In this example, we will simply check the length of the string in the TextBox. This is a very basic and that useful example, only made to show you how you may use the CustomValidator.
As you can see, it’s pretty simple. The only unknown property is the onservervalidate event. It’s used to reference a method from CodeBehind which will handle the validation. Switch to our CodeBehind file and add the following method:
Hope this will Help you !!!