Formatting DataBinder.Eval data

There is an optional overload for DataBinder.Eval to supply formatting:

<%# DataBinder.Eval(Container.DataItem, "expression"[, "format"]) %>

The format parameter is a String value, using the value placeholder replacement syntax (called composite formatting) like this:

<asp:Label id="lblNewsDate" runat="server" Text='<%# DataBinder.Eval(Container.DataItem, "publishedDate", "{0:dddd d MMMM}") %>'</label>

After some searching on the Internet I found that it is in fact very much possible to call a custom method passing the DataBinder.Eval value.

The custom method can be written in the code behind file, but has to be declared public or protected. In my question above, I had mentioned that I tried to write the custom method in the code behind but was getting a run time error. The reason for this was that I had declared the method to be private.

So, in summary the following is a good way to use DataBinder.Eval value to get your desired output:

default.aspx

<asp:Label ID="lblNewsDate" runat="server" Text='<%# GetDateInHomepageFormat(DataBinder.Eval(Container.DataItem, "publishedDate")) )%>'></asp:Label>

default.aspx.cs code:

public partial class _Default : System.Web.UI.Page{    protected string GetDateInHomepageFormat(DateTime d)    {        string retValue = "";        // Do all processing required and return value        return retValue;    }}

Hope this helps others as well.

Why not use the simpler syntax?

<asp:Label id="lblNewsDate" runat="server" Text='<%# Eval("publishedDate", "{0:dddd d MMMM}") %>'</label>

This is the template control "Eval" that takes in the expression and the string format:

protected internal string Eval(string expression,string format

)

http://msdn.microsoft.com/en-us/library/3d2sz789.aspx