def update(self, notice: Notice):
assert notice.is_empty() == False
# 存在则更新，不存在则新建
self.collection.update_one({'nid': notice.nid},
{'$set': notice.to_dict()},
upsert=True)
def add(self, notice: Notice):
# self.collection.insert_one(notice.to_dict())
assert notice.is_empty() == False
self.update(notice)