SQLAlchemy 中的多个连接经常失败 'sqlalchemy.exc.ArgumentError'

Question

我不确定如何使用 SQLalchemy 正确地进行多重连接。

我正在尝试从 get 请求中获得一个结果，该结果提供了一个叙述列表 NarrativeModel，其中包含一个或多个引用 ReferenceModel，其中 publishDate 是一个给定值.在下面的示例中，这是 2022-03-09

但是，我不知道如何在 Narrative、NarrativeReference 和 Reference 之间执行联接。我的尝试大多以以下或类似结尾：sqlalchemy.exc.ArgumentError: SQL expression object expected, got object of type <class 'flask_sqlalchemy.model.DefaultMeta'> instead

叙事模型

class NarrativeModel(db.Model):
    __tablename__ = "narrative"

    id = db.Column(db.Integer, primary_key=True)
    title = db.Column(db.String, nullable=False)
    date = db.Column(db.String, nullable=True)
    ownerProfileID = db.Column(db.Integer, db.ForeignKey('profile.id'), nullable=False)
    scheduled = db.Column(db.Integer, nullable=True)
    ongoing = db.Column(db.Integer, nullable=True)

NarrativeReference 模型（加入table）

class NarrativeReferenceModel(db.Model):
    __tablename__ = "narrativereference"

    id = db.Column(db.Integer, primary_key=True)
    narrativeID = db.Column(db.Integer, db.ForeignKey('narrative.id'), nullable=False)
    referenceID = db.Column(db.Integer, db.ForeignKey('reference.id'), nullable=False)

参考模型

class ReferenceModel(db.Model):
    __tablename__ = "reference"

    id = db.Column(db.Integer, primary_key=True)
    langCode= db.Column(db.String, nullable=True)
    isGov = db.Column(db.String, nullable=True)
    type = db.Column(db.String, nullable=True)
    title = db.Column(db.String, nullable=True)
    domain = db.Column(db.String, nullable=True)
    suffix = db.Column(db.String, nullable=True)
    description = db.Column(db.String, nullable=True)
    publishDate = db.Column(db.String, nullable=True)
    addedDate = db.Column(db.String, nullable=True)
    url = db.Column(db.String, nullable=False)
    youtubeId = db.Column(db.String, nullable=True)
    langCheck = db.Column(db.Integer, nullable=True)

获取请求

class GlobalNarrativesByTodaysUpdates (Resource):

    #RETURNS ALL AVAILABLE NARRATIVES
    # Called with: curl --header "Content-Type: application/json" --request GET http://localhost:8080/narratives
    def get(self):
        schema = NarrativeSchema()
        result = NarrativeModel.query\
                .join(NarrativeReferenceModel, NarrativeModel.id == NarrativeReferenceModel.narrativeID)\
                .filter(ReferenceModel, ReferenceModel.publishDate == '2022-03-09').all()


        db.session.close()
        return schema.dump(result, many=True), 200

满足我需求的有效 SQL 语句是：

select distinct narrative.title, narrative.date from narrative, narrativereference
where narrativereference.narrativeID = narrative.id
and narrativereference.referenceID in (select id from reference where publishDate = '2022-03-09')

Answer 1

由于关系已在模型中定义，因此使用简单连接修复了它

    def get(self):
        schema = NarrativeSchema()
        result = NarrativeModel.query\
            .join(NarrativeReferenceModel)\
            .join(ReferenceModel)\
            .filter(ReferenceModel.addedDate == '2022-03-09').all()

        db.session.close()
        return schema.dump(result, many=True), 200

SQLAlchemy 中的多个连接经常失败 'sqlalchemy.exc.ArgumentError'

Multiple joins in SQLAlchemy often fails with 'sqlalchemy.exc.ArgumentError'

python

sql

sqlalchemy

叙事模型

NarrativeReference 模型（加入table）

参考模型

获取请求