i have just started trying to do ch. 14 exercise 3. i thought of doing the hyperlink on the image but trouble getting it working. i took a look at just the beginning of your answer. i noticed your data binding snytax starts right after the NavigateUrl= (like NavigateUrl="<%# PhotoDetails.aspx?Id=..."). i expected the syntax to be more like
NavigateUrl="PhotoDetails.aspx?Id= <%# Eval('Id') %>"
or maybe
NavigateUrl="'PhotoDetails.aspx?Id=' + <%# Eval("Id") %>"

why do you begin the "<%#" right after the navigateUrl? Doesn't the compiler get confused by stuff other than the eval or bind statements being in there? Also, is there a way to construct the syntax as i was expecting that would work?

Hi there,

The literal string "PhotoDetails.aspx?Id= is also part of the binding expression. Everything between <%# and %> is part of the binding expression and executed when the control is bound. In other words,

'<%# "PhotoDetails.aspx?Id=" + Eval('Id') %>'

means: execute the code between <%# and %>. That in turn means that this code gets executed:

"PhotoDetails.aspx?Id=" + Eval('Id')

This is how you would normally build up a string in Code Behind as well; Eval is just a method that returns the value of the request property. So, given an ID of 10 for the current item, this would result in:

"PhotoDetails.aspx?Id=" + "10"

which results in

PhotoDetails.aspx?Id=10

which is then assigned to the NavigateUrl.

Does this help?

Imar

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Imar Spaanjaars
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Author of Beginning ASP.NET 4.5 : in C# and VB, Beginning ASP.NET Web Pages with WebMatrix
and Beginning ASP.NET 4 : in C# and VB.
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