The ASP.NET team shipped ASP.NET MVC 2 Release Candidate 2 for VS 2008/.NET 3.5, and it’s the sequel to the RC version made available in December. It features bug fixes, performance optimizations, and API and behavior additions/changes.  Below are a few of the changes between the RC1 and RC2 release (read the release notes for even more details):

• The new ASP.NET MVC 2 validation feature now performs model-validation instead of input-validation (this means that when you use model binding all model properties are validated instead of just validations on changed values of a model).  This behavior change was based on extensive feedback from the community.

• The new strongly-typed HTML input helpers now support lambda expressions which reference array or collection indexes.  This means you can now write code like Html.EditorFor(m=>m.Orders[i]) and have it correctly output an HTML input element whose “name” attribute contains the index (e.g. Orders[0] for the first element), and whose “value” contains the appropriate value.

• The new templated Html.EditorFor() and Html.DisplayFor() helper methods now auto-scaffold simple properties (and do not render complex sub-properties by default).  This makes it easier to generate automatic scaffolded forms.  I’ll be covering this support in a future blog post.

• The “id” attribute of client-script validation message elements is now cleaner.  With RC1 they had a form0_ prefix.  Now the id value is simply the input form element name postfixed with a validationMessage string (e.g. unitPrice_validationMessage).

• The Html.ValidationSummary() helper method now takes an optional boolean parameter which enables you to control whether only model-level validation messages are rendered by it, or whether property level validation messages are rendered as well.  This provides you with more UI customization options for how validation messages are displayed within your UI.

• The AccountController class created with the default ASP.NET MVC Web Application project template is cleaner.

• Visual Studio now includes scaffolding support for Delete action methods within Controllers, as well as Delete views (I always found it odd that the default T4 templates didn’t support this before).

• jQuery 1.4.1 is now included by default with new ASP.NET MVC 2 projects, along with a –vsdoc file that provides Visual Studio documentation intellisense for it.

• The RC2 release has some significant performance tuning improvements (for example: the lambda based strongly-typed HTML helpers are now much faster).

Today’s RC2 release only work with VS 2008 and .NET 3.5.  We’ll shortly be releasing the VS 2010 RC (which will be available for everyone to download). It will include ASP. NET MVC 2 support built-in (no separate download required).

You can download it here.

Source: ScottGu

One of the first novelties straight from PDC 2009 is the release of ASP.NET MVC 2 Beta for Visual Studio 2008. You can download ASP.NET MVC 2 Beta from Microsoft Downloads here.

 For the newcomers, here’s a quick description of the technology:

“ASP.NET MVC 2 is a framework for developing highly testable and maintainable Web applications by leveraging the Model-View-Controller (MVC) pattern. The framework encourages developers to maintain a clear separation of concerns among the responsibilities of the application – the UI logic using the view, user-input handling using the controller, and the domain logic using the model. ASP.NET MVC applications are easily testable using techniques such as test-driven development (TDD).

 The installation package includes templates and tools for Visual Studio 2008 SP 1 to increase productivity when writing ASP.NET MVC applications. For example, the Add View dialog box takes advantage of customizable code generation (T4) templates to generate a view based on a model object. The default project template allows the developer to automatically hook up a unit-test project that is associated with the ASP.NET MVC application. Because the ASP.NET MVC framework is built on ASP.NET 3.5 SP 1, developers can take advantage of existing ASP.NET features like authentication and authorization, profile settings, localization, and so on.”

 New features in this release include:

 New RenderAction Method

Html.RenderAction (and its counterpart Html.Action) is an HTML helper method that calls into an action method from within a view and renders the output of the action method in place. Html.RenderAction writes directly to the response, whereas Html.Action returns a string with the output. RenderAction works only with actions that render views.

Strongly Typed UI Helpers

ASP.NET MVC 2 includes new expression-based versions of existing HTML helper methods. The new helpers include the following:

• ValidationMessageFor
• TextAreaFor
• TextBoxFor
• HiddenFor
• DropDownListFor

 TempDataDictionary Improvements

The behavior of the TempDataDictionary class has been changed slightly to address scenarios where temp data was either removed prematurely or persisted longer than necessary. For example, in cases where temp data was read in the same request in which it was set, the temp data was persisting for the next request even though the intent was to remove it. In other cases, temp data was not persisted across multiple consecutive redirects.

 Client Validation Library

MicrosoftMvcAjax.js now includes a client-side validation library that is used to provide client validation for models in ASP.NET MVC.

 “Add Area” Dialog Box

ASP.NET MVC 2 Beta includes a new Add Area context menu item when you right-click either the root project node or the Areas folder (if one exists). If a root Areas folder does not already exist, the command creates one, and it then creates the files and folders for the area that you specify.

 Calling Action Methods Asynchronously

The AsyncController class is a base class for controllers that enables action methods to be called asynchronously. This lets an action method call external services such as a Web service without blocking the current thread. For more information, see Using an Asynchronous Controller in ASP.NET MVC In the ASP.NET MVC 2 documentation.

 Blank Project Template

In response to customer feedback, an empty ASP.NET MVC project template is now included with ASP.NET MVC 2 Beta. This empty project template contains a minimal set of files used to build a new ASP.NET MVC project.

 Multiple Model Validator Providers

ASP.NET MVC 2 Beta lets you register multiple validation providers.

Multiple Value Provider Registration

In ASP.NET MVC 2 Beta, the single value provider that was available in ASP.NET MVC 1.0 has been split into multiple value providers, one for each source of request data. The new value providers include the following:

• FormValueProvider
• RouteDataValueProvider
• QueryStringValueProvider
• HttpFileCollectionValueProvider

These value providers are registered by default. You can register additional value providers that pull data from other sources.

 Download Microsoft ASP.NET MVC 2 Beta here (2.2 Mb).

ASP.NET MVC 2.0 Preview 2 has been released today and you can now count on:

• Client-Side Validation – ASP.NET MVC 2 includes the jQuery validation library to provide client-side validation based on the model’s validation metadata. It is possible to hook in alternative client-side validation libraries by writing an adapter which adapts the client library to the JSON metadata in a manner similar to the xVal validation framework.
• Areas – Preview 2 includes in-the-box support for single project areas for developers who wish to organize their application without requiring multiple projects. Registration of areas has also been streamlined.
• Model Validation Providers – allow hooking in alternative validation logic to provide validation when model binding. The default validation providers uses Data Annotations.
• Metadata Providers – allow hooking in alternative sources of metadata for model objects. The default metadata provider uses Data Annotations.”

Download ASP.NET MVC 2.0 Preview 2 here.