issues, though. Also, for a somewhat separate question, besides standard Bayesian classifiers, are there 'standard state-of-the-art' methods for comment spam detection (as opposed to email spam)? [Not sure if stackoverflow is the best place to ask this question, since it's more machine learning than actual programming -- if not, any suggestions for where else?]

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  • MVC: Submit one form from a page with multiple forms

    - by Rob
    I'm working in an ASP.NET 3.5 MVC application where i've got a view with multiple forms in it. Form 1 contains information about products and will form a shoppingcart with a remove button. Form 2 is as below and is to be used to get the information from the shoppingcart and create an order of it. <% using (Html.BeginForm()) { %> <%=Html.Hidden(Order.ProductId", "E63EF586-F625-4C8D-B82E-E63A6FA4A63C")%> <%=Html.Hidden(Order.Amount", 1)%> <input type="submit" value="Pay" /> <%} % The first form contains a similar beginform with a foreach loop to get the information about the products from the model. When i use the submit button on the second form everything seems to be submitted and the action in the controller for the first form is trying to handle the request. That is where the error occurce because the information in the viewmodel isn't corresponding to what is being expected. The controller which is trying to handle the request: [AcceptVerbs(HttpVerbs.Post)] public ActionResult ShowShoppingcartForm([Bind(Prefix = "Order")] MyViewmodel viewModel) { //.. } The controller which is expected to handle the request: [AcceptVerbs(HttpVerbs.Post)] public ActionResult SaveOrder([Bind(Prefix = "Order")] MyViewmodel viewModel) { throw new NotImplementedException(); }

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  • Compile Assembly Output generated by VC++?

    - by SDD
    I have a simple hello world C program and compile it with /FA. As a consequence, the compiler also generates the corresponding assembly listing. Now I want to use masm/link to assemble an executable from the generated .asm listing. The following command line yields 3 linker errors: \masm32\bin\ml /I"C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\include" /c /coff asm_test.asm \masm32\bin\link /SUBSYSTEM:CONSOLE /LIBPATH:"C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\lib" asm_test.obj indicating that the C-runtime functions were not linked to the object files produced earlier: asm_test.obj : error LNK2001: unresolved external symbol @__security_check_cookie@4 asm_test.obj : error LNK2001: unresolved external symbol _printf LINK : error LNK2001: unresolved external symbol _wmainCRTStartup asm_test.exe : fatal error LNK1120: 3 unresolved externals Here is the generated assembly listing ; Listing generated by Microsoft (R) Optimizing Compiler Version 15.00.30729.01 TITLE c:\asm_test\asm_test\asm_test.cpp .686P .XMM include listing.inc .model flat INCLUDELIB OLDNAMES PUBLIC ??_C@_0O@OBPALAEI@hello?5world?$CB?6?$AA@ ; `string' EXTRN @__security_check_cookie@4:PROC EXTRN _printf:PROC ; COMDAT ??_C@_0O@OBPALAEI@hello?5world?$CB?6?$AA@ CONST SEGMENT ??_C@_0O@OBPALAEI@hello?5world?$CB?6?$AA@ DB 'hello world!', 0aH, 00H ; `string' CONST ENDS PUBLIC _wmain ; Function compile flags: /Ogtpy ; COMDAT _wmain _TEXT SEGMENT _argc$ = 8 ; size = 4 _argv$ = 12 ; size = 4 _wmain PROC ; COMDAT ; File c:\users\octon\desktop\asm_test\asm_test\asm_test.cpp ; Line 21 push OFFSET ??_C@_0O@OBPALAEI@hello?5world?$CB?6?$AA@ call _printf add esp, 4 ; Line 22 xor eax, eax ; Line 23 ret 0 _wmain ENDP _TEXT ENDS END I am using the latest masm32 version (6.14.8444).

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  • backbone.js removing template from DOM upon success

    - by timpone
    I'm writing a simple message board app to learn backbone. It's going ok (a lot of the use of this isn't making sense) but am a little stuck in terms of how I would remove a form / html from the dom. I have included most of the code but you can see about 4 lines up from the bottom, the part that isn't working. How would I remove this from the DOM? thx in advance var MbForm=Backbone.View.extend({ events: { 'click button.add-new-post': 'savePost' }, el: $('#detail'), template:_.template($('#post-add-edit-tmpl').html()), render: function(){ var compiled_template = this.template(); this.$el.html(compiled_template); return this; }, savePost: function(e){ //var self=this; //console.log("I want you to say Hello!"); data={ header: $('#post_header').val(), detail: $('#post_detail').val(), forum_id: $('#forum_id').val(), post_id: $('#post_id').val(), parent_id: $('#parent_id').val() }; this.model.save(data, { success: function(){ alert('this saved'); //$(this.el).html('this is what i want'); this.$el.remove();// <- this is the part that isn't working /* none of these worked - error Uncaught TypeError: Cannot call method 'unbind' of undefined this.$el.unbind(); this.$el.empty(); this.el.unbind(); this.el.empty(); */ //this.unbind(); //self.append('this is appended'); } });

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  • Overriding to_xml for collection of ActiveRecord objects

    - by Chirantan
    Okay, I know you can override the to_xml method for a single instance of ActiveRecord object and it works just fine for me. But how would I go about overriding the to_xml method for collection of objects? Suppose for Task model instance, I implemented to_xml which looks like this. def to_xml super(:methods => [:tag_list], :include => {:project => {:include => {:folder => {}}}, :folder => {}}) end Works just fine when a single task is to be serialized to xml. But when my code runs for collection of tasks, like in the following piece of code render :xml => @tasks.to_xml I get wrong number of arguments (1 for 0) /home/chirantan/.gem/ruby/1.8/gems/activesupport-2.3.5/lib/active_support/core_ext/array/conversions.rb:189:in `to_xml' /home/chirantan/.gem/ruby/1.8/gems/activesupport-2.3.5/lib/active_support/core_ext/array/conversions.rb:189:in `to_xml' /home/chirantan/.gem/ruby/1.8/gems/activesupport-2.3.5/lib/active_support/core_ext/array/conversions.rb:189:in `each' /home/chirantan/.gem/ruby/1.8/gems/activesupport-2.3.5/lib/active_support/core_ext/array/conversions.rb:189:in `to_xml' /var/lib/gems/1.8/gems/builder-2.1.2/lib/builder/xmlbase.rb:134:in `call' /var/lib/gems/1.8/gems/builder-2.1.2/lib/builder/xmlbase.rb:134:in `_nested_structures' /var/lib/gems/1.8/gems/builder-2.1.2/lib/builder/xmlbase.rb:58:in `method_missing' /var/lib/gems/1.8/gems/builder-2.1.2/lib/builder/xmlbase.rb:31:in `tag!' /~/blah/app/controllers/tasks_controller.rb:412:in `completed' How do I make this work?

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  • Declaring a string array in class header file - compiler thinks string is variable name?

    - by Dave
    Hey everybody, I need a bit of a hand with declaring a string array in my class header file in C++. atm it looks like this: //Maze.h #include <string> class Maze { GLfloat mazeSize, mazeX, mazeY, mazeZ; string* mazeLayout; public: Maze ( ); void render(); }; and the constructor looks like this: //Maze.cpp #include <GL/gl.h> #include "Maze.h" #include <iostream> #include <fstream> Maze::Maze( ) { cin >> mazeSize; mazeLayout = new string[mazeSize]; mazeX = 2/mazeSize; mazeY = 0.25; mazeZ = 2/mazeSize; } I'm getting a compiler error that says: In file included from model-view.cpp:11: Maze.h:14: error: ISO C++ forbids declaration of ‘string’ with no type Maze.h:14: error: expected ‘;’ before ‘*’ token and the only sense that makes to me is that for some reason it thinks I want string as a variable name not as a type declaration. If anybody could help me out that would be fantastic, been looking this up for a while and its giving me the shits lol. Cheers guys

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  • How to tell which dataform button ended edit when using EventToCommand

    - by Rodd
    I'm new to SilverLight and Mvvm-Light. I have a DataForm on my view that displays/edits a SelectedPerson property (a Person object) of my view model. I want to execute a command on my viewmodel when the user clicks the Save button but don't want to take action if the user clicks cancel. I added the following to my ViewModel: public RelayCommand PersonEditEnded {get; set;} ... public void Initialize() { PersonEditEnded = new RelayCommand(DoSomething); ... } public void DoSomething() { } I added the following to my View: <toolkit:DataForm x:Name="PersonForm" ... CurrentItem="{Binding SelectedPerson, Mode=TwoWay}"> <i:Interaction.Triggers> <i:EventTrigger EventName="EditEnded"> <gs:EventToCommand Command="{Binding PersonEditEnded, Mode=OneWay}"/> </i:EventTrigger> </i:Interaction.Triggers> </toolkit:DataForm> This works and the DoSomething method is being called when the user presses Submit. However, DoSomething is also called when user presses Cancel. Is there a way to know which button was pressed or to supress the call when Cancel is pressed? Thanks for whatever help you can offer!

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  • Ditching Django's models for Ajax/Web Services

    - by Igor Ganapolsky
    Recently I came across a problem at work that made me rethink Django's models. The app I am developing resides on a Linux server. Its a simple model/view/controller app that involves user interaction and updating data in the database. The problem is that this data resides in a MS SQL database on a Windows machine. So in order to use Django's models, I would have to leverage an ODBC driver on linux, and the use a python add-on like pyodbc. Well, let me tell you, setting up a reliable and functional ODBC connection on linux is no easy feat! So much so, that I spent several hours maneuvering this on my CentOS with no luck, and was left with frustration and lots of dumb system errors. In the meantime I have a deadline to meet, and suddenly the very agile and rapid Django application is a roadblock rather than a pleasure to work with. Someone on my team suggested writing this app in .NET. But there are a few problems with that: it won't be deployable on a linux machine, and I won't be able to work on it since I don't know ASP.net. Then a much better suggestion was made: keep the app in django, but instead of using models, do straight up ajax/web services calls in the template. And then it dawned on me - what a great idea. Django's models seem like a nuissance and hindrance in this case, and I can just have someone else write .Net services on their side, that I can call from my template. As a result my app will be leaner and more compact. So, I was wondering if you guys ever came across a similar dillema and what you decided to do about it.

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  • How much detail should be in a project plan or spec?

    - by DeanMc
    I have an issue that I feel many programmers can relate to... I have worked on many small scale projects. After my initial paper brain storm I tend to start coding. What I come up with is usually a rough working model of the actual application. I design in a disconnected fashion so I am talking about underlying code libraries, user interfaces are the last thing as the library usually dictates what is needed in the UI. As my projects get bigger I worry that so should my "spec" or design document. The above paragraph, from my investigations, is echoed all across the internet in one fashion or another. When a UI is concerned there is a bit more information but it is UI specific and does not relate to code libraries. What I am beginning to realise is that maybe code is code is code. It seems from my extensive research that there is no 1:1 mapping between a design document and the code. When I need to research a topic I dump information into OneNote and from there I prioritise features into versions and then into related chunks so that development runs in a fairly linear fashion, my tasks tend to look like so: Implement Binary File Reader Implement Binary File Writer Create Object to encapsulate Data for expression to the caller Now any programmer worth his salt is aware that between those three to do items could be a potential wall of code that could expand out to multiple files. I have tried to map the complete code process for each task but I simply don't think it can be done effectively. By the time one mangles pseudo code it is essentially code anyway so the time investment is negated. So my question is this: Am I right in assuming that the best documentation is the code itself. We are all in agreement that a high level overview is needed. How high should this be? Do you design to statement, class or concept level? What works for you?

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  • ColdFusion 9 ORM - Securing an object at a low level...

    Hiya: I wonder if anybody has an idea on this... I'm looking at securing a low level object in my model (a "member" object) so by default only certain information can be accessed from it. Here's a possible approach (damn sexy if it would work!): 1) Add a property called "locked" - defaulting to "true" to the object itself. It appears that the only option to do this, and not tie it to a db table column, is to use the formula attribute that takes a query. So to default locked to TRUE I've got: <cfproperty name="locked" formula="select 1" /> 2) Then, I overwrite the existing set-ers and get-ers to use this: e.g. <cffunction name="getFullname" returnType="string"> <cfscript> if (this.getLocked()) { return this.getScreenName(); } else { return this.getFullname(); } </cfscript> </cffunction> 3) When i use it like this: <p> #oMember.getFullName()# </p> shows the ScreenName (great!) but... When I do this: <cfset oMember.setLocked(false)> <p> #oMember.getFullName()# </p> Just hangs!!! It appears that attempting to set a property that's been defined using "formula" is a no-no. Any ideas? Any other way we can have properties attached to an ORM object that are gettable and settable without them being present in the db? Ideas appreciated!

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  • Action Mailer: How do I render dynamic data in an email body that is stored in the database?

    - by Brandon Toone
    I have Action Mailer setup to render an email using the body attribute of my Email model (in the database). I want to be able to use erb in the body but I can't figure out how to get it to render in the sent email message. I'm able to get the body as a string with this code # models/user_mailer.rb def custom_email(user, email_id) email = Email.find(email_id) recipients user.email from "Mail It Example <[email protected]>" subject "Hello From Mail It" sent_on Time.now # pulls the email body and passes a string to the template views/user_mailer/customer_email.text.html.erb body :msg => email.body end I came across this article http://rails-nutshell.labs.oreilly.com/ch05.html which says I can use render but I'm only able to get render :text to work and not render :inline # models/user_mailer.rb def custom_email(user, email_id) email = Email.find(email_id) recipients user.email from "Mail It Example <[email protected]>" subject "Hello From Mail It" sent_on Time.now # body :msg => email.body body :msg => (render :text => "Thanks for your order") # renders text and passes as a variable to the template # body :msg => (render :inline => "We shipped <%= Time.now %>") # throws a NoMethodError end

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  • Understanding many to many relationships and Entity Framework

    - by Anders Svensson
    I'm trying to understand the Entity Framework, and I have a table "Users" and a table "Pages". These are related in a many-to-many relationship with a junction table "UserPages". First of all I'd like to know if I'm designing this relationship correctly using many-to-many: One user can visit multiple pages, and each page can be visited by multiple users..., so am I right in using many2many? Secondly, and more importantly, as I have understood m2m relationships, the User and Page tables should not repeat information. I.e. there should be only one record for each user and each page. But then in the entity framework, how am I able to add new visits to the same page for the same user? That is, I was thinking I could simply use the Count() method on the IEnumerable returned by a LINQ query to get the number of times a user has visited a certain page. But I see no way of doing that. In Linq to Sql I could access the junction table and add records there to reflect added visits to a certain page by a certain user, as many times as necessary. But in the EF I can't access the junction table. I can only go from User to a Pages collection and vice versa. I'm sure I'm misunderstanding relationships or something, but I just can't figure out how to model this. I could always have a Count column in the Page table, but as far as I have understood you're not supposed to design database tables like that, those values should be collected by queries... Please help me understand what I'm doing wrong...

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  • How can I map stored procedure result into a custom class with linq-to-sql?

    - by Remnant
    I have a stored procedure that returns a result set (4 columns x n Rows). The data is based on multiple tables within my database and provides a summary for each department within a corporate. Here is sample: usp_GetDepartmentSummary DeptName EmployeeCount Male Female HR 12 5 7 etc... I am using linq-to-sql to retrieve data from my database (nb - have to use sproc as it is something I have inherited). I would like to call the above sproc and map into a department class: public class Department { public string DeptName {get; set;} public int EmployeeCount {get; set;} public int MaleCount {get; set;} public int FemaleCount {get; set;} } In VS2008, I can drag and drop my sproc onto the methods pane of the linq-to-sql designer. When I examine the designer.cs the return type for this sproc is defined as: ISingleResult<usp_GetDepartmentSummaryResult> What I would like to do is amend this somehow so that it returns a Department type so that I can pass the results of the sproc as a strongly typed view: <% foreach (var dept in Model) { %> <ul> <li class="deptname"><%= dept.DeptName %></li> <li class="deptname"><%= dept.EmployeeCount %></li> etc... Any ideas how to achieve this? NB - I have tried amending the designer.cs and dbml xml file directly but with limited success. I admit to being a little out of my depth when it comes to updating those files directly and I am not sure it is best practice? Would be good to get some diretion. Thanks much

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  • [MySQL/PHP] Avoid using RAND()

    - by Andrew Ellis
    So... I have never had a need to do a random SELECT on a MySQL DB until this project I'm working on. After researching it seems the general populous says that using RAND() is a bad idea. I found an article that explains how to do another type of random select. Basically, if I want to select 5 random elements, I should do the following (I'm using the Kohana framework here)? If not, what is a better solution? Thanks, Andrew <?php final class Offers extends Model { /** * Loads a random set of offers. * * @param integer $limit * @return array */ public function random_offers($limit = 5) { // Find the highest offer_id $sql = ' SELECT MAX(offer_id) AS max_offer_id FROM offers '; $max_offer_id = DB::query(Database::SELECT, $sql) ->execute($this->_db) ->get('max_offer_id'); // Check to make sure we're not trying to load more offers // than there really is... if ($max_offer_id < $limit) { $limit = $max_offer_id; } $used = array(); $ids = ''; for ($i = 0; $i < $limit; ) { $rand = mt_rand(1, $max_offer_id); if (!isset($used[$rand])) { // Flag the ID as used $used[$rand] = TRUE; // Set the ID if ($i > 0) $ids .= ','; $ids .= $rand; ++$i; } } $sql = ' SELECT offer_id, offer_name FROM offers WHERE offer_id IN(:ids) '; $offers = DB::query(Database::SELECT, $sql) ->param(':ids', $ids) ->as_object(); ->execute($this->_db); return $offers; } }

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  • Dataset bind to Gridview within WCF REST retrieval method and Linq to Sql

    - by user643794
    I used a WCF REST template to build a WCF service library to create PUT and GET calls. PUT method works fine sending my blob to a database. On the GET, I want to be able to access the web service directly and display the results from a stored procedure as a dataset and bind this to a gridview. The stored procedure is a simple select statement, returning three of the four columns from the table. I have the following: [WebGet(UriTemplate = "/?name={name}", ResponseFormat = WebMessageFormat.Xml)] public List<Object> GetCollection(string name) { try { db.OpenDbConnection(); // Call to SQL stored procedure return db.GetCustFromName(name); } catch (Exception e) { Log.Error("Stored Proc execution failed. ", e); } finally { db.CloseDbConnection(); } return null; } I also added Linq to SQL class to include my database table and stored procedures access. I also created the Default.aspx file in addition to the other required files. protected void Page_Load(object sender, EventArgs e) { ServiceDataContext objectContext = new ServiceDataContext(); var source = objectContext.GetCustFromName("Tiger"); Menu1.DataSource = source; Menu1.DataBind(); } But this gives me The entity type '' does not belong to any registered model. Where should the data binding be done? What should be the return type for GetCollection()? I am stuck with this. Please provide help on how to do this.

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  • how to create a changing variable for fsolve

    - by Shun Miyamoto
    i want fsolve to calculate the output for different uc each time (increasing uc by 0.001 each time). each output from fsolve should be sent to a simulink model seperatly. so i set a loop to do so, but i believe that at the currenty constellation (if it will work)will just calculate 1000 different values? is there a way to send out the values seperately? if not, how can i create a parameter uc. that goes from 0 to say 1000? i tried uc=0:0.001:1000, but again, the demension doen't seem to fit. how do i create a function that takes the next element of a vector/matrix each time the function is called? uc=0; for i=0:1000 x0=[1,1,1]; y=x0(1); u=x0(2); yc=x0(3); options=optimset('Display','off'); x= fsolve(@myfun,x0,options,uc,d,spacing_amplitude,spacing_width); end best regards

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  • Checking for nil in view in Ruby on Rails

    - by seaneshbaugh
    I've been working with Rails for a while now and one thing I find myself constantly doing is checking to see if some attribute or object is nil in my view code before I display it. I'm starting to wonder if this is always the best idea. My rationale so far has been that since my application(s) rely on user input unexpected things can occur. If I've learned one thing from programming in general it's that users inputting things the programmer didn't think of is one of the biggest sources of run-time errors. By checking for nil values I'm hoping to sidestep that and have my views gracefully handle the problem. The thing is though I typically for various reasons have similar nil or invalid value checks in either my model or controller code. I wouldn't call it code duplication in the strictest sense, but it just doesn't seem very DRY. If I've already checked for nil objects in my controller is it okay if my view just assumes the object truly isn't nil? For attributes that can be nil that are displayed it makes sense to me to check every time, but for the objects themselves I'm not sure what is the best practice. Here's a simplified, but typical example of what I'm talking about: controller code def show @item = Item.find_by_id(params[:id]) @folders = Folder.find(:all, :order => 'display_order') if @item == nil or @item.folder == nil redirect_to(root_url) and return end end view code <% if @item != nil %> display the item's attributes here <% if @item.folder != nil %> <%= link_to @item.folder.name, folder_path(@item.folder) %> <% end %> <% else %> Oops! Looks like something went horribly wrong! <% end %> Is this a good idea or is it just silly?

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  • how can I save/keep-in-sync an in-memory graph of objects with the database?

    - by Greg
    Question - What is a good best practice approach for how can I save/keep-in-sync an jn-memory graph of objects with the database? Background: That is say I have the classes Node and Relationship, and the application is building up a graph of related objects using these classes. There might be 1000 nodes with various relationships between them. The application needs to query the structure hence an in-memory approach is good for performance no doubt (e.g. traverse the graph from Node X to find the root parents) The graph does need to be persisted however into a database with tables NODES and RELATIONSHIPS. Therefore what is a good best practice approach for how can I save/keep-in-sync an jn-memory graph of objects with the database? Ideal requirements would include: build up changes in-memory and then 'save' afterwards (mandatory) when saving, apply updates to database in correct order to avoid hitting any database constraints (mandatory) keep persistence mechanism separate from model, for ease in changing persistence layer if needed, e.g. don't just wrap an ADO.net DataRow in the Node and Relationship classes (desirable) mechanism for doing optimistic locking (desirable) Or is the overhead of all this for a smallish application just not worth it and I should just hit the database each time for everything? (assuming the response times were acceptable) [would still like to avoid if not too much extra overhead to remain somewhat scalable re performance]

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  • Asp MVC - "The Id field is required" validation message on Create; Id not set to [Required]

    - by burnt_hand
    This is happening when I try to create the entity using a Create style action in Asp.Net MVC 2. The POCO has the following properties: public int Id {get;set;} [Required] public string Message {get; set} On the creation of the entity, the Id is set automatically, so there is no need for it on the Create action. The ModelState says that "The Id field is required", but I haven't set that to be so. Is there something automatic going on here? EDIT - Reason Revealed The reason for the issue is answered by Brad Wilson via Paul Speranza in one of the comments below where he says (cheers Paul): You're providing a value for ID, you just didn't know you were. It's in the route data of the default route ("{controller}/{action}/{id}"), and its default value is the empty string, which isn't valid for an int. Use the [Bind] attribute on your action parameter to exclude ID. My default route was: new { controller = "Customer", action = "Edit", id = " " } // Parameter defaults EDIT - Update Model technique I actually changed the way I did this again by using TryUpdateModel and the exclude parameter array asscoiated with that. [HttpPost] public ActionResult Add(Venue collection) { Venue venue = new Venue(); if (TryUpdateModel(venue, null, null, new[] { "Id" })) { _service.Add(venue); return RedirectToAction("Index", "Manage"); } return View(collection); }

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  • Why is this CHOICE element not getting assigned in my SharePoint Field definition schema?

    - by ccornet
    I defined a new field of the type "Choice" for my web application. It will serve basically as a pseudo-lookup as its contents are defined by the value of a Text field in a list. It is initialized with a dummy choice to begin with (I'm under the impression a choice field needs at least one choice when defined), which is replaced with a real choice later on. But for some reason, this dummy choice is never actually added to the choices! Below is the XML Schema for the field in question. <Field ID="{ALICEH-ASFA-KEGU-IDLISTED}" Name="ddlSystems" Group="Lookup Columns" DisplayName="ddlSystems" Type="Choice" Sealed="FALSE" ReadOnly="FALSE" Hidden="FALSE" FillInChoice="TRUE" DisplaceOnUpgrade="TRUE"> <CHOICES> <CHOICE>BLANULL</CHOICE> </CHOICES> <Default>BLANULL</Default> </Field> Initially, I used a default choice of (a single space), but I changed it to BLANULL so that I can parse an actual word instead of a veritably empty string. Now, even after having uninstalled and reinstalled the feature with this field, I have a choice field that has (still a single space) as the only choice. Even more perplexing, BLANULL is actually listed for the default value in both the UI and the object model! What is causing this problem, and how can I circumvent it so that I don't have to manually set this dummy value each time?

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  • Adding a button or link to an inline in Django admin

    - by Lexo
    Hello, I have created the following django models: class Entry(SiteObject): parent = models.ForeignKey(Blog, related_name="entries") content = models.TextField(help_text = "The Content of the blog post") class EntryImage(models.Model): entry = models.ForeignKey(Entry, related_name="entryimages") imagewidth = models.PositiveIntegerField(editable=False,) imageheight = models.PositiveIntegerField(editable=False,) image_file = ImageWithThumbnailsField( #from sorl-thumbnail. Basically a wrapper for an ImageField that generates a thumbnail. upload_to="images/blogs", height_field="imageheight", width_field="imagewidth", help_text = "Select an image to upload.", thumbnail={'size': (360,720)}, generate_on_save=True, ) The EntryImage class shows up as an inline in the admin page for Entry. What I'd like to do is place a link or a button beside each of these inlines that does the following: Save the EntryImage Append <Image x> to the content of the Entry, where x is the number of the EntryImage. This will be replaced by the image's thumbnail using a template filter. Save the Entry Return to editing the Entry I have looked into this, but I just can't wrap my head around where I'm supposed to add this button or link. Has anyone else tried something similar? I've got JQuery available, since I'm using WYMEditor for the content field of the Entry class. Would this help? Thanks in advance, Lexo

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  • Access 2007 and Special/Unicode Characters in SQL

    - by blockcipher
    I have a small Access 2007 database that I need to be able to import data from an existing spreadsheet and put it into our new relational model. For the most part this seems to work pretty well. Part of the process is attempting to see if a record already exists in a target table using SQL. For example, if I extract book information out of the current row in the spreadsheet, it may contain a title and abstract. I use SQL to get the ID of a matching record, if it exists. This works fine except when I have data that's in a non-English language. In this case, it seems that there is some punctuation that is causing me problems. At least I think it's punctuation as I do have some fields that do not have punctuation and are non-English that do not give me any problems. Is there a built-in function that can escape these characters? Currently I have a small function that will escape the single quote character, but that isn't enough. Or, is there a list of Unicode characters that can interfere with how SQL wants data quoted? Thanks in advance.

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  • How do I set up routes to enable me to call different actions on the same controller?

    - by Remnant
    I am building my first asp.net mvc application for learning and development purposes and have come across an issue that I'd like some guidance with. Suppose I have a controller with two actions as follows: public class MyController : Controller { public ActionResult Index() { dbData = GetData("DefaultParameter") return View(dbData); } public ActionResult UpdateView(string dbParameter) { dbData = GetData("dbParameter"); return View(dbData); } } On my webpage I have the following: <% using (Html.BeginForm("UpdateView", "MyController")) %> <% { %> <div class="dropdown"><%=Html.DropDownList("Selection", Model.List, new { onchange="this.form.submit();" })%></div> <% } %> I have the following route in Global.asax: public static void RegisterRoutes(RouteCollection routes) { routes.MapRoute("Default", "{controller}", new { controller = "MyController", action = "Index"}); } The issue I am having is as follows: When I use the dropdownlist I get an error saying that /MyController/UpdateView could not be found. It therefore seems that I need to add an additional route as follows: routes.MapRoute("Default", "{controller}", new { controller = "MyController", action = "UpdateView"}); However, this causes two new issues for me: Due to the hierachy within the routing list, the similarity of the routes means that the one that appears first in the list is always executed. I don't see why I need to create another route for UpdateView. All I want to do is to retrieve new data from the database and update the view. I don't see what this has to do with the URL schema. It feels like I have gone down the wrong track here and I have missed something quite fundamental?

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