Question

The contents of my form must be submitted to another application server for validation and execution (specifically, I call a RESTful web service with the posted values in the form). The service will either return a 200 SUCCESS or a 400/409 error with a body that describes the exact field errors.

When should I do this submission? Should I do it in the view:

if form.is_valid:
    result = submit_to_service(POST)
    if result.code in (400, 409):
        somehow_set_errors_on_the_form(form)
    else:
        go_on...

Or in the Form.clean method?

def clean(self):
    result = submit_to_service(POST)
    if result.code in (400, 409):
        for field in result.errors:
            self._errors[field].append(result.errors[field])
    else:
        pass

Which of these is clearer?

Answer 1

validation and execution

No execution or stateful changes in the form clean(). Please. The form’s clean() should only mess with data on the form, not anywhere else.

If there is a stateful change, it must be in a view function inside a non-GET request handler.