ASP.NET RegularExpressionValidator, validate on a non-match?

Question

Is there a way to use the RegularExpressionValidator to validate only when the ValidationExpression does not match? In particular use a PO BOX regex to validate an address that is NOT a PO BOX.

Thanks!

Answer 1

Create a regular expression that validates NOT a PO BOX or use custom validator.

Answer 2

Just use NegativeRegularExpressionValidator :)

[ToolboxData("<{0}:NegativeRegularExpressionValidator runat=\"server\" ErrorMessage=\"NegativeRegularExpressionValidator\"></{0}:NegativeRegularExpressionValidator>")]
public class NegativeRegularExpressionValidator : RegularExpressionValidator
{
    protected override bool EvaluateIsValid()
    {
     return base.EvaluateIsValid() == false;
    }
}

Answer 3

Mike Chaliy's solution is very good, but it doesn't validate in client-side.

I think you should use a custom validator control and write a javascript function that validates not a POBox. copy pattern from regular expression validator and use this site to write your own client side validation.

Answer 4

You can effectively invert your regular expression using a negative look-ahead.

For example, consider the following regular expression that matches only a string of digits:

^\d+$

This expression could be inverted as follows:

^(?!\d+$).*$