C# Razor Syntax Quick Reference

转自：http://haacked.com/archive/2011/01/06/razor-syntax-quick-reference.aspx/

I gave a presentation to another team at  Microsoft  yesterday on ASP.NET MVC and the Razor view engine and someone asked if there was a reference for the Razor syntax.

It turns out, there is a pretty good guide about Razor available, but it’s focused on covering the basics of  web programming  using Razor and inline pages and not just the Razor syntax.

So I thought it might be handy to write up a a really concise quick reference about the Razor syntax.

Syntax/Sample	Razor	Web Forms  Equivalent (or remarks)
Code Block	@{ int x = 123; string y = "because."; }	<% int x = 123; string y = "because."; %>
Expression (Html Encoded)	<span>@model.Message</span>	<span><%: model.Message %></span>
Expression (Unencoded)	<span> @Html.Raw(model.Message) </span>	<span><%= model.Message %></span>
Combining Text and markup	@foreach(var item in items) { <span>@item.Prop</span> }	<% foreach(var item in items) { %> <span><%: item.Prop %></span> <% } %>
Mixing code and Plain text	@if (foo) { <text>Plain Text</text> }	<% if (foo) { %> Plain Text <% } %>
Using block	@ using (Html.BeginForm()) { <input type="text" value="input here"> }	<% using (Html.BeginForm()) { %> <input type="text" value="input here"> <% } %>
Mixing code and plain text (alternate)	@if (foo) { @:Plain Text is @bar }	Same as above
Email  Addresses	Hi philha@example.com	Razor recognizes basic email format and is smart enough not to treat the @ as a code delimiter
Explicit Expression	<span> ISBN @(isbnNumber)</span>	In this case, we need to be explicit about the expression by using parentheses.
Escaping the @ sign	<span>In Razor, you use the @@foo to display the value of foo</span>	@@ renders a single @ in the response.
Server  side Comment	@* This is a server side multiline comment *@	<%-- This is a server side multiline comment --%>
Calling generic method	@(MyClass.MyMethod<AType>())	Use parentheses to be explicit about what the expression is.
Creating a Razor Delegate	@{ Func<dynamic, object> b = @<strong>@item</strong>; } @b("Bold this")	Generates a Func<T, HelperResult> that you can call from within Razor. See this blog post for more details.
Mixing expressions and text	Hello @title. @name.	Hello <%: title %>. <%: name %>.
NEW IN RAZOR v2.0/ASP.NET MVC 4
Conditional attributes	<div class="@className"></div>	When className = null <div></div> When className = "" <div class=""></div> When className = "my-class" <div class="my-class"></div>
Conditional attributes with other literal values	<div class="@className foo bar"> </div>	When className = null <div class="foo bar"></div> Notice the leading space in front of foo is removed.  When className = "my-class" <div class="my-class foo bar"> </div>
Conditional data-* attributes.  data-* attributes are always rendered.	<div data-x="@xpos"></div>	When xpos = null or "" <div data-x=""></div> When xpos = "42" <div data-x="42"></div>
Boolean attributes	<input type="checkbox" checked="@isChecked" />	When isChecked = true <input type="checkbox" checked="checked" /> When isChecked = false <input type="checkbox" />
URL Resolution with tilde	<script src="~/myscript.js"> </script>	When the app is at / <script src="/myscript.js"> </script> When running in a virtual application named MyApp <script src="/MyApp/myscript.js"> </script>

Notice in the “mixing expressions and text” example that Razor is smart enough to know that the ending period is a literal text punctuation and not meant to indicate that it’s trying to call a method or property of the expression.

Let me know if there are other examples you think should be placed in this guide. I hope you find this helpful.

UPDATE 12/30/2012:I’ve added a few new examples to the table of new additions to Razor v2/ASP.NET MVC 4 syntax. Razor got a lot better in that release!

Also, if you want to know more, consider buying the Progamming ASP.NET MVC 4 book. Full disclosure, I'm one of the authors, but the other three authors are way better.