CodeClimber

Validators are a great part of the ASP.NET framework: they provide a standardized and easy way to add validation to form fields. But even if the framework provides different kinds of validators, there are so many different validations patterns that sometimes you have to write custom code to match your specific requirements. I wrote a post a few months ago about how to write a custom validator for a Checkbox list, but I was dealing with a completely new validation pattern. But what if I only want to enable the validation of certain field based on certain conditions? Or...

If you add a normal RequiredFieldValidator and you want to validate a CheckBoxList, you will get a runtime exception informing you that the CheckBoxList cannot be validated. Sometimes you want to make sure the that user has selected at least one of the checkbox in the checkbox list, but as aforementioned, if you user a normal RequiredFieldValidator you will get an exception. You could use a CustomValidator control, but a nicer and more reusable approach is to build a custom web control that extends the BaseValidator. I found a 2001 article on how to do that (Building a CheckBoxList Validator Control) but...