How does RequiredFieldValidator automatically stops database being updated?

Question

My previous impression of RequiredFieldValidator and similar have been that they show you an error label and set Page.IsValid false and that is it. Meaning they leave the rest of the task (preventing the use of wrong input data) to you. But today I have realised say if you use a DetailsView to insert a new record to a database, and you use validators to check the TextBoxes inside the DetailsView, they automatically prevent the database from being updated.

I would like to know how this is implemented behind the scene. I'm guessing it aborted the Page Lifecycle at Validator.PreRender event, so that database connections at later stage could not be reached? I'm probably wrong.

I'm trying to use Reflector to get inside the RequiredFieldValidator to see how it is implemented, but I don't really know where to look. Can someone give some hints?

Answer 1

This article explains the validation in detail for ASP.NET.

http://msdn.microsoft.com/en-us/library/aa479045.aspx

Validation can be both Server side and/or client side. If used, client side validation doesn't let user submit the form until it is validated. Client side validation is implemented using JavaScript and DOM. Every submit button is wired by the framework to check validation before doing post back.

Server side validation works differently. The event chain is extended between page load and event procedure call. The validation results are set, which can be interpreted by any event procedure.

In your situation I guess you have client validation on - which it prevents Form from being submitted to server and that's why no actual update to database is done.

EDIT: DetailsView control does support server side validation controls. Follow this link for details http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.detailsview.aspx#security