Ok, I translated my example to SQLAlchemy:
--------------------------------------
from sqlalchemy import *
from sqlalchemy.orm import mapper, relation, sessionmaker
engine = create_engine('sqlite:///:memory:', echo=True)
metadata = MetaData()
class A(object):
def __init__(self, name):
self.name = name
def __repr__(self):
return '<A: %r>' % self.name
class B(A):
def __init__(self, name):
super(B, self).__init__(name)
def __repr__(self):
return '<B: %r>' % self.name
class C(A):
def __init__(self, name):
super(C, self).__init__(name)
def __repr__(self):
return '<C: %r>' % self.name
_a_table = Table('a', metadata,
Column('id', Integer, primary_key=True),
Column('name', String),
Column('type', String(30), nullable=False)
)
_b_table = Table('b', metadata,
Column('id', Integer, ForeignKey('a.id'), primary_key=True)
)
_c_table = Table('c', metadata,
Column('id', Integer, ForeignKey('a.id'), primary_key=True),
Column('b_id', Integer, ForeignKey('b.id'))
)
mapper(A, _a_table, polymorphic_on=_a_table.c.type,
polymorphic_identity='a')
mapper(B, _b_table, inherits=A, polymorphic_identity='b', \
properties={'many_c': relation(C, backref='some_b', \
primaryjoin=_b_table.c.id==_c_table.c.b_id)})
mapper(C, _c_table, inherits=A, polymorphic_identity='c')
metadata.create_all(engine)
Session = sessionmaker(engine)
session = Session()
b = B(name='b')
session.save(b)
c1 = C(name='c1')
c2 = C(name='c2')
b.many_c.append(c1)
b.many_c.append(c2)
session.save(b)
print b
print b.many_c
for c in b.many_c:
print c.some_b
-----------------------------
I had to define the primaryjoin keyword to get this working.
So, how to use that with Elixir? How do I achieve the same?
Regards,
Ben
On Aug 29, 8:53 pm, "Gaetan de Menten" <[EMAIL PROTECTED]> wrote:
> On 8/29/07, Ben Schwarze <[EMAIL PROTECTED]> wrote:
>
>
>
>
>
> > Hi all,
>
> > I'm having a problem in using inheritance in combination with multiple
> > ForeignKeys.
>
> > --------------------------------------------
>
> > from elixir import *
>
> > metadata.bind = 'sqlite:///mydbname.sqlite'
>
> > class A(Entity):
> > has_field('name', String)
> > using_options(shortnames=True, inheritance='multi',
> > polymorphic=True)
>
> > class B(A):
> > has_many('many_c', of_kind='C', inverse='some_b')
> > using_options(shortnames=True, inheritance='multi',
> > polymorphic=True)
>
> > class C(A):
> > belongs_to('some_b', of_kind='B', inverse='many_c')
> > using_options(shortnames=True, inheritance='multi',
> > polymorphic=True)
>
> > create_all()
>
> > --------------------------------------
>
> > Executing this example it gives me the following error:
>
> > sqlalchemy.exceptions.ArgumentError: Can't determine join between
> > 'Join object on a b' and 'c'; tables have more than one foreign key
> > constraint relationship between them. Please specify the 'onclause' of
> > this join explicitly.
>
> > How can this problem be solved?
>
> This is obviously a bug in Elixir or SQLAlchemy. Unfortunately I have
> no time at the moment to track it down. If you want to help fixing it,
> the first step is to translate your example into raw SQLAlchemy code
> and see if that works or not.
>
> If it doesn't work, please report it to the SQLAlchemy's list.
> Otherwise, report back here, along with your SQLAlchemy code so that I
> can figure out what is Elixir doing differently.
> --
> Gaëtan de Mentenhttp://openhex.org
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