Question

在SQLAlchemy文档中，有一个关于多对多关系的好例子。请参阅第二个代码块： http://docs.sqlalchemy.org/en/latest/orm/basic_relationships.html#many-to-many

我想做同样的事情，但是使用单个数据表，以便对象的父（s）和子（ren）属于同一类型。

我尝试的是这样的：

association_table = Table('association', Base.metadata,
    Column('left_id', Integer, ForeignKey('mytable.id')),
    Column('right_id', Integer, ForeignKey('mytable.id'))
)

class MyTable(Base):
    __tablename__ = 'mytable'
    id = Column(Integer, primary_key=True)
    children = relationship(
        "MyTable",
        secondary=association_table,
        back_populates="parents")
    parents = relationship(
        "MyTable",
        secondary=association_table,
        back_populates="children")

不幸的是，这会产生错误消息：

sqlalchemy.exc.AmbiguousForeignKeysError: Could not determine join condition between parent/child tables on relationship MyTable.children - there are multiple foreign key paths linking the tables via secondary table 'association'.  Specify the 'foreign_keys' argument, providing a list of those columns which should be counted as containing a foreign key reference from the secondary table to each of the parent and child tables.

我确实理解错误及其发生的原因，但我无法弄清楚，如何在SQLAlchemy中解决它。有人可以帮忙吗？感谢。

干杯，添

SQLAlchemy多对多只有一个数据表

0 个答案: