ASP.NET TextBox - is it possible to initialize text attribute with in line code <% %>

Question

I need to initialize the text attribute of the text box element with a property from some where else when actually I can simply do this from code but it will be much more convenient if it possible to do it like this:

<asp:TextBox runat="server" Text="<%= new ContextItem("title").Value %>" />

Unfortunately the above can't be done..
The issue is that this text box element repeats it self several times in the page and my question is:

Are there any suggestions how to make it cleaner then to write it again and again in the code behind?
Thank, Adler

Answer 1

OK so the basic problem here is that if you use an inline expression you can NOT use it to set a property of a server-side control outside of a binding context (using a binding expression). I have inferred that this is probably because of the timing of the evaluation of these inline expressions. You can, however, render client-side markup in this way. If you want to keep the functionality purely in your aspx file, this is the way to do it.

Edit: Based on input from Justin Keyes, it appears it IS possible to use a binding expression to set the property. You need to manually invoke Page.DataBind() to trigger the textbox to evaluate the expression (see answer below).

For instance this:

<asp:Label ID="lbl" runat="server" Text="<%= Now.ToShortDateString() %>"  />

Will produce this output:

<%= Now.ToShortDateString() %>

On the other hand this:

<%= "<span>" & Now.ToShortDateString() & "</span>"%>

Will produce this output:

7/27/2011

The "normal" way to solve this problem is just to set the Label.Text properties in a Page.Load event handler or another appropriate event handler depending on your needs, as below. This is the way I believe most people would prefer to do it, and is most easily understandable in my opinion.

Markup:

<asp:Label ID="lbl" runat="server" />

Code:

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    lbl.Text = Now.ToShortDateString()
End Sub