Wednesday, July 28, 2010

Introducing “Razor” – a new view engine for ASP.NET

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One of the things my team has been working on has been a new view engine option for ASP.NET.

ASP.NET MVC has always supported the concept of “view engines” – which are the pluggable modules that implement different template syntax options.  The “default” view engine for ASP.NET MVC today uses the same .aspx/.ascx/.master file templates as ASP.NET Web Forms.  Other popular ASP.NET MVC view engines used today include Spark and NHaml.

The new view-engine option we’ve been working on is optimized around HTML generation using a code-focused templating approach. The codename for this new view engine is “Razor”, and we’ll be shipping the first public beta of it shortly.

Design Goals

We had several design goals in mind as we prototyped and evaluated “Razor”:

Compact, Expressive, and Fluid: Razor minimizes the number of characters and keystrokes required in a file, and enables a fast, fluid coding workflow. Unlike most template syntaxes, you do not need to interrupt your coding to explicitly denote server blocks within your HTML. The parser is smart enough to infer this from your code. This enables a really compact and expressive syntax which is clean, fast and fun to type.

Easy to Learn: Razor is easy to learn and enables you to quickly be productive with a minimum of concepts. You use all your existing language and HTML skills.

Is not a new language: We consciously chose not to create a new imperative language with Razor. Instead we wanted to enable developers to use their existing C#/VB (or other) language skills with Razor, and deliver a template markup syntax that enables an awesome HTML construction workflow with your language of choice.

Works with any Text Editor: Razor doesn’t require a specific tool and enables you to be productive in any plain old text editor (notepad works great).

Has great Intellisense: While Razor has been designed to not require a specific tool or code editor, it will have awesome statement completion support within Visual Studio. We’ll be updating Visual Studio 2010 and Visual Web Developer 2010 to have full editor intellisense for it.

Unit Testable: The new view engine implementation will support the ability to unit test views (without requiring a controller or web-server, and can be hosted in any unit test project – no special app-domain required).

We’ve spent the last few months building applications with it and doing lots of usability studies of it with a variety of volunteers (including several groups of non-.NET web developers). The feedback so far from people using it has been really great.

Choice and Flexibility

One of the best things about ASP.NET is that most things in it are pluggable. If you find something doesn’t work the way you want it to, you can swap it out for something else.

The next release of ASP.NET MVC will include a new “Add->View” dialog that makes it easy for you to choose the syntax you want to use when you create a new view template file.  It will allow you to easily select any of of the available view engines you have installed on your machine – giving you the choice to use whichever view approach feels most natural to you

Read more: ScottGu's Blog

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