Question

I am using a RangeValidator to validate that a year is between a static start year and a dynamic end year (the current year). I am drawing a huge blank for setting the maximum value in this fashion:

MaximumValue='<% DateTime.Now.Year %>'

Any help is appreciated as I usually don’t set max values in this fashion.

Edit:
So I have been given the following ways to incorporate the code into the codebehind:

1. validator init event
2. page prerender
3. and i’m a newb and would just have done on page load

which is best?

Answer 1

By default, ASP.NET doesn’t let you do this; the <%= ... %> syntax doesn’t work either.

The easiest way is to just set the MaximumValue property in the code-behind, in the validator’s Init event. (This is better than the page’s Init, Load, or PreRender event, which would bloat view state.)

protected void rangeValidator_Init(object sender, EventArgs e)
{
    ((RangeValidator)sender).MaximumValue = DateTime.Now.Year.ToString();
}

By using the sender parameter, multiple RangeValidator controls on the page can all share this event handler.

If you really wanted to set the MaximumValue in the .ascx/.aspx, then take a look at this blog post: The CodeExpressionBuilder.

UPDATE: Setting MaximumValue in Init, Load, and PreRender would all work. Init has the slight advantage that it avoids increasing the size of view state. PreRender has the additional disadvantage that server-side validation would break if view state were disabled for the validator.