Flashes an error message for Hidden/CSRFToken fields on form submit

HiddenValidationMixin.py

class HiddenValidationMixin(wtf_Form):
    def validate_on_submit(self):
        valid = super(wtf_Form, self).validate_on_submit()
        if not valid and request.method == 'POST':
            for k, v in self.errors.iteritems():
                if k not in self.data:
                    flash('{0}: {1}'.format(k, v), 'error')
                else:
                    attr = self.__getattribute__(k)
                    if attr and hasattr(attr, 'type'):
                        if attr.type in ['CSRFTokenField', 'HiddenField']:
                            flash('{0}: {1}'.format(k, v), 'error')
        return valid