Good morning,

Reading a recent thread about accessing jQuery Validation from Wicket reminded 
me that I've developed some code that might be of use.  I'm not sure if this is 
something anyone else would be interested in or if it's something that might 
eventually be integrated into Wicket core or if it would be more appropriate 
for one of the existing jQuery/Wicket integration libraries.  I wanted to 
describe what I've cooked up so far.  If this is anything that would be useful, 
I'd be willing to clean the code up a bit to extract a few bits that are 
specific to our environment and post the code somewhere.

My intent was to get client-side validation using Wicket's existing validation 
classes without requiring AJAX calls to make them work and preferably without 
requiring Page's to include lots of unsightly JavaScript.  Also, not 
duplicating validation logic on the client & server tiers was desirable.  The 
code was originally developed for a site that was expected to receive a high 
amount of traffic in a short period of time, and avoiding unnecessary server 
calls was a priority.  

I created a subclass of Form (ClientSideValidatingForm) which examines each 
FormComponent (and sub-Form) added to it and extracts information about the 
standard Wicket validations.  It generates JavaScript which uses jQuery's 
Validator library to apply client-side checks equivalent to the Wicket server 
side checks.  The nice thing about this is that you get client-side validation 
for "free" just by adding the normal Wicket validations plus you still get all 
your validations backed up in the server side in case JavaScript is unavailable 
or disabled.

The implementation of the class does lack a bit in terms of elegance 
unfortunately.  As the Wicket validation interface doesn't currently know 
anything about JavaScript, it was necessary to run a chain of instanceof checks 
against all the known Wicket validations and emit JavaScript to mirror their 
logic.  I also created an extension of the Wicket IValidator interface which 
can provide JavaScript functions to perform validation equivalent to the 
server-side Java code.  The extraction code in ClientSideValidatingForm 
preferentially checks for this interface and uses provided JavaScript if 
available.  Otherwise, it's a bunch of instanceof's to check for known 
validations or log an error if an unknown instance of IValidator is found.

Long term, it would be helpful if the stock Wicket IValidator interface could 
include a method to get JavaScript validations for all of the stock validations.

The code is pretty tightly bound to jQuery Validator at this point, but it's 
likely the methodology could be abstracted to other validation frameworks.  
It's also built using WiQuery, though that's mostly as a convenience to get the 
same version of jQuery that we use elsewhere.  The same could easily be 
implemented without WiQuery provided a version of jQuery was contributed to the 
response via some other mechanism.

Is this something anyone would be interested in?  

Best regards,
Zac Bedell

(Apologies if this is a dupe. I had some email client config issues this 
morning...)


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