如何使用flask和sqlalchemy在三个多对多模型中制作post数据

如何解决如何使用flask和sqlalchemy在三个多对多模型中制作post数据

我在三个表源类别和关键字之间的多对多关系概念中有三个模型：

class SourceDevice(db.Model):
    __tablename__ = "source_devices"

    id = db.Column(db.Integer,primary_key=True)
    source_id = db.Column(db.Integer,db.ForeignKey("sources.id"),nullable=False)
    categorie_id = db.Column(db.Integer,db.ForeignKey("categories.id"),nullable=False)
    keyword_id = db.Column(db.Integer,db.ForeignKey("keywords.id"),nullable=False)

    __table_args__ = (db.UniqueConstraint(source_id,categorie_id,keyword_id),)

    sources = db.relationship("Sources",back_populates="source_devices")
    categories = db.relationship("Categories",back_populates="source_devices")
    keywords = db.relationship("Keywords",back_populates="source_devices")

class Sources(db.Model,UserMixin):
    __tablename__ = "sources"
    
    id = db.Column(db.Integer,primary_key=True,autoincrement=True)
    source = db.Column(db.String(200),nullable=False)
    user_id = db.Column(db.Integer,db.ForeignKey('users.id'))
    #catgeorie_id =  db.Column(db.Integer,db.ForeignKey('categories.id'))
    date_created = db.Column(db.DateTime,default=datetime.utcNow)
    source_devices  = db.relationship('SourceDevice',back_populates='sources')
    #categories = db.relationship('Categories',secondary=categories_sources,lazy='subquery',#    backref=db.backref('pages',lazy=True))
    def serialize(self):
        return {'id': self.id,'source': self.source,'user_id': self.user_id,'date_created': self.date_created,}

class Categories(db.Model,UserMixin):
    __tablename__ = "categories"
    __table_args__ = {'extend_existing': True}
    id = db.Column(db.Integer,primary_key=True)
    category = db.Column(db.String(200),nullable=False)
    #source_id = db.Column(db.Integer,db.ForeignKey('sources.id'))
    date_created = db.Column(db.DateTime,default=datetime.utcNow)
    #keyword = db.relationship('Keywords',backref='categorie',lazy='dynamic')
    source_devices  = db.relationship('SourceDevice',back_populates='categories')
    def serialize(self):
        return {'id': self.id,'categorie': self.category,}


class Keywords(db.Model,UserMixin):
    __tablename__ = "keywords"
    
    id = db.Column(db.Integer,primary_key=True)
    keyword = db.Column(db.String(200),nullable=False)
    date_created = db.Column(db.DateTime,back_populates='keywords')

    def serialize(self):
        return {'id': self.id,'keyword': self.word,}

我发现这个链接很有帮助： Many-to-Many with three tables relating with each other (SqlAlchemy) 据我了解，我必须使用下面的代码根据现有来源和现有类别添加 ne 关键字：

categorie = db.session.query(Categories).filter(Categories.category == "Bricolage").first()
source = db.session.query(Sources).filter(Sources.source == "Amazon").first()
keyword = db.session.query(Keywords).filter(Keywords.keyword == "Marteau").first()
assoc = SourceDevice(sources=source,categories=categorie,keywords=keyword)
db.session.add(assoc)
db.session.commit()

但是如何仅根据来源添加类别而不必放置关键字。 如果我在模型中做错了，还请纠正我。

谢谢。

解决方法

您需要根据 class 字段在您的 Source 模型类中提供数据。

assoc =SourceDevice(source_id = source.id,categorie_id = categorie.id,keyword_id=keyword.id)

,

对于基于三个多对多概念中的来源的一个类别的解决方案：

categorie = db.session.query(Categories).filter(Categories.category == a given categoy).first()
source = db.session.query(Sources).filter(Sources.source == a given source ).first()

assoc = SourceDevice(sources=source,categories=categorie )
db.session.add(assoc)
db.session.commit()

确保将 SourceDevice 模型的 id_source、id_category 和 id_category 中的至少两个添加为可空。