Hi everyone, I am hitting an error while defining a relationship with a
parent table with a composite primary key (my child class has two
attributes that point to the same parent class -with a composite pk- but
both relationships are properly defined with the 'foreign_keys'
parameter): I am not sure the reason I get an AmbiguousForeignKeysError,
I have followed the docs and tried several alternatives to no avail.
Probably some typo or a silly mistake like that but I am unable to see
it. I would appreciate a pointer.
first, here is the error message I am getting:
File
"/home/mariano/Code/n-p/env/lib/python3.3/site-packages/SQLAlchemy-0.9.2-py3.3-linux-i686.egg/sqlalchemy/orm/relationships.py",
line 1868, in _determine_joins
% self.prop)
sqlalchemy.exc.AmbiguousForeignKeysError: Could not determine join
condition between parent/child tables on relationship Bet.runner - there
are multiple foreign key paths linking the tables. Specify the
'foreign_keys' argument, providing a list of those columns which should
be counted as containing a foreign key reference to the parent table.
and here is a completed self contained example to reproduce the problem:
from sqlalchemy import (
Table, Column, ForeignKey, Index, CheckConstraint,
ForeignKeyConstraint,
Integer, Text, String, Boolean, Date, Enum, Numeric,
inspect, create_engine,
and_
)
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import (
scoped_session,
sessionmaker,
relationship
)
DBSession = scoped_session(sessionmaker())
Base = declarative_base()
class User(Base):
__tablename__ = "user"
uid = Column(String(600), primary_key=True)
oid = Column(String(100), primary_key=True)
name = Column(String(600), nullable=False)
lastname = Column(String(600), nullable=False)
class Bet(Base):
__tablename__ = "bet"
__table_args__ = (
ForeignKeyConstraint(("uid", "oid"), ("user.uid", "user.oid")),
ForeignKeyConstraint(("loader_uid", "oid"), ("user.uid",
"user.oid")),
)
id = Column(Integer, autoincrement=True, primary_key=True)
uid = Column(String(600), nullable=False)
oid = Column(String(100), nullable=False)
number = Column(Integer, CheckConstraint("number<10000"))
loader_uid = Column(String(600), nullable=False)
# relationships
runner = relationship("User", foreign_keys=[uid, oid],
#primaryjoin=and_("Bet.uid==User.uid",
"Bet.oid==User.oid"),
)
loader = relationship("User", foreign_keys=[loader_uid, oid])
Index("runner_idx", Bet.__table__.c.uid, Bet.__table__.c.oid)
if __name__ == "__main__":
engine = create_engine('sqlite://')
DBSession.configure(bind=engine)
Base.metadata.create_all(engine)
u1 = User(uid='example1', oid='MDQ', name='Mariano', lastname='Mara')
u2 = User(uid='example2', oid='MDQ', name='Mariano', lastname='Mara')
DBSession.add_all([u1, u2])
DBSession.flush()
b = Bet(uid='example1', oid='MDQ', number=20, loader_uid='example2')
DBSession.add(b)
DBSession.commit()
Thanks in advance
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