Monday, April 6, 2009

URL rewriting / mapping in ASP.Net

URL rewriting or mapping is an important feature of a web application, by which you can give search engine friendly URLs in your application and provide extra security to your application.

following is very simple approach, how to do that-

1) You need to add following section in your Web.config

<urlMappings enabled="true">
<add url="~/fakename.aspx" mappedUrl="~/actualpageurl.aspx" />
<add url="~/Registration.aspx" mappedUrl="~/signup.aspx" />

2) Add ASp.Net folder "App_Browsers" in your application

3) Add a new item in that folder as "Form.browser"

Code- Form.browser


<browser refID="Default">
<adapter controlType="System.Web.UI.HtmlControls.HtmlForm"
adapterType="FormRewriterControlAdapter" />


4) Create a class file as follows


using System;
using System.Web.UI;
using System.Web;

public class FormRewriterControlAdapter : System.Web.UI.Adapters.ControlAdapter

protected override void Render(System.Web.UI.HtmlTextWriter writer)
base.Render(new RewriteFormHtmlTextWriter(writer));

public class RewriteFormHtmlTextWriter : HtmlTextWriter

public RewriteFormHtmlTextWriter(HtmlTextWriter writer)
: base(writer)
this.InnerWriter = writer.InnerWriter;

public RewriteFormHtmlTextWriter(System.IO.TextWriter writer)
: base(writer)
base.InnerWriter = writer;

public override void WriteAttribute(string name, string value, bool fEncode)

// If the attribute we are writing is the "action" attribute, and we are not on a sub-control,
// then replace the value to write with the raw URL of the request - which ensures that we'll
// preserve the PathInfo value on postback scenarios

if ((name == "action"))

HttpContext Context = default(HttpContext);
Context = HttpContext.Current;

if (Context.Items["ActionAlreadyWritten"] == null)

// Because we are using the HttpModule, we will use the
// Request.RawUrl property within ASP.NET to retrieve the origional URL
// before it was re-written. You'll want to change the line of code below
// if you use a different URL rewriting implementation.

value = Context.Request.RawUrl;

// Indicate that we've already rewritten the <form>'s action attribute to prevent
// us from rewriting a sub-control under the <form> control

Context.Items["ActionAlreadyWritten"] = true;


base.WriteAttribute(name, value, fEncode);


5) Thats all and you are ready to rewrite your incoming URLs without any complex code for HTTP-module
and any actionless form.

IMPORTANT: If you go for Actionless form then it has a side effect that disables page validators.

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Amit said...

Any idea how to achieve this in Sharepoint . Means where to add this browser tag if I want the same functionality for built in links in sharepoint.

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alok_smart said...

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