def process_form(self, form, is_created):
pass<EOL>
Override this, will be called only if the current action is submitting
a create/edit form (a POST request), and is used to perform additional
action before the form is used to populate the item.

By default does nothing.

example::

    def process_form(self, form, is_created):
        if not form.owner:
            form.owner.data = 'n/a'