自指关联关系SQLalchemy
自指关联关系SQLalchemy
提问于 2014-09-21 12:00:42
在我使用烧瓶-sqlalchemy的烧瓶应用程序中，我需要在两个联系人之间创建关联，这里是我的Contact模型。
class Contact(db.Model):
__tablename__ = 'contact'
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.Unicode(120), nullable=False, unique=False)
user_id = db.Column(db.Integer, db.ForeignKey('user.id'))
to_contacts = db.relationship('Contact',
secondary='ContactRelation',
primaryjoin='id==contactrelation.c.from_contact_id',
secondaryjoin='id==contactrelation.c.to_contact_id',
backref='from_contacts')还有我的关联类ContactRelation
class ContactRelation(db.Model):
__tablename__ = 'contactrelation'
id = db.Column(db.Integer, primary_key=True)
from_contact_id = db.Column(db.Integer, db.ForeignKey('contact.id'))
to_contact_id = db.Column(db.Integer, db.ForeignKey('contact.id'))
relation_type = db.Column(db.String(100), nullable=True)我有错误：
AttributeError: type object 'ContactRelation' has no attribute 'c'回答 4
Stack Overflow用户
回答已采纳
发布于 2014-09-29 06:53:01
感谢SQLAlchemy邮件列表上的米歇尔和西蒙，我需要association_proxy和两个联系关系。
class Contact(db.Model):
__tablename__ = 'contact'
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.Unicode(120), nullable=False, unique=False)
created_on = db.Column(db.DateTime, default=datetime.utcnow)
birthday = db.Column(db.DateTime)
background = db.Column(db.Text)
photo = db.Column(db.Unicode(120))
user_id = db.Column(db.Integer, db.ForeignKey('user.id'))
to_contacts = association_proxy('to_relations', 'to_contact')
from_contacts = association_proxy('from_relations', 'from_contact')
class ContactRelation(db.Model):
__tablename__ = 'contactrelation'
id = db.Column(db.Integer, primary_key=True)
from_contact_id = db.Column(db.Integer, db.ForeignKey('contact.id'))
to_contact_id = db.Column(db.Integer, db.ForeignKey('contact.id'))
relation_type = db.Column(db.String(100), nullable=True)
from_contact = db.relationship(Contact,
primaryjoin=(from_contact_id == Contact.id),
backref='to_relations')
to_contact = db.relationship(Contact,
primaryjoin=(to_contact_id == Contact.id),
backref='from_relations')Stack Overflow用户
发布于 2020-06-09 11:13:19
与关联对象的自引用多到多关系。
用户类别：
class User(Base):
__tablename__ = "User"
id = Column(String(36), primary_key=True, default=lambda : str(uuid1()))协会班：
class UserIgnore(Base):
__tablename__ = "UserIgnore"
id = Column(String(36), primary_key=True, default=lambda : str(uuid1()))
ignored_by_id = Column("ignored_by_id", String(36), ForeignKey("User.id"), primary_key=True)
ignored_by = relationship("User", backref="ignored_list", primaryjoin=(User.id == ignored_by_id))
ignored_id = Column("ignored_id", String(36), ForeignKey("User.id"), primary_key=True)
ignored = relationship("User", backref="ignored_by_list", primaryjoin=(User.id == ignored_id))访问关系对象。
someUser.ignored_list或
someUser.ignored_by_list多亏了肖恩
Stack Overflow用户
发布于 2014-09-21 15:12:32
你们的关系设计得不对。辅助类应该是普通表，而不是映射类。如果您希望在您的relation_type上获得额外的数据( ContactRelation )，您应该使用SQLAlchemy Relationship docs：relationships.html#association-object中描述的关联表模式
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原文链接：
https://stackoverflow.com/questions/25958963
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