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  • At what size of data does it become beneficial to move from SQL to NoSQL?

    - by wobbily_col
    As a relational database programmer (most of the time), I read articles about how relational databases don't scale, and NoSQL solutions such as MongoDB do. As most of the databases I have developed so far have been small to mid scale, I have never had a problem that hasn't been solved by some indexing, query optimization or schema redesign. What sort of size would I expect to see MySQL struggling with. How many rows? (I know this is going to depend on the application, and type of data stored. the one that got me thing was basically a genetics database, so would have one main table, with 3 or 4 lookup tables. The main table will contain amongst other things, a chromosome reference, and a position coordinate. It will likely get queried for a number of entries between two potions on a chromosome, to see what is stored there).

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  • MySQL for Beginners course - first steps to lowering your Database TCOs

    - by Antoinette O'Sullivan
    Thinking about lowering your Database TCO by using the MySQL Server? Don't miss the chance to get training from the source! With the newly released MySQL for Beginners class, learn how this powerful relational database management system can make your life easier and more fun! This course covers all the basics and will get you on your way, with a solid foundation. This instructor led, hands-on class covers the fundamentals of SQL and relational databases, using MySQL as a teaching tool. Send information about this course release to a friend who might be considering getting started on the world's most popular small footprint database.

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  • Intro to NoSQL with RavenDB

    - by dgreen
    I did a talk on RavenDB back on 9/19/2012. Here was my abstract: "RavenDB is a document database which is gaining popularity in the 'NoSQL' movement. This session will introduce you to some non-relational concepts and describe how they compare/contrast with the relational solutions you're already familiar with. We'll go through the basics of RavenDB and show how easy it is to use from .NET” My next goal is to figure out how to post the slidedeck here (and maybe the code samples if I'm feeling ambitious). Then, the slides can be downloaded for only three easy payments of $39.99. However  for this one time special offer they are currently being given away absolutely FREE with a signup to http://meetup.trinug.org Footnote: I probably shouldn't have to say this, but my last comment about charging for my slidedeck was a joke. I have an odd sense of humor for those who don't already know me :)

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  • How to get around the Circular Reference issue with JSON and Entity

    - by DanScan
    I have been experimenting with creating a website that leverages MVC with JSON for my presentation layer and Entity framework for data model/database. My Issue comes into play with serializing my Model objects into JSON. I am using the code first method to create my database. When doing the code first method a one to many relationship (parent/child) requires the child to have a reference back to the parent. (Example code my be a typo but you get the picture) class parent { public List<child> Children{get;set;} public int Id{get;set;} } class child { public int ParentId{get;set;} [ForeignKey("ParentId")] public parent MyParent{get;set;} public string name{get;set;} } When returning a "parent" object via a JsonResult a circular reference error is thrown because "child" has a property of class parent. I have tried the ScriptIgnore attribute but I lose the ability to look at the child objects. I will need to display information in a parent child view at some point. I have tried to make base classes for both parent and child that do not have a circular reference. Unfortunately when I attempt to send the baseParent and baseChild these are read by the JSON Parser as their derived classes (I am pretty sure this concept is escaping me). Base.baseParent basep = (Base.baseParent)parent; return Json(basep, JsonRequestBehavior.AllowGet); The one solution I have come up with is to create "View" Models. I create simple versions of the database models that do not include the reference to the parent class. These view models each have method to return the Database Version and a constructor that takes the database model as a parameter (viewmodel.name = databasemodel.name). This method seems forced although it works. NOTE:I am posting here because I think this is more discussion worthy. I could leverage a different design pattern to over come this issue or it could be as simple as using a different attribute on my model. In my searching I have not seen a good method to overcome this problem. My end goal would be to have a nice MVC application that heavily leverages JSON for communicating with the server and displaying data. While maintaining a consistant model across layers (or as best as I can come up with).

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  • Data architecture for event log metrics?

    - by elliot42
    My service has a large ongoing number of user events, and we would like to do things like "count occurrence of event type T since date D." We are trying to make two basic decisions: What to store? Storing every event vs. only storing aggregates (Event log style) log every event and count them later, vs. (Time-series style) store a single aggregated "count of event E for date D" for every day Where to store the data In a relational database (particularly MySQL) In a non-relational (NoSQL) database In flat log files (collected centrally over the network via syslog-ng) What is standard practice / where can I read more about comparing the different types of systems? Additional details: The total event stream is large, potentially hundreds of thousands of entries per day But our current need is only to count certain types of events within it We don't necessarily need real-time access to the raw data or aggregation results IMHO, "log all events to files, crawl them at a later time to filter and aggregate the stream" is a pretty standard UNIX Way, but my Rails-y compatriots seem to think that nothing is real unless it's in MySQL.

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  • Why Moq is thorwing "expected Invocation on the mock at least once". Where as it is being set once,e

    - by Mohit
    Following is the code. create a class lib add the ref to NUnit framework 2.5.3.9345 and Moq.dll 4.0.0.0 and paste the following code. Try running it on my machine it throws TestCase 'MoqTest.TryClassTest.IsMessageNotNull' failed: Moq.MockException : Expected invocation on the mock at least once, but was never performed: v = v.Model = It.Is(value(Moq.It+<c__DisplayClass21[MoqTest.GenInfo]).match) at Moq.Mock.ThrowVerifyException(IProxyCall expected, Expression expression, Times times, Int32 callCount) at Moq.Mock.VerifyCalls(Interceptor targetInterceptor, MethodCall expected, Expression expression, Times times) at Moq.Mock.VerifySet[T](Mock1 mock, Action1 setterExpression, Times times, String failMessage) at Moq.Mock1.VerifySet(Action`1 setterExpression) Class1.cs(22,0): at MoqTest.TryClassTest.IsMessageNotNull() using System; using System.Collections.Generic; using System.Linq; using System.Text; using Moq; using NUnit.Framework; namespace MoqTest { [TestFixture] public class TryClassTest { [Test] public void IsMessageNotNull() { var mockView = new Mock<IView<GenInfo>>(); mockView.Setup(v => v.ModuleId).Returns(""); TryPresenter tryPresenter = new TryPresenter(mockView.Object); tryPresenter.SetMessage(new object(), new EventArgs()); // mockView.VerifySet(v => v.Message, Times.AtLeastOnce()); mockView.VerifySet(v => v.Model = It.Is<GenInfo>(x => x != null)); } } public class TryPresenter { private IView<GenInfo> view; public TryPresenter(IView<GenInfo> view) { this.view = view; } public void SetMessage(object sender, EventArgs e) { this.view.Model = null; } } public class MyView : IView<GenInfo> { #region Implementation of IView<GenInfo> public string ModuleId { get; set; } public GenInfo Model { get; set; } #endregion } public interface IView<T> { string ModuleId { get; set; } T Model { get; set; } } public class GenInfo { public String Message { get; set; } } } And if you change one line mockView.VerifySet(v = v.Model = It.Is(x = x != null)); to mockView.VerifySet(v = v.Model, Times.AtLeastOnce()); it works fine. I think Exception is incorrect.

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  • Attempting to update multiple partial views from a single Ajax.ActionLink

    - by mwright
    I have a a partial view which contains other partial views. I am trying to the main partial view ( "MainPartialView" ) from an Ajax.ActionLink in a partial view contained by the main partial view ( "DetailsView" ). Everything appears to be called just fine and I can step through and it executes all of the code on the pages. However, after that is all done it throws this error in a popup box in visual studio: htmlfile: Unknown runtime error This error puts the break point in the MicrosoftAjax.js file, Line 5, Col 83,632, Ch 83632. Any thoughts? Index Page: <script src="../../Scripts/MicrosoftAjax.js" type="text/javascript"></script> <script src="../../Scripts/MicrosoftMvcAjax.js" type="text/javascript"></script> <ul> <% foreach (DomainObject domainObject in Model) { %> <% Html.RenderPartial("MainPartialView", domainObject); %> <% } %> </ul> MainPartialView: <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<DomainObject>" %> <li> <div id="<%= Model.Id%>"> <%= Ajax.ActionLink("Details", "PartialViewAction", "PartialViewController", new { id = Model.Id, }, new AjaxOptions { UpdateTargetId ="UpdateTargetId" })%> <% Html.RenderPartial("Details", Model); %> <div id="Details"></div> </div> </li> Details: <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<DomainObject>" %> <% foreach ( var link in Model.Links) {%> <div> <div> <%= link.Name %> </div> <div> <%= Ajax.ActionLink("Submit this Action", "DoAction", "XTrademark", new { id = Model.TrademarkId, id2 = actionStateLink.ActionStateLinkId }, new AjaxOptions{ UpdateTargetId = Model.TrademarkId.ToString()} )%> </div> </div> <br /> <%} %>

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  • MVC 2 View Layout CSS Control Layout

    - by Cory Mathewson
    I'm new to a lot of what I'm trying to do with the development of a new MVC2 web application so this is a beginner question. I need to understand my options for control and content layout on a web page. I’m using MVC2 so I’m using Controllers, Views, ViewModels, and View Templates. What I need to spin up on…fast…is control the granular layout of controls and content on any particular view. Below I’ve pasted two examples of auto generated templates that illustrate my challenge. I see that layout is controlled by CSS in my Site.css document. In the first example I get a sequential flow of DisplayLabel and DisplayField. I prefer the adjacent layout of DisplayLabel on the same line as DisplayField produced from example 2. However, example 2 is too simple because the formatting is applied to the Label and the Field. I think the correct way to tackle this learning curve is Microsoft Expression but I don’t have personal bandwidth at the moment to tackle Expression. Can anyone point me to a resource that will expose me to lots of examples for CSS formatting? I have lots of syntax questions. For instance, I believe is referencing the Site.css but I can’t find a "display-label" section in Site.css. Example 1 <fieldset> <legend>Fields</legend> <div class="display-label">DocTitle</div> <div class="display-field"><%: Model.DocTitle %></div> <div class="display-label">DocoumentPropertiesID</div> <div class="display-field"><%: Model.DocumentPropertiesID %></div> Example 2 <h2>Title: <%: Model.DocTitle %></h2> <h2>Created: <%: Model.Created %></h2> <h2>Modified: <%: Model.Modified %></h2> <h2>Author: <%: Model.tbl_Author.Name %></h2> <h2>Genre: <%: Model.tbl_DocumentGenre.GenreName %></h2>

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  • Why is ListBoxFor not selecting items, but ListBox is?

    - by Roger Rogers
    I have the following code in my view: <%= Html.ListBoxFor(c => c.Project.Categories, new MultiSelectList(Model.Categories, "Id", "Name", new List<int> { 1, 2 }))%> <%= Html.ListBox("MultiSelectList", new MultiSelectList(Model.Categories, "Id", "Name", new List<int> { 1, 2 }))%> The only difference is that the first helper is strongly typed (ListBoxFor), and it fails to show the selected items (1,2), even though the items appear in the list, etc. The simpler ListBox is working as expected. I'm obviously missing something here. I can use the second approach, but this is really bugging me and I'd like to figure it out. For reference, my model is: public class ProjectEditModel { public Project Project { get; set; } public IEnumerable<Project> Projects { get; set; } public IEnumerable<Client> Clients { get; set; } public IEnumerable<Category> Categories { get; set; } public IEnumerable<Tag> Tags { get; set; } public ProjectSlide SelectedSlide { get; set; } } Update I just changed the ListBox name to Project.Categories (matching my model) and it now FAILS to select the item. <%= Html.ListBox("Project.Categories", new MultiSelectList(Model.Categories, "Id", "Name", new List<int> { 1, 2 }))%> I'm obviously not understanding the magic that is happening here. Update 2 Ok, this is purely naming, for example, this works... <%= Html.ListBox("Project_Tags", new MultiSelectList(Model.Tags, "Id", "Name", Model.Project.Tags.Select(t => t.Id)))%> ...because the field name is Project_Tags, not Project.Tags, in fact, anything other than Tags or Project.Tags will work. I don't get why this would cause a problem (other than that it matches the entity name), and I'm not good enough at this to be able to dig in and find out.

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  • Why Moq is throwing "expected Invocation on the mock at least once". Where as it is being set once,e

    - by Mohit
    Following is the code. create a class lib add the ref to NUnit framework 2.5.3.9345 and Moq.dll 4.0.0.0 and paste the following code. Try running it on my machine it throws TestCase 'MoqTest.TryClassTest.IsMessageNotNull' failed: Moq.MockException : Expected invocation on the mock at least once, but was never performed: v = v.Model = It.Is(value(Moq.It+<c__DisplayClass21[MoqTest.GenInfo]).match) at Moq.Mock.ThrowVerifyException(IProxyCall expected, Expression expression, Times times, Int32 callCount) at Moq.Mock.VerifyCalls(Interceptor targetInterceptor, MethodCall expected, Expression expression, Times times) at Moq.Mock.VerifySet[T](Mock1 mock, Action1 setterExpression, Times times, String failMessage) at Moq.Mock1.VerifySet(Action`1 setterExpression) Class1.cs(22,0): at MoqTest.TryClassTest.IsMessageNotNull() using System; using System.Collections.Generic; using System.Linq; using System.Text; using Moq; using NUnit.Framework; namespace MoqTest { [TestFixture] public class TryClassTest { [Test] public void IsMessageNotNull() { var mockView = new Mock<IView<GenInfo>>(); mockView.Setup(v => v.ModuleId).Returns(""); TryPresenter tryPresenter = new TryPresenter(mockView.Object); tryPresenter.SetMessage(new object(), new EventArgs()); // mockView.VerifySet(v => v.Message, Times.AtLeastOnce()); mockView.VerifySet(v => v.Model = It.Is<GenInfo>(x => x != null)); } } public class TryPresenter { private IView<GenInfo> view; public TryPresenter(IView<GenInfo> view) { this.view = view; } public void SetMessage(object sender, EventArgs e) { this.view.Model = null; } } public class MyView : IView<GenInfo> { #region Implementation of IView<GenInfo> public string ModuleId { get; set; } public GenInfo Model { get; set; } #endregion } public interface IView<T> { string ModuleId { get; set; } T Model { get; set; } } public class GenInfo { public String Message { get; set; } } } And if you change one line mockView.VerifySet(v => v.Model = It.Is<GenInfo>(x => x != null)); to mockView.VerifySet(v => v.Model, Times.AtLeastOnce()); it works fine. I think Exception is incorrect.

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  • Testing Django Inline ModelForms: How to arrange POST data?

    - by unclaimedbaggage
    Hi folks, I have a Django 'add business' view which adds a new business with an inline 'business_contact' form. The form works fine, but I'm wondering how to write up the unit test - specifically, the 'postdata' to send to self.client.post(settings.BUSINESS_ADD_URL, postdata) I've inspected the fields in my browser and tried adding post data with corresponding names, but I still get a 'ManagementForm data is missing or has been tampered with' error when run. Anyone know of any resources for figuring out how to post inline data? Relevant models, views & forms below if it helps. Lotsa thanks. MODEL: class Contact(models.Model): """ Contact details for the representatives of each business """ first_name = models.CharField(max_length=200) surname = models.CharField(max_length=200) business = models.ForeignKey('Business') slug = models.SlugField(max_length=150, unique=True, help_text=settings.SLUG_HELPER_TEXT) created = models.DateTimeField(auto_now_add=True) updated = models.DateTimeField(auto_now=True) phone = models.CharField(max_length=100, null=True, blank=True) mobile_phone = models.CharField(max_length=100, null=True, blank=True) email = models.EmailField(null=True) deleted = models.BooleanField(default=False) class Meta: db_table='business_contact' def __unicode__(self): return '%s %s' % (self.first_name, self.surname) @models.permalink def get_absolute_url(self): return('business_contact', (), {'contact_slug': self.slug }) class Business(models.Model): """ The business clients who you are selling products/services to """ business = models.CharField(max_length=255, unique=True) slug = models.SlugField(max_length=100, unique=True, help_text=settings.SLUG_HELPER_TEXT) description = models.TextField(null=True, blank=True) primary_contact = models.ForeignKey('Contact', null=True, blank=True, related_name='primary_contact') business_type = models.ForeignKey('BusinessType') deleted = models.BooleanField(default=False) created = models.DateTimeField(auto_now_add=True) updated = models.DateTimeField(auto_now=True) address_1 = models.CharField(max_length=255, null=True, blank=True) address_2 = models.CharField(max_length=255, null=True, blank=True) suburb = models.CharField(max_length=255, null=True, blank=True) city = models.CharField(max_length=255, null=True, blank=True) state = models.CharField(max_length=255, null=True, blank=True) country = models.CharField(max_length=255, null=True, blank=True) phone = models.CharField(max_length=40, null=True, blank=True) website = models.URLField(null=True, blank=True) class Meta: db_table = 'business' def __unicode__(self): return self.business def get_absolute_url(self): return '%s%s/' % (settings.BUSINESS_URL, self.slug) VIEWS: class Contact(models.Model): """ Contact details for the representatives of each business """ first_name = models.CharField(max_length=200) surname = models.CharField(max_length=200) business = models.ForeignKey('Business') slug = models.SlugField(max_length=150, unique=True, help_text=settings.SLUG_HELPER_TEXT) created = models.DateTimeField(auto_now_add=True) updated = models.DateTimeField(auto_now=True) phone = models.CharField(max_length=100, null=True, blank=True) mobile_phone = models.CharField(max_length=100, null=True, blank=True) email = models.EmailField(null=True) deleted = models.BooleanField(default=False) class Meta: db_table='business_contact' def __unicode__(self): return '%s %s' % (self.first_name, self.surname) @models.permalink def get_absolute_url(self): return('business_contact', (), {'contact_slug': self.slug }) class Business(models.Model): """ The business clients who you are selling products/services to """ business = models.CharField(max_length=255, unique=True) slug = models.SlugField(max_length=100, unique=True, help_text=settings.SLUG_HELPER_TEXT) description = models.TextField(null=True, blank=True) primary_contact = models.ForeignKey('Contact', null=True, blank=True, related_name='primary_contact') business_type = models.ForeignKey('BusinessType') deleted = models.BooleanField(default=False) created = models.DateTimeField(auto_now_add=True) updated = models.DateTimeField(auto_now=True) address_1 = models.CharField(max_length=255, null=True, blank=True) address_2 = models.CharField(max_length=255, null=True, blank=True) suburb = models.CharField(max_length=255, null=True, blank=True) city = models.CharField(max_length=255, null=True, blank=True) state = models.CharField(max_length=255, null=True, blank=True) country = models.CharField(max_length=255, null=True, blank=True) phone = models.CharField(max_length=40, null=True, blank=True) website = models.URLField(null=True, blank=True) class Meta: db_table = 'business' def __unicode__(self): return self.business def get_absolute_url(self): return '%s%s/' % (settings.BUSINESS_URL, self.slug) FORMS: class AddBusinessForm(ModelForm): class Meta: model = Business exclude = ['deleted','primary_contact',] class ContactForm(ModelForm): class Meta: model = Contact exclude = ['deleted',] AddBusinessFormSet = inlineformset_factory(Business, Contact, can_delete=False, extra=1, form=AddBusinessForm, )

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  • ASP.NET MVC ViewModel Pattern

    - by Omu
    EDIT: I made something much better to fill and read data from a view using ViewModels, called it ValueInjecter. http://valueinjecter.codeplex.com/documentation using the ViewModel to store the mapping logic was not such a good idea because there was repetition and SRP violation, but now with the ValueInjecter I have clean ViewModels and dry mapping code I made a ViewModel pattern for editing stuff in asp.net mvc this pattern is usefull when you have to make a form for editing an entity and you have to put on the form some dropdowns for the user to choose some values public class OrganisationViewModel { //paramterless constructor required, cuz we are gonna get an OrganisationViewModel object from the form in the post save method public OrganisationViewModel() : this(new Organisation()) {} public OrganisationViewModel(Organisation o) { Organisation = o; Country = new SelectList(LookupFacade.Country.GetAll(), "ID", "Description", CountryKey); } //that's the Type for whom i create the viewmodel public Organisation Organisation { get; set; } #region DropDowns //for each dropdown i have a int? Key that stores the selected value public IEnumerable<SelectListItem> Country { get; set; } public int? CountryKey { get { if (Organisation.Country != null) { return Organisation.Country.ID; } return null; } set { if (value.HasValue) { Organisation.Country = LookupFacade.Country.Get(value.Value); } } } #endregion } and that's how i use it public ViewResult Edit(int id) { var model = new OrganisationViewModel(organisationRepository.Get(id)); return View(model); } [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(OrganisationViewModel model) { organisationRepository.SaveOrUpdate(model.Organisation); return RedirectToAction("Index"); } and the markup <p> <label for="Name"> Name:</label> <%= Html.Hidden("Organisation.ID", Model.Organisation.ID)%> <%= Html.TextBox("Organisation.Name", Model.Organisation.Name)%> <%= Html.ValidationMessage("Organisation.Name", "*")%> </p> <p> ... <label for="CountryKey"> Country:</label> <%= Html.DropDownList("CountryKey", Model.Country, "please select") %> <%= Html.ValidationMessage("CountryKey", "*") %> </p> so tell me what you think about it

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  • Asynchronous callback for network in Objective-C Iphone

    - by vodkhang
    I am working with network request - response in Objective-C. There is something with asynchronous model that I don't understand. In summary, I have a view that will show my statuses from 2 social networks: Twitter and Facebook. When I clicked refresh, it will call a model manager. That model manager will call 2 service helpers to request for latest items. When 2 service helpers receive data, it will pass back to model manager and this model will add all data into a sorted array. What I don't understand here is that : when response from social networks come back, how many threads will handle the response. From my understanding about multithreading and networking (in Java), there must have 2 threads handle 2 responses and those 2 threads will execute the code to add the responses to the array. So, it can have race condition and the program can go wrong right? Is it the correct working model of iphone objective-C? Or they do it in a different way that it will never have race condition and we don't have to care about locking, synchronize? Here is my example code: ModelManager.m - (void)updateMyItems:(NSArray *)items { self.helpers = [self authenticatedHelpersForAction:NCHelperActionGetMyItems]; for (id<NCHelper> helper in self.helpers) { [helper updateMyItems:items]; // NETWORK request here } } - (void)helper:(id <NCHelper>)helper didReturnItems:(NSArray *)items { [self helperDidFinishGettingMyItems:items callback:@selector(model:didGetMyItems:)]; break; } } // some private attributes int *_currentSocialNetworkItemsCount = 0; // to count the number of items of a social network - (void)helperDidFinishGettingMyItems:(NSArray *)items { for (Item *item in items) { _currentSocialNetworkItemsCount ++; } NSLog(@"count: %d", _currentSocialNetworkItemsCount); _currentSocialNetworkItemsCount = 0; } I want to ask if there is a case that the method helperDidFinishGettingMyItems is called concurrently. That means, for example, faceboook returns 10 items, twitter returns 10 items, will the output of count will ever be larger than 10? And if there is only one single thread, how can the thread finishes parsing 1 response and jump to the other response because, IMO, thread is only executed sequently, block of code by block of code

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  • Keeping the DI-container usage in the composition root in Silverlight and MVVM

    - by adrian hara
    It's not quite clear to me how I can design so I keep the reference to the DI-container in the composition root for a Silverlight + MVVM application. I have the following simple usage scenario: there's a main view (perhaps a list of items) and an action to open an edit view for one single item. So the main view has to create and show the edit view when the user takes the action (e.g. clicks some button). For this I have the following code: public interface IView { IViewModel ViewModel {get; set;} } Then, for each view that I need to be able to create I have an abstract factory, like so public interface ISomeViewFactory { IView CreateView(); } This factory is then declared a dependency of the "parent" view model, like so: public class SomeParentViewModel { public SomeParentViewModel(ISomeViewFactory viewFactory) { // store it } private void OnSomeUserAction() { IView view = viewFactory.CreateView(); dialogService.ShowDialog(view); } } So all is well until here, no DI-container in sight :). Now comes the implementation of ISomeViewFactory: public class SomeViewFactory : ISomeViewFactory { public IView CreateView() { IView view = new SomeView(); view.ViewModel = ???? } } The "????" part is my problem, because the view model for the view needs to be resolved from the DI-container so it gets its dependencies injected. What I don't know is how I can do this without having a dependency to the DI-container anywhere except the composition root. One possible solution would be to have either a dependency on the view model that gets injected into the factory, like so: public class SomeViewFactory : ISomeViewFactory { public SomeViewFactory(ISomeViewModel viewModel) { // store it } public IView CreateView() { IView view = new SomeView(); view.ViewModel = viewModel; } } While this works, it has the problem that since the whole object graph is wired up "statically" (i.e. the "parent" view model will get an instance of SomeViewFactory, which will get an instance of SomeViewModel, and these will live as long as the "parent" view model lives), the injected view model implementation is stateful and if the user opens the child view twice, the second time the view model will be the same instance and have the state from before. I guess I could work around this with an "Initialize" method or something similar, but it doesn't smell quite right. Another solution might be to wrap the DI-container and have the factories depend on the wrapper, but it'd still be a DI-container "in disguise" there :) Any thoughts on this are greatly appreciated. Also, please forgive any mistakes or rule-breaking, since this is my first post on stackoverflow :) Thanks! ps: my current solution is that the factories know about the DI-container, and it's only them and the composition root that have this dependency.

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  • How can we implement change notification propagation for WPF and SL in the MVVM pattern?

    - by Firoso
    Here's an example scenario targetting MVVM WPF/SL development: View data binds to view model Property "Target" "Target" exposes a field of an object called "data" that exists in the local application model, called "Original" when "Original" changes, it should raise notification to the view model and then propogate that change notification to the View. Here are the solutions I've come up with, but I don't like any of them all that much. I'm looking for other ideas, by the time we come up with something rock solid I'm certain Microsoft will have released .NET 5 with WPF/SL extensions for better tools for MVVM development. For now the question is, "What have you done to solve this problem and how has it worked out for you?" Option 1. Proposal: Attach a handler to data's PropertyChanged event that watches for string values of properties it cares about that might have changed, and raises the appropriate notification. Why I don't like it: Changes don't bubble naturally, objects must be explicitly watched, if data changes to a new source, events must be un-registered/registered. Why I kind of like it: I get explicit control over propogation of changes, and I don't have to use any types that belong at a higher level of the application such as dependancy properties. Option 2. Proposal: Attach a handler to data's PropertyChanged event that re-raises the event across all properties using the name property name. Why I don't like it: This is essentially the same as option 1, but less intelligent, and forces me to never change my property names, as they have to be the same as the property names on data Why I kind of like it: It's very easy to set up and I don't have to think about it... Then again if I try to think, and change names to things that make sense, I shoot myself in the foot, and then I have to think about it! Option 3. Proposal: Inherit my view model from dependancy object, and notify binding sources of changes directly. Why I don't like it: I'm not even 100% sure dependancy properties/objects can DO this, it was just a thought to look into. Also I don't personally feel that WPF/SL types like Dep Obj belong at the view model level. Why I kind of like it: IF it has the capability that I'm seeking then it's a good answer! minus that pesky layering issue. Option 4. Proposal: Use a consistant agent messaging system based off of Task Parallels DataFlow Library to propogate everything through linked pipelining. Why I don't like it: I've never tried this, and somehow I think it will be lacking, plus it requires me to think about my code completely differently all the way around. Why I kind of like it: It has the possiblity of allowing me to do some VERY fun manipulations with a push based data model and using ActionBlocks as validation AND setters to then privately change view model properties and explicitly control PropertyChanged notifications.

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  • mutiple database in codeigniter

    - by adisembiring
    Hi ..., I'm trying to implement mutiple database in CI. My code Is here: //database.php $active_group = "default"; $active_record = TRUE; $db['default']['hostname'] = "localhost"; $db['default']['username'] = "root"; $db['default']['password'] = "root"; $db['default']['database'] = "ravelex"; $db['default']['dbdriver'] = "mysql"; $db['default']['dbprefix'] = "rvx_"; $db['default']['pconnect'] = TRUE; $db['default']['db_debug'] = TRUE; $db['default']['cache_on'] = FALSE; $db['default']['cachedir'] = ""; $db['default']['char_set'] = "utf8"; $db['default']['dbcollat'] = "utf8_general_ci"; $db['smf']['hostname'] = "localhost"; $db['smf']['username'] = "root"; $db['smf']['password'] = "root"; $db['smf']['database'] = "smf"; $db['smf']['dbdriver'] = "mysql"; $db['smf']['dbprefix'] = "smf_"; $db['smf']['pconnect'] = TRUE; $db['smf']['db_debug'] = TRUE; $db['smf']['cache_on'] = FALSE; $db['smf']['cachedir'] = ""; $db['smf']['char_set'] = "utf8"; $db['smf']['dbcollat'] = "utf8_general_ci"; The model is //user_model.php class user_model extends Model { private $ravelex_db; function user_model() { parent::Model(); $this->ravelex_db = $this->load->database('default', TRUE); } function find_all() { print_r($this->ravelex_db); $q = $this->ravelex_db->get('users'); return $q->result(); } } //smf_user_model.php class smf_user_model extends Model { private $smf_db; function smf_user_model() { parent::Model(); $this->smf_db = $this->load->database('smf', TRUE); } function find_all() { $q = $this->smf_db->get('members'); return $q->result(); } } Controller tester class mutipledb extends Controller { function mutipledb() { parent::Controller(); $this->load->database(); $this->load->model('user_model'); $this->load->model('smf_user_model'); } function index() { print_r($this->user_model->find_all()); print_r($this->smf_user_model->find_all()); } } There are some error, The first database uses the second database name. But it still use it's prefix. The error is A Database Error Occurred Error Number: 1146 Table 'smf.rvx_users' doesn't exist SELECT * FROM (`rvx_users`)

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  • Django FileField not saving to upload_to location

    - by Erik
    I have an Attachment model that has a FileField in a Django 1.4.1 app. This FileField has a callable upload_to parameter which, per the Django docs should be called when the form (and therefore the model) is saved. When I run FormTest below, the upload_to callable is never called and the file therefore does not appear in the location provided by the upload_to method. What am I doing wrong? Notice that in the passing tests in ModelTest (also below), the upload_to method works as expected. Test: from core.forms.attachments import AttachmentForm from django.test import TestCase import unittest from django.core.files.uploadedfile import SimpleUploadedFile from django.core.files.storage import default_storage def suite(): return unittest.TestSuite( [ unittest.TestLoader().loadTestsFromTestCase(FormTest), ] ) class FormTest(TestCase): def test_form_1(self): filename = 'filename' f = file(filename) data = {'name':'name',} file_data = {'attachment_file':SimpleUploadedFile(f.name,f.read()),} form = AttachmentForm(data=data,files=file_data) self.assertTrue(form.is_valid()) attachment = form.save() root_directory = 'attachments' upload_location = root_directory + '/' + attachment.directory + '/' + filename self.assertTrue(attachment.attachment_file) # Fails self.assertTrue(default_storage.exists(upload_location)) # Fails Attachment Model: from django.db import models from parent_mixins import Parent_Mixin import uuid from django.db.models.signals import pre_delete,pre_save from dirtyfields import DirtyFieldsMixin def upload_to(instance,filename): return 'attachments/' + instance.directory + '/' + filename def uuid_directory_name(): return uuid.uuid4().hex class Attachment(DirtyFieldsMixin,Parent_Mixin,models.Model): attachment_file = models.FileField(blank=True,null=True,upload_to=upload_to) directory = models.CharField(blank=False,default=uuid_directory_name,null=False,max_length=32) name = models.CharField(blank=False,default=None,null=False,max_length=128) class Meta: app_label = 'core' def __str__(self): return unicode(self).encode('utf-8') def __unicode__(self): return unicode(self.name) @models.permalink def get_absolute_url(self): return('core_attachments_update',(),{'pk': self.pk}) # def save(self,*args,**kwargs): # super(Attachment,self).save(*args,**kwargs) def pre_delete_callback(sender, instance, *args, **kwargs): if not isinstance(instance, Attachment): return if not instance.attachment_file: return instance.attachment_file.delete(save=False) def pre_save_callback(sender, instance, *args, **kwargs): if not isinstance(instance, Attachment): return if not instance.attachment_file: return if instance.is_dirty(): dirty_fields = instance.get_dirty_fields() if 'attachment_file' in dirty_fields: old_attachment_file = dirty_fields['attachment_file'] old_attachment_file.delete() pre_delete.connect(pre_delete_callback) pre_save.connect(pre_save_callback) Attachment Form: from ..models.attachments import Attachment from crispy_forms.helper import FormHelper from crispy_forms.layout import Div,Layout,HTML,Field,Fieldset,Button,ButtonHolder,Submit from django import forms class AttachmentFormHelper(FormHelper): form_tag=False layout = Layout( Div( Div( Field('name',css_class='span4'), Field('attachment_file',css_class='span4'), css_class='span4', ), css_class='row', ), ) class AttachmentForm(forms.ModelForm): helper = AttachmentFormHelper() class Meta: fields=('attachment_file','name') model = Attachment class AttachmentInlineFormHelper(FormHelper): form_tag=False form_style='inline' layout = Layout( Div( Div( Field('name',css_class='span4'), Field('attachment_file',css_class='span4'), Field('DELETE',css_class='span4'), css_class='span4', ), css_class='row', ), ) class AttachmentInlineForm(forms.ModelForm): helper = AttachmentInlineFormHelper() class Meta: fields=('attachment_file','name') model = Attachment UPDATE I also do testing on the Attachment model class with these unit tests -- which all pass: from core.models.attachments import Attachment from core.models.attachments import upload_to from django.test import TestCase import unittest from django.core.files.storage import default_storage from django.core.files.base import ContentFile def suite(): return unittest.TestSuite( [ unittest.TestLoader().loadTestsFromTestCase(ModelTest), ] ) class ModelTest(TestCase): def test_model_minimum_fields(self): attachment = Attachment(name='name') attachment.attachment_file.save('test.txt',ContentFile("hello world")) attachment.save() self.assertEqual(str(attachment),'name') self.assertEqual(unicode(attachment),'name') self.assertTrue(attachment.directory) # def test_model_full_fields(self): # attachment = Attachment() # attachement.save() def test_file_operations_basic(self): root_directory = 'attachments' filename = 'test.txt' attachment = Attachment(name='name') attachment.attachment_file.save(filename,ContentFile('test')) attachment.save() upload_location = root_directory + '/' + attachment.directory + '/' + filename self.assertEqual(upload_to(attachment,filename),upload_location) self.assertTrue(default_storage.exists(upload_location)) def test_file_operations_delete(self): root_directory = 'attachments' filename = 'test.txt' attachment = Attachment(name='name') attachment.attachment_file.save(filename,ContentFile('test')) attachment.save() upload_location = upload_to(attachment,filename) attachment.delete() self.assertFalse(default_storage.exists(upload_location)) def test_file_operations_change(self): root_directory = 'attachments' filename_1 = 'test_1.txt' attachment = Attachment(name='name') attachment.attachment_file.save(filename_1,ContentFile('test')) attachment.save() upload_location_1 = upload_to(attachment,filename_1) self.assertTrue(default_storage.exists(upload_location_1)) filename_2 = 'test_2.txt' attachment.attachment_file.save(filename_2,ContentFile('test')) attachment.save() upload_location_2 = upload_to(attachment,filename_2) self.assertTrue(default_storage.exists(upload_location_2)) self.assertFalse(default_storage.exists(upload_location_1))

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  • How to best integrate generated code

    - by Arne
    I am evaluating the use of code generation for my flight simulation project. More specifically there is a requirement to allow "the average engineer" (no offense I am one myself) to define the differential equations that describe the dynamic system in a more natural syntax than C++ provides. The idea is to devise a abstract descriptor language that can be easily understood and edited to generate C++ code from. This descriptor is supplied by the modeling engineer and used by the ones implementing and maintaining the simulation evironment to generate code. I've got something like this in mind: model Aircraft has state x1, x2; state x3; input double : u; input bool : flag1, flag2; algebraic double : x1x2; model Engine : tw1, tw2; model Gear : gear; model ISA : isa; trim routine HorizontalFight; trim routine OnGround, General; constant double : c1, c2; constant int : ci1; begin differential equations x1' = x1 + 2.*x2; x2' = x2 + x1x2; begin algebraic equations x1x2 = x1*x2 + x1'; end model It is important to retain the flexibility of the C language thus the descriptor language is meant to only define certain parts of the definition and implementation of the model class. This way one enigneer provides the model in from of the descriptor language as examplified above and the maintenance enigneer will add all the code to read parameters from files, start/stop/pause the execution of the simulation and how a concrete object gets instatiated. My first though is to either generate two files from the descriptor file: one .h file containing declarations and one .cpp file containing the implementation of certain functions. These then need to be #included at appropriate places [File Aircarft.h] class Aircraft { public: void Aircraft(..); // hand-written constructor void ReadParameters(string &file_name); // hand-written private: /* more hand wirtten boiler-plate code */ /* generate declarations follow */ #include "Aircraft.generated.decl" }; [File Aircraft.cpp] Aircarft::Aircraft(..) { /* hand-written constructer implementation */ } /* more hand-written implementation code */ /* generated implementation code follows */ #include "Aircraft.generated.impl" Any thoughts or suggestions?

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  • ASP.NET MVC null ViewResult

    - by David Neale
    How should one deal with an MVC controller returning a null ViewResult? As an example I am creating a simple edit view: public ActionResult Edit(int id) { var person = (from p in context.SWLiftShare_Persons where p.id == id select p).SingleOrDefault(); if (person != null) { return View(person); } else return View(); } I guess in reality there's no point in checking for a null result in the controller because the view picks out properties from the model: <h2>Edit - <%= Html.Encode(Model.Name) %></h2> <%= Html.ValidationSummary("Edit was unsuccessful. Please correct the errors and try again.") %> <% using (Html.BeginForm()) {%> <fieldset> <legend>Fields</legend> <p> <label for="id">id: <%= Html.Encode(Model.id) %></label> </p> <p> <label for="CollarNumber">CollarNumber:</label> <%= Html.TextBox("CollarNumber", Model.CollarNumber)%> <%= Html.ValidationMessage("CollarNumber", "*") %> </p> <p> <label for="Name">Name:</label> <%= Html.TextBox("Name", Model.Name)%> <%= Html.ValidationMessage("Name", "*") %> </p> <p> <label for="EmailAddress">EmailAddress:</label> <%= Html.TextBox("EmailAddress", Model.EmailAddress, new { style = "width:300px" })%> <%= Html.ValidationMessage("EmailAddress", "*") %> </p> <p> <input type="submit" value="Save" /> </p> </fieldset> <% } %> I could just wrap everything in a <% if(Model != null) { //render edit markup... etc. but that seems rather unelegant. Is there a better way to deal with this?

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