def prefill_form(self, form, pk):
pass<EOL>
Override this, will be called only if the current action is rendering
an edit form (a GET request), and is used to perform additional action to
prefill the form.

This is useful when you have added custom fields that depend on the
database contents. Fields that were added by name of a normal column
or relationship should work out of the box.

example::

    def prefill_form(self, form, pk):
        if form.email.data:
            form.email_confirmation.data = form.email.data