How do i filter and validate form fields in symfony 1.4?

Im trying to integrate a content filtering API. My plan was to use pre/post validators but I've lost may way somehow.

What i need to do is send the values to the content filtering service. If the response comes back that the content has been filtered it will also return a modified value for the field (basic profanity filtering... matches are replace with asterisks). Thats all well and good i can throw validation errors no problem - simple stuff.

However i dont want just throw errors. What needs to happen is that validation errors are thrown as normal, but the values are modified in the form for re-display.

Basically if someone posts something naughty i want them to get a validation error saying their post has been modified, they can re-submit开发者_StackOverflow社区 the now "clean" post, or they can go about editing it to make it clean without the word replacements.

But do clean on a validator either throws an error OR returns cleaned values, not both. How can i go about implementing both? This will be used on many different forms with many different field names, so modifying methods on the form or a form base class isnt really an option - it needs to happen in the validation sub-framework somehow.

You can adjust this plugin for your needs http://www.symfony-project.org/plugins/WebPurifyPlugin