Using c# in Web Forms to passing parameter to user control

问题

From an aspx page, I am trying to display a user control for each item in a collection, but the C# seems to be ignored when tryign to set the UserControl parameter:

<%foreach (Fetus item in this.pregnancy.Fetus) {%>
    //this returns a GUID:
    "<%= item.Id.ToString() %>" 

    //this does not work, returns the characters between "" like < %= item.Id.ToString()%>:
    <uc1:AntepartumCTGChart runat="server" ID="AntepartumCTGChart" FetusId="<%= item.Id.ToString()%>" />
<% } %>

I would expect this to work, what's wrong?

回答1:

You have to use a data binding expression

<uc1:AntepartumCTGChart runat="server" ID="AntepartumCTGChart" FetusId='<%# item.Id.ToString()%>' />

But you have to call DataBind() in code behind for that to work.

You can also use a Repeater

<asp:Repeater ID="Repeater1" runat="server">
    <ItemTemplate>
        <uc1:AntepartumCTGChart runat="server" ID="AntepartumCTGChart" FetusId='<%# Eval("id").ToString()%>' />
    </ItemTemplate>
</asp:Repeater>

And then bind data to it in code behind

Repeater1.DataSource = pregnancy.Fetus;
Repeater1.DataBind();

来源：https://stackoverflow.com/questions/48811256/using-c-sharp-in-web-forms-to-passing-parameter-to-user-control