Data binding along with the value in ASP.NET - asp.net

Question

How do you achive something like below in asp.net?
<asp:Label runat="server" Text="The '<%# CustomValue %>' you assigned."/>

Answer 1

This usually depends on where your Label resides. If it is a stond alone control, not nested inside a repeater, you just set your code in code behind:
Label1.Text = $"The {CustomValue} you assigned.";
If the label is nested inside an ItemTemplate in some sort of Repeater control, you can strongly type it to an objects property:
<asp:Repeater runat="server" ID="MyRepeater" ItemType="WebFormsSandbox.Person">
<ItemTemplate>
<li>
<%#: Item.FirstName %> <%#: Item.LastName %>
</li>
</ItemTemplate>
</asp:Repeater>
and the corresponding code behind:
protected void Page_Load(object sender, EventArgs e)
{
MyRepeater.DataSource = Persons();
MyRepeater.DataBind();
}
IEnumerable<Person> Persons()
{
for (int i = 0; i < 10; i++)
{
yield return new Person { Id= i, FirstName = $"Foo{i}", LastName = $"Bar{i}" };
}
}
This would create a list of links, where you then could do anything with it. Whether this would pop up a custom window or does a postback .. up to you.

Answer 2

If you really want to do it that way, write the string inside the server tags.
<asp:Label runat="server" Text='<%# "The " + CustomValue + " you assigned." %>'/>
However if the Label is not inside a GridView, Repeater etc you have to call DataBind manually.
protected void Page_Load(object sender, EventArgs e)
{
DataBind();
}

Answer 3

You would typically do this in the code behind on page load, unless you were using a datagrid or repeater control. Assign an ID to your control and reference it like so.
<asp:Label runat="server" ID="Label1" />
protected void Page_Load(object sender,EventArgs e)
{
Label1.Text = "Your Value";
}