ASP.NET MVC Tip #3: Client-side form validation made easy – Part 1

Client-side form validation has become a de-facto standard for modern web applications. However, replicating server-side validation rules on the client side can be a tedious and error-prone process.

In addition, there are some validation rules which cannot be checked completely on the client side, for example because the validation depends on information stored in the server database. For those rules you need to implement remote client-side form validation.

The xVal framework is great for automatic generation of client-side validation code for some of your server-side validation rules, but it does not support remote client-side validation.

This article shows a fully generic way to implement remote client-side form validation so that

• Validation rules remain solely in your ASP.NET MVC model
• You write each validation rule just once, and only in easily testable C# code. There is no JavaScript or other client-side counterpart .
• There is no need to branch or otherwise modify xVal or jquery.validate
• All you have to do for each new remote form validation rule is to derive from the base class shown in this article.

I’ll describe how to implement this in detail. I’ve also uploaded a demo project showing how this works in action.

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