I'm writing an asp.net user control. It has a property, FurtherReadingPage, and two controls bound to it: ObjectDataSource and a Repeater. Inside the Repeater I would like to display a hyperlink with an href property set to something like FurtherReadingPage + "?id=" + Eval("Id"). I don't know how to do it inside the page's markup. I can use <% Eval("Id") %> or <% Response.Write(FurtherReadingPage + "?id=") %> alone but I don't know how to mix them.
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4 Answers
You have a couple of different tags:
<% executes the code inside:
<% int id = int.Parse(Request["id"]); %>
<%= writes out the code inside:
<%=id %> <!-- note no ; -->
<!-- this is shorthand for: -->
<% Response.Write(id); %>
Both of these break up the normal flow when rendered on a page, for instance if you use them in a normal Asp.net <head runat="server"> you'll get problems.
<%# databinding:
<%# Eval("id") %>
This allows you to specify the bindings for controls that Asp.net WebForms render as a collection (rather than the literal controls that you can use <%= with), for instance:
<!-- this could be inside a repeater or another control -->
<asp:Hyperlink runat="server" ID="demo"
NavigateUrl="page.aspx?id=<%# Eval("id") %>" />
<% //without this bind the <%# will be ignored
void Page_Load( object sender, EventArgs e ) {
demo.DataBind();
//or
repeaterWithManyLinks.DataBind();
}
%>
For your specific case you either:
- Use a repeater and
<%# Eval(...) %>withrepeater.DataBind();
or
- Use a foreach loop (
<% foreach(... %>) with<%= ... %>
Comments
You can do it like this -
<asp:Hyperlink runat="Server" ID="hlLink" NavigateUrl='<%# FurtherReadingPage + "?Id=" + DataBinder.Eval(Container.DataItem, "Id") %>' />
Comments
Try this:
<%#String.Format("{0}?id={1}",FurtherReadingPage, Id)%>
Comments
Try this (example as link): <a href='<%=FurtherReadingPage %>?id=<%# Eval("Id") %>'>My link</a>
3 Comments
Keith
This mixes <%= and <%#, which will create problems in most circumstances. <%= won't work inside a Repeater and <%# won't work unless DataBind() is called.
Sergio
@Keith: You are wrong. I just tried <%= "Test" %> inside a repeater to double check and it works ok. <%# only works with Databind() which is the case.
Keith
Sorry, yes, <%= can work in repeaters, depending on the control hierarchy above not containing any collection style controls. Basically <%= FurtherReadingPage %> will sometimes work in a repeater, while <%# FurtherReadingPage %> always will.