Django field, form and model validation process
Django's form and field validation process can be best understood by looking at the code in django's BaseForm class (in django.forms.forms) - see below. See also this blog post for a graphic overview. The form.full_clean() method is called by django at the start of the validation process (by form.is_valid(), usually immediately after the view receives the posted data). full_clean() performs a 3 phase validation , with each phase corresponding to a call of one of the protected methods below: self._clean_fields() : Field validation This method iterates over the form fields: For each field, it calls the Widget's value_from_datadict() method, passing the complete post data in a QueryDict. The Widget's task is to retrieve its own value from this QueryDict and return it. The returned value is then passed to the Field's own clean() method. This method does the initial validation (e.g. checking if the value is not empty), without touching the db. If the Field's...
