Jack @ ASP.NET

The final release of VS 2010 and Visual Web Developer 2010 will have ASP.NET MVC 2 built-in – so you won’t need an additional install in order to use ASP.NET MVC 2 with them.

ASP.NET MVC 2 Features

• New Strongly Typed HTML Helpers
• Enhanced Model Validation support across both server and client
• Auto-Scaffold UI Helpers with Template Customization
• Support for splitting up large applications into “Areas”
• Asynchronous Controllers support that enables long running tasks in parallel
• Support for rendering sub-sections of a page/site using Html.RenderAction
• Lots of new helper functions, utilities, and API enhancements
• Improved Visual Studio tooling support

ASP.NET MVC 2 is the next significant update of ASP.NET MVC. It is a compatible update to ASP.NET MVC 1 – so all the knowledge, skills, code, and extensions you already have with ASP.NET MVC continue to work and apply going forward.

ASP.NET MVC 2 is the next significant update of ASP.NET MVC. It is a compatible update to ASP.NET MVC 1 – so all the knowledge, skills, code, and extensions you already have with ASP.NET MVC continue to work and apply going forward. Like the first release, we are also shipping the source code for ASP.NET MVC 2 under an OSI-compliant open-source license.

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. Download it at: http://www.microsoft.com/downloads/details.aspx?FamilyID=7aba081a-19b9-44c4-a247-3882c8f749e3&displaylang=en

What is new:

• 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).

Unfortunately, because Visual Studio 2010 Beta 2 and ASP.NET MVC 2 Beta share components which are currently not in sync, running ASP.NET MVC 2 Beta on VS10 Beta 2 is not supported. Regarding Visual Studio 2010 and .NET 4 support, that is unfortunately not a feasible option. The most recent public release of VS2010 and .NET 4 is Beta 2. However, our internal builds of MVC 2 for VS2010 and .NET 4 depend on features that were available only after Beta 2. In other words, if we released what we have right now for VS2010 and .NET 4 then it wouldn’t even run.

The good news is that the Visual Studio 2010 Release Candidate will include a newer version of ASP.NET MVC 2. 

Highlights

As you might expect from a release candidate, most of the work focused on bug fixes and improvements to existing features. We also spent a lot of time on performance profiling and optimization.

Much of the focus on this release was in the client validation scripts. For example, the validation script was moved into its own file and can be included at the top or bottom of the page. Client validation also now supports globalization.

The other change related to validation is that the ValidationSummary now supports overloads where only model-level errors are displayed. This is useful if you are displaying validation messages inline next to each form field. Previously, these messages would be duplicated in the validation summary. With these new changes, you can have the summary display an overall validation message (ex. “There were errors in your form submission”) as well as a list of validation messages which don’t apply to a specific field.

What’s Next?

RTM of course! The RTM release of ASP.NET MVC will be included in the RTM release of Visual Studio 2010, which is slated for some time in March. The VS2008 version of ASP.NET MVC 2 might release earlier than that. We’re still working out those details.