Create routing constraints (C #)

Use route constraints to restrict browser requests that match a specific route. You can use regular expressions to specify constraints.

For example, suppose you have defined the following route in the global. asax file of Code 1.

Code 1-Global. asax. CS

routes.MapRoute( "Product", "Product/{productId}", new {controller="Product", action="Details"} );  

Code 1 restricts a route named product. You can use the product route to film browser requests to the constraint productcontroller, such as code 2.

Code 2-controllers/productcontroller. CS

Using system. web. MVC; <br/> namespace mvcapplication1.controllers <br/> {<br/> public class productcontroller: controller <br/>{< br/> Public actionresult details (INT productid) <br/>{< br/> return view (); <br/>}< br/>}

Note that the details () Action exposed by the product controller accepts a simple parameter named productid. This parameter is an integer parameter.

The routes defined in code 1 also match the following urls:

• /Product/23
• /Product/7

However, the route does not match the following URL:

• /Product/blah
• /Product/Apple

Because details () action requires an integer parameter, sending a request containing other things instead of an integer value will cause an error. For example, if you enter URL/product/apple in your browser, you will get the error 1.

Figure 01: The page is down (click to view the full size)

You only need to include the URL with a correct integer productid. You can use the constraint when defining a URL to restrict matching routes. Code 3 is the modified product route, which contains a regular expression constraint that only matches the integer.

Listing 3-Global. asax. CS

routes.MapRoute( "Product", "Product/{productId}", new {controller="Product", action="Details"}, new {productId = @"/d+" } );  

The regular expression/d + matches one or more integers. This constraint makes the product route match the following URL:

• /Product/3
• /Product/8999

However, the following URLs do not work:

• /Product/Apple
• /Product

These browser requests are processed by other routes, or, if no matching route existsResource not foundError.

 

 

 

Address: http://www.asp.net/learn/mvc/tutorial-24-cs.aspx