Applied ASP.NET 4 in Context

Using Server-Side Validation

So far, the Web Forms validation support has been remarkably similar to the jQuery validation support demonstrated in Chapter 10. In fact, the Web Forms validation system has a significant advantage, which is that the validation performed using JavaScript on the client is performed again on the server when the user posts the form.

In Chapter 10, I warned you that relying on client-side validation alone is a dangerous thing to do. Not only does this preclude validation when JavaScript is disabled in the browser, but you also make it very easy for someone to forge a request and send you bad data values, causing problems in your application. Figure 17-14 shows the validation at work when JavaScript is disabled in the ...