Summary

Validation is a core feature of all Web applications. It adds a professional touch to the UI of an application. More important, validation provides a basic layer of input verification before any application logic acts upon the data entered by the user . ASP.NET provides a set of validation controls that are useful across a wide range of scenarios. In addition, ASP.NET offers an extensible framework that allows component developers to create custom validators with new and more specialized validation rules. The validation framework also makes it possible to provide enhanced client-side validation functionality without any effort on the page developer's part.

In this chapter, we looked at the implementation of a custom validator named StringValidator , which works the same way as any other built-in validator. In Chapter 17, "Localization, Licensing, and Other Miscellany," we will give another example of a custom validator, PhoneNumberValidator , in the context of implementing configurable properties.