Question

When binding values to controls I have plenty of this:

Text='<%# Bind("StartDate", "{0:dd.MM.yyyy}") %>'

However I would like to extract this format (and few others) to helper. And this is what I did:

public static class DateTimeExtension
{
    public const string CalendarDateFormat = "{0:dd.MM.yyyy}";
    public const string CalendarMonthFormat = "{0:MM.yyyy}";

    public static string ToCalendarDate(this DateTime dateToFormat)
    {
        return string.Format(CalendarDateFormat, dateToFormat);
    }

    public static string ToCalendarMonthDate(this DateTime dateToFormat)
    {
        return string.Format(CalendarMonthFormat, dateToFormat);
    }
}

Yet now, when I change my Bind call to something like this:

Text='<%# Bind("StartDate", DateTimeExtension.CalendarDateFormat) %>'

I get an exception:

System.Web.HttpException: A call to Bind was not well formatted.  Please refer to documentation for the correct parameters to Bind.

I have namespaces configured in web.config so that shouldn’t be an issue. Is there a way to achieve what I like?

Answer 1

Try using Eval as Bind expression is a very specialized part of ASP.NET code generation and it has a limitation that the format parameter must be a literal.

Text='<%# Eval("StartDate", DateTimeExtension.CalendarDateFormat) %>' 

Read more about Bind and Eval here.