Partial validation using cakephp

I'm new to cakePHP I want to know if there's a way to validate a form partially as in JavaScript.

Situation:

I have a select box with 2 opt开发者_Python百科ions - 1. free, 2. paid

When paid is chosen a text input field appears for a price.

Any ideas?

Thanks in advance.

You can do custom validation rules. So, your form would validate differently, depending on if it's a paid user or a free one.

This link will give you some ideas of how to get started with it:

http://bakery.cakephp.org/articles/aranworld/2008/01/14/using-equalto-validation-to-compare-two-form-fields