stores.py 文件源码

def upsert_on_index_elements(self, instance):
        """
        Upsert an event by index elements.

        Uses ON CONFLICT ... DO NOTHING to handle uniqueness constraint violations without
        invalidating the current transactions completely.

        Depends on an unique constraint on index elements to find the resulting entry.

        """
        with self.flushing():
            insert_statement = insert(self.model_class).values(
                instance._members(),
            )
            upsert_statement = insert_statement.on_conflict_do_nothing(
                index_elements=self.upsert_index_elements(),
            )
            self.session.execute(upsert_statement)

        most_recent = self._retrieve_most_recent(
            *[
                getattr(self.model_class, elem) == getattr(instance, elem)
                for elem in self.upsert_index_elements()
            ]
        )

        if not most_recent.is_similar_to(instance):
            raise ConcurrentStateConflictError()

        return most_recent