def _delete_collection(self, ctx):
        """
        Delete a collection from DB, optionally filtered by ``filter_by``
        """
        assert isinstance(ctx, ResourceQueryContext)

        filter_by = ctx.get_filter_by()
        q = self._orm.query(self.model_cls)

        if filter_by is not None:
            q = self.to_filter(q, filter_by)

        return q.delete()