烧瓶棉花糖嵌套模式不适用答案

【问题标题】：flask-marshmallow nested schema doesn't apply烧瓶棉花糖嵌套模式不适用
【发布时间】：2019-11-04 04:33:12
【问题描述】：

我目前正在制作一个带有 get 请求的 API，以返回 2 个模型的连接 json 数据，这些模型使用 flask、sqlalchemy 和 flask-sqlalchemy（用于查询）和 flask-marshmallow（用于序列化为 JSON）具有关系

我的模型：

class Recording(Base):
    __tablename__ = 'recordings'

    id = Column(Integer, primary_key=True)
    filepath = Column(String, nullable=False)

    language_id = Column(Integer, ForeignKey('languages.id'), nullable=False)
    language = relationship("Language", back_populates="recordings")

    user_id = Column(Integer, ForeignKey('users.id'), nullable=False)
    user = relationship("User", back_populates="recordings")

    created_at = Column(DateTime, nullable=False, default=func.now())
    updated_at = Column(DateTime, nullable=False,
                        default=func.now(), onupdate=func.now())
    deletedd_at = Column(DateTime, nullable=True)

    def __repr__(self):
        return 'id: {}'.format(self.id)

User.recordings = relationship("Recording", order_by=Recording.id, back_populates="user")
Language.recordings = relationship("Recording", order_by=Recording.id, back_populates="language")


class RecordingResult(Base):
    __tablename__ = 'recording_results'

    id = Column(Integer, primary_key=True)
    is_with_dictionary = Column(Boolean, default=False)
    result = Column(String, nullable=True)
    run_time = Column(Float, default=0.0)

    recording_id = Column(Integer, ForeignKey('recordings.id'), nullable=False)
    recording = relationship("Recording", back_populates="recording_results", lazy="joined")

    speech_service_id = Column(Integer, ForeignKey('speech_services.id'), nullable=False)
    speech_service = relationship("SpeechService", back_populates="recording_results")

    created_at = Column(DateTime, nullable=False, default=func.now())
    updated_at = Column(DateTime, nullable=False,
                        default=func.now(), onupdate=func.now())
    deletedd_at = Column(DateTime, nullable=True)

    def __repr__(self):
        return 'id: {}'.format(self.id)

Recording.recording_results = relationship("RecordingResult", order_by=RecordingResult.id, back_populates="recording", lazy="joined")
SpeechService.recording_results = relationship("RecordingResult", order_by=RecordingResult.id, back_populates="speech_service")

我的架构：

class RecordingResultItemSchema(ma.Schema):
    class Meta:
        model = RecordingResult
        fields = ('id', 'is_with_dictionary', 'result', 'run_time', 'recording_id', 'speech_service_id')

class RecordingItemSchema(ma.Schema):
    class Meta:
        model = Recording
        fields = ('id', 'filepath', 'language_id', 'user_id', 'recording_results')  
    recording_results = ma.Nested(RecordingResultItemSchema)
recording_item_schema = RecordingItemSchema()
recording_items_schema = RecordingItemSchema(many=True)
recording_result_item_schema = RecordingResultItemSchema()
recording_result_items_schema = RecordingResultItemSchema(many=True)

Recording模型有很多RecordingResult（外键为recording_id）

我在 API 中使用了这个查询，使用 sqlalchemy 的“lazy”来获取 2 个模型的连接数据：

@app.route('/recording', methods=['GET'])
def get_recording_item():
    if db.session.query(Recording).options(joinedload(Recording.recording_results)).all():
        recording_list = db.session.query(Recording).options(joinedload(Recording.recording_results)).all()
        result = recording_items_schema.dump(recording_list)
        return jsonify(result.data), 200
    else:
        return jsonify(msg="Object not found"), 400

通过邮递员发送请求后，我收到了错误消息：

AttributeError：“recording_id”不是有效字段对于 [id: 1]。 // Werkzeug 调试器

在控制台中我得到了这个错误：

'"{0}" 不是 {1} 的有效字段。'.format(key, obj)) app_1
| AttributeError: "recording_id" 不是 [id: 1] 的有效字段。

我打印了查询并得到了结果，但是当我尝试使用模式时，这些字段似乎无效。我按照 flask-marshmallow 的文档使用嵌套对象，我做错了什么？任何帮助将不胜感激

【问题讨论】：

标签： python flask nested schema marshmallow

【解决方案1】：

我将架构更改为：

class RecordingResultItemSchema(ma.Schema):
    class Meta:
        model = RecordingResult
        fields = ('id', 'is_with_dictionary', 'result', 'run_time', 'recording_id', 'speech_service_id')

class RecordingItemSchema(ma.Schema):
    class Meta:
        model = Recording
        fields = ('id', 'filepath', 'language_id', 'user_id', 'recording_results')  
    recording_results = ma.Nested(RecordingResultItemSchema, many=True)

现在它起作用了，因为我没有将 many=True 参数放入

【讨论】：