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URL Rewriting in ASP.Net

Posted by Harshit Vyas Articles | ASP.NET Programming September 24, 2010
In this article we will see a method for URL Rewriting in ASP.Net.
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Introduction

Make our URL extension smaller using code and without writing too much in the web.config.

Recently I had the chance to work with URL rewriting. After doing some research I found some modules which we need to insert in our application and write mapped URLs or regular expression which was nice but we have to do that in many pages. So finally I invented my own code which is described below.

Code explanation

If you download my code then you can see that there is not too much code. I have written just a few lines of code in global.asax file which is as follows

void Application_BeginRequest(object sender, EventArgs e)
{
    string curruntpath = Request.Path.ToLower();
    curruntpath = curruntpath.Trim();
    bool isredirected = curruntpath.EndsWith(".aspx");
    bool isredirected2 = curruntpath.EndsWith(".html");
    bool isredirected3 = curruntpath.EndsWith(".jpg");
    bool isredirected4 = curruntpath.EndsWith(".jpeg");
    bool isredirected5 = curruntpath.EndsWith(".gif");
    bool isredirected6 = curruntpath.EndsWith(".png");
    // string atr = curruntpath.Substring(curruntpath.IndexOf("/"));
    if (!isredirected && !isredirected2 && !isredirected3 && !isredirected4 && !isredirected5 && !isredirected6)
    {
        HttpContext obj = HttpContext.Current;
        string finalURL = curruntpath + ".aspx";
        if (System.IO.File.Exists(Server.MapPath(finalURL)))
        {
            obj.RewritePath(finalURL);
        }
        else
        {
            obj.RewritePath("Error.aspx");
        }
    }
    if (curruntpath.EndsWith(".aspx"))
    {
        HttpContext obj = HttpContext.Current;
        obj.RewritePath("Error.aspx");
    }
}

First let me clarify what I have done with this code
  1. Make my page extension smaller
  2. I hid the aspx extension. For any request with this extension I simply redirect the page to my custom page error.aspx
  3. Also if any request comes for a page which is not available or has been moved I can show some relevant message but currently I have redirected them to the error.aspx page 
  4. Make the URLs friendly
Now let me explain the code:-

First thing is I have written my code in the Application_BeginRequest

It is the only event which fires every time when the page is going to call although you can also use the handler to achieve the same thing. 

First I have to make the list of items which are generally called when the page is loading like some images, css file and check for their request.

Here it is good to know that in Application_BeginRequest all the files are coming not only on one request all of the request comes so to avoid redirection of them I have made some conditions.

In the next step I am checking whether requested page is in my application or not. If yes then rewrite else redirect to error page.

Here URL will remain the same as end user has typed in his address bar.

See the below images

2.gif

Image 1

3.gif  

Image 2

Finally I want mysite's extension to be hidden so for all conditions that come with  the extension .aspx I redirect them to some other page.

4.gif

Image 3

So now URL rewriting has been completed.

Now, in your hyperlinks you just give the URL like...

<asp:HyperLink ID="HyperLink1" runat="server" NavigateURL="~/Default2"> Goto second page</asp:HyperLink>

Some other types to rewrite URL:-

By editing in the web.config file-

To do this you simply need to add these lines

<urlMappings>
        <add url="~/Default" mappedUrl="~/default.aspx"/>
</urlMappings>

In the web.config under <system.web> section here you need to add url and mapped url as you can see the above this feature is given by .net team from visual studio 2005. It is extreamly easy to rewrite url if you have to do this in small number of pages as it is not good idea to write this sentences for lots of pages.

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