Question

I run into similar codes like this all the time in aspx pages:

<asp:CheckBox Runat='server' ID='myid' Checked='<%# DataBinder.Eval(Container.DataItem, 'column').Equals(1) %>'> 

I was wondering what other objects I have access to inside of that <%# %> tag. How come DataBinder.Eval() and Container.DataItem are not visible anywhere inside .CS code?

Answer 1

Within <%# %> tags you have access to

1. Anything that is visible in your code-behind class (including protected methods and properties).
2. Anything declared on the aspx page using <@import @>.
3. Anything passed in as the event arguments when the ItemDataBound event is fired (e.g. RepeaterItemEventArgs, DataListItemEventArgs, etc).

Container is actually a wrapper for RepeaterItemEventArgs.Item, DataListItemEventArgs.Item, etc. So you can actually access it in code behind within your ItemDataBound events as e.Item (e normally being the event arguments parameter name).

DataBinder is also accessible in code behind by using System.Web.UI.DataBinder.

On a side note, casting the Container.DataItem is preferred over using Eval. Eval uses reflection so there’s an overhead there. In VB.NET it would be something like

<%#DirectCast(Container.DataItem, DataRow)('some_column')%> 

Or C#

<%#((DataRow)Container.DataItem)['some_column'].ToString()%>