The Redirect method of the Response object operates by
sending a header to the client. This header causes the client to look to
another URL location specified in the header. Because a header must come at the
beginning of a document, it is not possible to place the Redirect method in a
document with HTML code preceding it.
To work around this behavior
you can use the buffering capabilities of the Response object. In doing this
you can output HTML code into the buffer until you reach a point where you use
the Redirect method. If at this point you need to redirect to another page, you
clear the buffer and then issue the Response.Redirect.
Example error
When trying to use the Response.Redirect method in a
server-side script, the following error can occur when the page is accessed:
Response object error 'ASP 0156 : 80004005
Header
Error
/<page.asp>, line 9
The HTTP headers are already written
to the client browser. Any HTTP header modifications must be made before
writing page content.
Example ASP
The following example Active Server Pages (ASP) code demonstrates
this concept:
<%
' Begin buffering the HTML
' Note this MUST happen before the initial <HTML> tag.
Response.Buffer = True
%>
<HTML>
<BODY>
HTML code before potential redirect.<P>
<%
' Change the following line as appropriate for your script
If 1 = 1 Then
Response.Clear
Response.Redirect "filename.asp"
End If
%>
Code to be added
Use the following additional HTML code after the redirect:
<%
' The following causes the HTML to actually be sent to the client.
' Up to this point, no HTML has actually been downloaded to the client
' browser.
Response.End
%>
</BODY>
</HTML>
The above example always redirects to the file named
Filename.asp.
Note Setting the Response.Buffer = True is not necessary in Windows
2000 because it is True by default.