Handling Form Errors with context.RewritePath

[shurlandmoore]

I recently used HttpContext.Rew ritePath in my global.asx page in asp.net 4.0. The url rewrite worked fine but the was a caveat, when i try to submit the form i got error 404. I realized that the action property of my form was not pointing to the correct url (the most common problem with RewritePath method). So I came up with the following work around. Hope this could help someone who experiencing the same problem.

my first work around... create a method that finds the current page including querystring. Once the page is found stick it into the form action. You can use the page PreRender event for that. Example


''' <summary>
''' Gets this page name
''' </summary>
''' <returns>Curren t Working Page Url</returns>
Protected Function GetCurrentUrl(B yVal includingQstrin g As Boolean) As String
Dim Url As String = String.Empty
If HttpContext.Cur rent Is Nothing Then
Return Url
End If

If includingQstrin g Then
Dim host As String = ResolveHost(Fal se)
If host.EndsWith("/") Then
host = host.Substring( 0, host.Length - 1)
End If
Url = host + HttpContext.Cur rent.Request.Ra wUrl
Else
Url = HttpContext.Cur rent.Request.Ur l.GetLeftPart(U riPartial.Path)
End If
Return Url
End Function


''' <summary>
''' Resolves the host location
''' </summary>
''' <param name="secured"> Use secure socket layer; true/false</param>
''' <returns>Stor e host location</returns>
Protected Function ResolveHost(ByV al secured As Boolean) As String

Dim retval As String = "http://" & ServerVariables ("HTTP_HOST" )
Dim prefx = "http://www."

If Not retval.Contains (www) Then
If Not HttpContext.Cur rent.Request.Ur l.IsLoopback Then
retval = retval.Replace( "http://", prefx)
secured = False
End If
End If

If secured Then
If Not OwnSSL Then
retval = SharedSSL
Else
retval = retval.Replace( "http:/", "https:/")
End If
Else

retval = retval.Replace( "www.www", "www")
If Not retval.EndsWith ("/") Then
retval = retval & "/"
End If

Return retval
End Function

Now that we've got this function, in the page prerender add the following:

Protected Overrides Sub OnPreRender(ByV al e As EventArgs)
form1.Action = Me.GetCurrentUr l(True)
MyBase.OnPreRen der(e)
End Sub


That's it for the first workaround!


Workaround 2:

First we need to create a custom form that inherits from HtmlForm Class

NameSpace RewriteFormWork around
Public Class MyCustomForm
Inherits System.Web.UI.H tmlControls.Htm lForm

Protected Overrides Sub RenderAttribute s(ByVal writer As HtmlTextWriter)
Attributes.Add( "action", GetCurrentUrl(T rue))
Attributes.Add( "id", "myform")
Attributes.Add( "method", "Post")
Attributes.Rend er(writer)
End Sub
End NameSpace

Add the following directive to your page :
<%@Register TagPrefix="cf" NameSpace="Rewr iteFormWorkarou nd" Assembly="MyCus tomForm" %>


Replace your existing form with the following:
<cf:Form runat="server" id="form1">
......
</cf:Form>


Hope this helps someone!!