Sqlalchemy返回关系与使用marshmallow的嵌套联接
目前,我有一组表,它们之间建立了明确的关系。但是,我需要一个与答案表和问题表有关系的表(应用程序),以便只显示带有标记为活动的问题的答案。我试图通过应用程序模型来实现这一点,以便在棉花糖中它可以返回到应用程序内部。我还尝试在不生成N+1查询的情况下执行此操作 桌子Sqlalchemy返回关系与使用marshmallow的嵌套联接,sqlalchemy,flask-sqlalchemy,marshmallow,Sqlalchemy,Flask Sqlalchemy,Marshmallow,目前,我有一组表,它们之间建立了明确的关系。但是,我需要一个与答案表和问题表有关系的表(应用程序),以便只显示带有标记为活动的问题的答案。我试图通过应用程序模型来实现这一点,以便在棉花糖中它可以返回到应用程序内部。我还尝试在不生成N+1查询的情况下执行此操作 桌子 application_question_table = db.Table( 'application_questions', db.Column( 'application_id',
application_question_table = db.Table(
'application_questions',
db.Column(
'application_id',
db.Integer,
db.ForeignKey(
'application.id',
name="application_questions_application_id_fkey",
ondelete="CASCADE"
)
),
db.Column(
'question_id',
db.Integer,
db.ForeignKey(
'question.id',
name="application_questions_question_id_fkey",
ondelete="CASCADE"
)
)
)
class Application(Base):
id = db.Column(db.Integer, primary_key=True)
answers = db.relationship('Answer', back_populates="application", cascade=‘delete)
active_answers = db.relationship("should only show answerswhere question is active")
questions = db.relationship('Question', lazy="dynamic", secondary=application_question_table)
class Answer(Base):
id = db.Column(db.Integer, primary_key=True)
question_id = db.Column(db.Integer, db.ForeignKey('question.id', ondelete="SET NULL", name="answer_question_id_fkey"))
question = db.relationship('Question', back_populates=“answers")
class Question(Base):
id = db.Column(db.Integer, primary_key=True)
answers = db.relationship("Answer", back_populates="question")
applications = db.relationship('Application',lazy="dynamic", secondary=application_question_table)
active = db.Column(db.Boolean, default=True)
模式-请注意,GetVisible问题本质上就是我希望发生的事情。但我不喜欢这样做,因为这将是我找到的每个应用程序的附加查询
class ApplicationSchema(ModelSchema):
visible_answers = fields.Method('get_visible_answers')
class Meta:
model = Application
def get_visible_answers(self, application):
schema = ApplicationAnswerSchema(many=True)
answers = Answer.query.join(
Answer.application,
Answer.question
).filter(
Application.id == application.id,
Question.active == True,
).all()
return schema.dump(answers).data
class ApplicationAnswerSchema(ModelSchema):
class Meta:
model = Answer
我的预期行为是当我做类似的事情时
applications = Application.query.options(joinedload(Application.active_answers)).all()
schema = ApplicationSchema(many=True)
results = schema.dump(applications)
只有一个查询,我可以输入每个应用程序并获得可见的答案
我得到的实际结果是为每个应用程序发出一个额外的查询