models.py

    def clean(self):
        """ Validate site and people resource ids with Doorman """
        if settings.FEATURE_DOORMAN_VALIDATION_ON:
            doorman = DoormanClient()
            if hasattr(self, 'site'):
                if not doorman.resource_exists(resource='sites', resource_id=self.site):
                    raise ValidationError('Invalid site id: {0}'.format(self.site))
            if hasattr(self, 'editor'):
                if not doorman.resource_exists(resource='people', resource_id=self.editor):
                    raise ValidationError('Invalid editor id: {0}'.format(self.editor))
            if hasattr(self, 'author'):
                if not doorman.resource_exists(resource='author-profiles', resource_id=self.author):
                    raise ValidationError('Invalid author id: {0}'.format(self.author))