ASP.NET Server Tag Not Parsing in URL Field

Experts,

I'm banging my head against a wall here, and I'm sure this is a simple syntax issue.  I am working with a ListView control, and I'm trying to construct a hyperlink that parses a datafield into the query string of a URL (the page that is being called in the URL serves the image data from the provided filename back as a filestream because the image being called resides in a location outside the application folder.)

<asp:HyperLink	runat="server"
		NavigateUrl='~/ServeFFAttachment.aspx?FileName=<%# Eval("ATTACHMENT_PATH") %>'
		Target="_blank">
	<%# Eval("ATTACHMENT_DESC") %>
</asp:HyperLink>

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The server doesn't choke on the code, but the URL that gets associated with the hyperlink isn't evaluating the server tag (see below.)

http://serverfqdn:55555/ServeFFAttachment.aspx?FileName=<%# Eval("ATTACHMENT_PATH") %>

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I should point out that this worked fine before I added the ASPX page to the URL (code below worked...)

<asp:HyperLink	runat='server'
		NavigateUrl='<%# Eval("ATTACHMENT_PATH") %>'
		Target='_blank'>
	<%# Eval("ATTACHMENT_DESC") %>
</asp:HyperLink>

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Why does adding "~/ServeFFAttachment.aspx?FileName=" before the Server Tag mess it up??

HELP!!  :-)

Thanks,

John
John ParkerService Quality ManagerAsked:
Who is Participating?
 
Robert SchuttSoftware EngineerCommented:
When you want to include a binding value in the url attribute, the whole value needs to be generated from within the asp tags.

One possible way would be:
NavigateUrl='<%# Eval("ATTACHMENT_PATH", "~/ServeFFAttachment.aspx?FileName={0}") %>'

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Note that the query parameter in your generated url should actually be url encoded to make valid html, if that's important in your case you could try something like:
NavigateUrl='<%# String.Format("~/ServeFFAttachment.aspx?FileName={0}", HttpUtility.UrlEncode(Eval("ATTACHMENT_PATH"))) %>'

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John ParkerService Quality ManagerAuthor Commented:
Robert,

That was it!  Thank you very much for the quick response!  I did have to make one minor change to the use of the URLEncoded function...  I had to add the ToString method to the Eval function for it to work.  Otherwise the compiler didn't like it.

NavigateUrl='<%# String.Format("~/ServeFFAttachment.aspx?FileName={0}", HttpUtility.UrlEncode(Eval("ATTACHMENT_PATH").ToString())) %>' 

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Thanks again!

John
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