Page-Contract is a python product that allows for easy form/input validation from python scripts, dtml, and python products.

it adds a new type of dtml-tag to your zope installation. dtml-contract is a multi-purpose tag that is designed to provide documentation, marshalling and filtering of request data, and custom error handling of the request data. the documentation comes from a read only section of the contract which should describe the purpose of the object, its author, and some information about its parameters. the marshalling and filtering is done by naming variables expected in the request and associating one or more filters with those variables. PageContract comes with a set of prebuilt filters although it can easily be extended by writing new filters. lastly it allows association of different error handlers to different variables. an example of using it from a python script lives at http://www.zopelabs.com/cookbook/1008972251