Validate fields with JavaScript or Servlet?

[Barry Andrews]

Hi All,
My question is in 2 parts:
First, I was wondering if there is any benefit to validating a field using JavaScript or just letting the servlet do it? I want to first make sure the field is not blank before invoking the servlet. I was thinking that performance wise, this approach would be better, but I don't know. What do other's think.
Also, if I did allow JavaScript to validate the fields, how would I go about doing this? The form always tries to invoke the servlet before calling the JavaScript function. Is this possible to do?
Thanks for your help!
Barry

[Barry Andrews]

Please disregard the second part of the question. I figured that one out. I would still like thoughts on the first though.
thanks,
Barry

[Juanjo Bazan]

About your first question: You should validate every field in your servlet. To do it using javascript is good for avoiding a lot of incorrect requests but javascript is really easy to 'bypass'. Everyone could call the servlet just writing the url in the address bar.
Best solution: Validate twice. Client and Server -side.
HTH

[Barry Andrews]

Yes, I never thought about that. Good point!

thanks,
Barry

[Val Pecaoco]

Hi Barry,
I would like to recommend that you use Struts (because I know someday you will, so why not do it now ), wherein you could automatically enable form validation using ActionForm objects. This will let you separate validation from your main business code (which is cool ). Usually what I do is double-layer validation - on the client side using JavaScript and on the server side using ActionForm objects. Either way it's a win-win situation.
Ex Animo Java!
-- Val
[ July 28, 2002: Message edited by: Val Pecaoco ]

[georgejk]

Hai
Yes I agree with My friend Mr.Val Pecaoco has pointed out. Struts gives you a frameowrk to do all of ur validations. Its very simple to learn also. You can set your own error messages for one particular validation.
visit http://jakarta.appache.org/struts/
for more information.
regards Georgie

[Jessica Sant]

I agree with the above posts -- I'd put it in JavaScript so that validation occurs on the Client-side (avoids processing on the server-side). However, if someone has JavaScript disabled -- you're hooped, so definately re-validate it on the Server-Side with Struts (will give you a new technology to learn/master too!)
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