You can check whether or not the ModelState is valid, but keep in mind that you&#39;re only checking the validity of the ModelState at the time the web request was made:

    @if (ViewData.ModelState.IsValid) {
        ...
    }


Additionally, you can check validatity of a property on the model in the view: 

    @if (ViewData.ModelState.IsValidField(&quot;FIELD_NAME&quot;)) {
        ...
    }

&gt; **Possible Duplicate:**  
&gt; [Javascript === vs == : Does it matter which &amp;ldquo;equal&amp;rdquo; operator I use?](https://stackoverflow.com/questions/359494/javascript-vs-does-it-matter-which-equal-operator-i-use)  
&gt; [Difference between == and === in JavaScript](https://stackoverflow.com/questions/523643/difference-between-and-in-javascript)  

&lt;!-- End of automatically inserted text --&gt;

I have two variables to compare.

Result should not be equal, in which condition i need to use !=  and  !== ?

because when i use both operator it is working properly, but i need to know exactly what is the difference. 



Javascript Comparison Operators != vs !==

I am very confused about those two terms. Are they the same or different?

Some books and people say they are the same and others say they are different.

I tried but couldn&#39;t find a conclusive answer.


What is difference between foreign key and reference key?

I need to do a check if my model is valid from inside my Razor view. If it&#39;s valid then I want to be able to show some HTML. 

How can I do this. I want something like 

    @if ( Model.IsValid ) {
    
    }

but the above does not work

How can I check if my model is valid from inside the razor view?

I need to do a check if my model is valid from inside my Razor view. If it's valid then I want to be able to show some HTML.
How can I do this. I want something like
<pre><code class="hljs language-less">@if ( Model.IsValid ) {

}
</code></pre>
but the above does not work

I have been developing enterprise applications for many years using .Net 
My apps usually have a domain model containing entities mapping to SQL DB tables.
I use a Repository pattern, Dependency injection and a service layer.

Recently we started working on MVC 3 projects and we had a debate where to put which logic.
I came accross thin Controller / FAT Model architecture and was wondering how the service layer would fit in

## Option 1 - Model talks to services ##
Controller is thin, calls methods on the models. The models &quot;know&quot; how to load themselfs from the DB and talk to repositories or services.
E.g. customerModel has a Load(id) method and loads the customer and some child objects like GetContracts().

## Option 2 - Controller talks to services ##

Controller asks Services to retrieve model objects. The logic of loading / storing etc. Is in the service layer. The model is a pure entity model with data only.

Why would option 1 be a better choice especially when we talk about enterprise applictions my experience tells me to separate concerns, keep models AND Controllers as thin as possible and have specialized services doing the Business logic (imcl. The DB interaction)

Thanks for all advices and references to good resources.


Fat model / thin controller vs. Service layer

&gt; After this question, it makes me comfortable when using async
&gt; operations in ASP.NET MVC. So, I wrote two blog posts on that:
&gt; 
&gt;  - [My Take on Task-based Asynchronous Programming in C# 5.0 and ASP.NET    MVC Web Applications][2]
&gt;  - [Asynchronous Database Calls With Task-based Asynchronous Programming    Model (TAP) in ASP.NET MVC 4][1]

I have too many misunderstandings in my mind about asynchronous operations on ASP.NET MVC.

I always hear this sentence: ***Application can scale better if operations run asynchronously***

And I heard this kind of sentences a lot as well: ***if you have a huge volume of traffic, you may be better off not performing your queries asynchronously - consuming 2 extra threads to service one request takes resources away from other incoming requests.***

I think those two sentences are inconsistent. 

I do not have much information about how threadpool works on ASP.NET but I know that threadpool has a limited size for threads. So, the second sentence has to be related to this issue.

And I would like to know if asynchronous operations in ASP.NET MVC uses a thread from ThreadPool on .NET 4? 

For example, when we implement a AsyncController, how does the app structures? If I get huge traffic, is it a good idea to implement AsyncController?

Is there anybody out there who can take this black curtain away in front of my eyes and explain me the deal about asynchrony on ASP.NET MVC 3 (NET 4)?

**Edit:**

I have read this below document nearly hundreds of times and I understand the main deal but still I have confusion because there are too much inconsistent comment out there.

[Using an Asynchronous Controller in ASP.NET MVC][3]

**Edit:**

Let&#39;s assume I have controller action like below (not an implementation of `AsyncController` though):

    public ViewResult Index() { 
        
        Task.Factory.StartNew(() =&gt; { 
            //Do an advanced looging here which takes a while
        });
        
        return View();
    }

As you see here, I fire an operation and forget about it. Then, I return immediately without waiting it be completed. 

In this case, does this have to use a thread from threadpool? If so, after it completes, what happens to that thread? Does `GC` comes in and clean up just after it completes?

**Edit:**

For the @Darin&#39;s answer, here is a sample of async code which talks to database:

    public class FooController : AsyncController {
    
        //EF 4.2 DbContext instance
        MyContext _context = new MyContext();
    
        public void IndexAsync() { 
            
            AsyncManager.OutstandingOperations.Increment(3);
            
            Task&lt;IEnumerable&lt;Foo&gt;&gt;.Factory.StartNew(() =&gt; { 
            
               return 
                    _context.Foos;
            }).ContinueWith(t =&gt; {
            
                AsyncManager.Parameters[&quot;foos&quot;] = t.Result;
                AsyncManager.OutstandingOperations.Decrement();
            });
            
            Task&lt;IEnumerable&lt;Bars&gt;&gt;.Factory.StartNew(() =&gt; { 
            
               return 
                    _context.Bars;
            }).ContinueWith(t =&gt; {
            
                AsyncManager.Parameters[&quot;bars&quot;] = t.Result;
                AsyncManager.OutstandingOperations.Decrement();
            });
            
            Task&lt;IEnumerable&lt;FooBar&gt;&gt;.Factory.StartNew(() =&gt; { 
            
               return 
                    _context.FooBars;
            }).ContinueWith(t =&gt; {
            
                AsyncManager.Parameters[&quot;foobars&quot;] = t.Result;
                AsyncManager.OutstandingOperations.Decrement();
            });
        }
        
        public ViewResult IndexCompleted(
            IEnumerable&lt;Foo&gt; foos, 
            IEnumerable&lt;Bar&gt; bars,
            IEnumerable&lt;FooBar&gt; foobars) {
            
            //Do the regular stuff and return
            
        }
    }


  [1]: http://www.tugberkugurlu.com/archive/asynchronous-database-calls-with-task-based-asynchronous-programming-model-tap-in-asp-net-mvc-4
  [2]: http://www.tugberkugurlu.com/archive/my-take-on-task-base-asynchronous-programming-in-c-sharp-5-0-and-asp-net-mvc-web-applications
  [3]: http://msdn.microsoft.com/en-us/library/ee728598.aspx

Do asynchronous operations in ASP.NET MVC use a thread from ThreadPool on .NET 4

In a .NET MVC 3.0 Application I have the following configuration in `appSettings`:

&lt;h1&gt;web.config&lt;/h1&gt;

    &lt;appSettings&gt;
    &lt;add key=&quot;SMTPHost&quot; value=&quot;mail.domain.com&quot;/&gt;
        &lt;add key=&quot;SMTPUsername&quot; value=&quot;user@gmail.com&quot;/&gt;
        &lt;add key=&quot;SMTPPort&quot; value=&quot;25&quot;/&gt;
        &lt;add key=&quot;SMTPPwd&quot; value=&quot;mypassword&quot;/&gt;
        &lt;add key=&quot;EmailFrom&quot; value=&quot;notific@gmail.com&quot;/&gt;
    &lt;/appSettings&gt;

For debugging, I have the following configuration transform defined:

&lt;h1&gt;web.Debug.config&lt;/h1&gt;

    &lt;appSettings&gt;
        &lt;add  key=&quot;SMTPPort&quot; value=&quot;58&quot; xdt:Transform=&quot;Replace&quot; xdt:Locator=&quot;Match(key)&quot; /&gt;
    &lt;/appSettings&gt;

And I run the application in debug mode, but my SMTP port is still taking the value from the `web.config`, not `web.Debug.config`.

Can anyone suggest what could be wrong in this configuration?

Web Config Transform not working

What steps should I take to safely upgrade an existing ASP.NET MVC 3 project to the latest ASP.NET MVC 4 [Developer Preview][1]?

  [1]: http://www.asp.net/mvc/mvc4

Converting a ASP.NET MVC 3 Project to MVC 4

I have sample code like this:
    
     &lt;div class=&quot;cart&quot;&gt;
          &lt;a onclick=&quot;addToCart(&#39;@Model.productId&#39;);&quot; class=&quot;button&quot;&gt;&lt;span&gt;Add to Cart&lt;/span&gt;&lt;/a&gt;
     &lt;/div&gt;
     &lt;div class=&quot;wishlist&quot;&gt;
          &lt;a onclick=&quot;addToWishList(&#39;@Model.productId&#39;);&quot;&gt;Add to Wish List&lt;/a&gt;
     &lt;/div&gt;
     &lt;div class=&quot;compare&quot;&gt;
          &lt;a onclick=&quot;addToCompare(&#39;@Model.productId&#39;);&quot;&gt;Add to Compare&lt;/a&gt;
     &lt;/div&gt;    
    
How can I write JavaScript code to call the controller action method?
   


Calling ASP.NET MVC Action Methods from JavaScript

I&#39;m  using a jQuery modal dialog in my ASP .NET MVC 3 application. It works fine except for that there is no close button showing in the top right corner. How can I add this?

    $(&quot;#dialog-modal&quot;).dialog({
                modal: true,
                autoOpen: false,
                buttons: {
                    Ok: function () {
                        $(this).dialog(&quot;close&quot;);
                    }
                }
            });

jQueryUI modal dialog does not show close button (x)

How do I create a readonly textbox in ASP.NET MVC3 with the Razor view engine?

Is there an HTMLHelper method available to do that?

Something like the following?

    @Html.ReadOnlyTextBoxFor(m =&gt; m.userCode)





How to create a readonly textbox in ASP.NET MVC3 Razor

Are `MicrosoftAjax.js`, `MicrosoftMvcAjax.js` and `MicrosoftMvcValidation.js` obsolete as of ASP.NET MVC 3? I haven&#39;t been able to find much info on this on the web, but from what I&#39;ve read it implies that these files were used in ASP.NET MVC 1-2, and were replaced by `jquery.validate.min.js`, `jquery.unobtrusive-ajax.min.js` and `jquery.validate.unobtrusive.min.js`. Is that correct? Do I still need the Microsoft files?

Are MicrosoftAjax.js, MicrosoftMvcAjax.js and MicrosoftMvcValidation.js obsolete as of ASP.NET MVC 3?

Imagine a common scenario, this is a simpler version of what I&#39;m coming across.  I actually have a couple of layers of further nesting on mine....

But this is the scenario

Theme contains List&lt;Category&gt;
Category contains List&lt;Product&gt;
Product contains List&lt;Order&gt;

My Controller provides a fully populated Theme, with all the Categories for that theme, the Products within this categories and the their orders.

The orders collection has a property called Quantity (amongst many others) that needs to be editable.

    @model ViewModels.MyViewModels.Theme
    
    @Html.LabelFor(Model.Theme.name)
    @foreach (var category in Model.Theme)
    {
       @Html.LabelFor(category.name)
       @foreach(var product in theme.Products)
       {
          @Html.LabelFor(product.name)
          @foreach(var order in product.Orders)
          {
              @Html.TextBoxFor(order.Quantity)
              @Html.TextAreaFor(order.Note)
              @Html.EditorFor(order.DateRequestedDeliveryFor)
          }
       }
    }

If I use lambda instead then then I only seem to get a reference to the top Model object, &quot;Theme&quot; not those within the foreach loop.


Is what I&#39;m trying to do there even possible or have I overestimated or misunderstood what is possible?

With the above I get an error on the TextboxFor, EditorFor, etc

&gt; CS0411: The type arguments for method
&gt; &#39;System.Web.Mvc.Html.InputExtensions.TextBoxFor&lt;TModel,TProperty&gt;(System.Web.Mvc.HtmlHelper&lt;TModel&gt;,
&gt; System.Linq.Expressions.Expression&lt;System.Func&lt;TModel,TProperty&gt;&gt;)&#39;
&gt; cannot be inferred from the usage. Try specifying the type arguments
&gt; explicitly.

Thanks.

MVC Razor view nested foreach&#39;s model

Embarrassingly newbie question:

I have a `string` field in my model that contains line breaks.  

    @Html.DisplayFor(x =&gt; x.MultiLineText)

does not display the line breaks.

Obviously I could do some fiddling in the model and create another field that replaces `\n` with `&lt;br/&gt;`, but that seems kludgy.  What&#39;s the textbook way to make this work?

How to make Html.DisplayFor display line breaks?

I am completely new to ASP.Net MVC. I just created an MVC3 project in Visual Studio 2010. The view engine is razor.  When I just ran the application it gave the proper result in the browser. The URL is http://localhost:4163/ . Then I applied “Set as Start Page” to Index.cshtml inside ~\Views\Home folder. Then when I ran the application the url became  http://localhost:4148/Views/Home/Index.cshtml  and it said the resource cannot be found.  What do I do to correct it? Where is the url mapping done?


Global.asax file:

    using System.Web.Mvc;
    using System.Web.Routing;

    namespace TEST
    {

    public class MvcApplication : System.Web.HttpApplication
    {
        public static void RegisterGlobalFilters(GlobalFilterCollection filters)
        {
            filters.Add(new HandleErrorAttribute());
        }

        public static void RegisterRoutes(RouteCollection routes)
        {
            routes.IgnoreRoute(&quot;{resource}.axd/{*pathInfo}&quot;);

            routes.MapRoute(
                &quot;Default&quot;, // Route name
                &quot;{controller}/{action}/{id}&quot;, // URL with parameters
                new { controller = &quot;Home&quot;, action = &quot;Index&quot;, id = UrlParameter.Optional } // Parameter defaults
            );

        }

        protected void Application_Start()
        {
            AreaRegistration.RegisterAllAreas();

            RegisterGlobalFilters(GlobalFilters.Filters);
            RegisterRoutes(RouteTable.Routes);
        }
        }
     }

Content Type	Original Author	Original Content on Stackoverflow
Question	Samantha J T Star	View Question on Stackoverflow
Solution 1 - asp.net Mvc	Phil Klein	View Answer on Stackoverflow

How can I check if my model is valid from inside the razor view?

asp.net Mvc Problem Overview

asp.net Mvc Solutions

Solution 1 - asp.net Mvc

What is difference between foreign key and reference key?

Javascript Comparison Operators != vs !==

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