Hi everyone, I'm getting in troubles doing some experiments with
sqlalchemy (0.6.3) orm. Here are two code snippets to show the
problems I'm encountering.
## map_1.py
engine = create_engine("mysql://user:passw...@localhost/mydb")
metadata = MetaData(engine)
parent_table = Table('parent', metadata,
Column('id', Integer, primary_key=True))
child_table = Table('child', metadata,
Column('id', Integer, primary_key=True),
Column('parent_id', Integer, ForeignKey('parent.id')))
metadata.create_all(engine)
engine.execute(parent_table.insert(), [{'id':1}, {'id':2}, {'id':3},
{'id':4}])
engine.execute(child_table.insert(), [{'parent_id':1}, {'parent_id':
2}, {'parent_id':2}, {'parent_id':2}])
## map_2.py
engine = create_engine("mysql://user:passw...@localhost/mydb")
metadata = MetaData(engine)
parent_table = Table("parent", metadata, autoload=True)
child_table = Table("child", metadata, autoload=True)
class Parent(object):
pass
class Child(object):
pass
mapper(Parent, parent_table, properties={'children':
relationship(Child)})
mapper(Child, child_table)
Session = sessionmaker()
Session.configure(bind=engine)
sess = Session()
res = sess.query(Parent).all()
print res[0].children
Everything works fine for map_1.py, but when I run map_2.py I get the
following error:
sqlalchemy.exc.ArgumentError: Could not determine join condition
between parent/child tables on relationship Parent.children. Specify
a 'primaryjoin' expression. If this is a many-to-many relationship,
'secondaryjoin' is needed as well.
Process terminated with an exit code of 1
Can anyone point me out what I am doing wrong? Thanks in advance!
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