set echo="debug" on your engine to see the rows coming back. as is,
the query from A returns:
Row (u'aaa', None, None, None, u'a', 1)
Row (u'aaa', u'ccc', u'bbb', None, u'c', 3)
Row (u'aaa', u'ccc', u'bbb', None, u'd', 4)
Row (u'aaa', None, u'bbb', None, u'b', 2)
Row (u'aaa', None, u'bbb', None, u'c', 3)
Row (u'aaa', None, u'bbb', None, u'd', 4)
Row (u'aaa', u'ccc', u'bbb', u'ddd', u'd', 4)
changing the poly unions to look like this fixes it:
abcd_union = polymorphic_union(
{
'd':a_table.join(b_table).join(c_table).join(d_table),
'c':a_table.join(b_table).join(c_table).select
(a_table.c.type=="c"),
'b':a_table.join(b_table).select(a_table.c.type=="b"),
'a':a_table.select(a_table.c.type=='a')
}, None)
someday ill be brave enough to build these poly unions into the core
engine...they have come a long way in recent months but i still feel
like we're still learning about their quirks (hence i force everyone
to learn about them :) ).
On Mar 7, 2007, at 3:01 PM, Mathieu Rouleau wrote:
> metadata = BoundMetaData('sqlite:///')
>
> class A(object):
> def __init__(self, a):
> self.a = a
> def __repr__(self):
> return '<A a=%s>' % self.a
>
> class B(A):
> def __init__(self, a, b):
> self.a = a
> self.b = b
> def __repr__(self):
> return '<B a=%s b=%s>' % (self.a, self.b)
>
> class C(B):
> def __init__(self, a, b, c):
> self.a = a
> self.b = b
> self.c = c
> def __repr__(self):
> return '<C a=%s b=%s c=%s>' % (self.a, self.b, self.c)
>
> class D(C):
> def __init__(self, a, b, c, d):
> self.a = a
> self.b = b
> self.c = c
> self.d = d
> def __repr__(self):
> return '<D a=%s b=%s c=%s d=%s>' % (self.a, self.b, self.c,
> self.d)
>
> a_table = Table('a_table', metadata,
> Column('id', Integer, primary_key=True),
> Column('a', String(32)),
> Column('type', String(30)))
>
> b_table = Table('b_table', metadata,
> Column('id', Integer, ForeignKey('a_table.id'),
> primary_key=True),
> Column('b', String(32)))
>
> c_table = Table('c_table', metadata,
> Column('id', Integer, ForeignKey('b_table.id'),
> primary_key=True),
> Column('c', String(32)))
>
> d_table = Table('d_table', metadata,
> Column('id', Integer, ForeignKey('c_table.id'),
> primary_key=True),
> Column('d', String(32)))
>
> abcd_union = polymorphic_union(
> {
> 'd':a_table.join(b_table).join(c_table).join(d_table),
> 'c':a_table.join(b_table).join(c_table),
> 'b':a_table.join(b_table),
> 'a':a_table.select(a_table.c.type=='a')
> }, None)
>
> bcd_union = polymorphic_union(
> {
> 'd':a_table.join(b_table).join(c_table).join(d_table),
> 'c':a_table.join(b_table).join(c_table),
> 'b':a_table.join(b_table),
> }, None)
>
> cd_union = polymorphic_union(
> {
> 'd':a_table.join(b_table).join(c_table).join(d_table),
> 'c':a_table.join(b_table).join(c_table),
> }, None)
>
> a_mapper = mapper(A, a_table, select_table=abcd_union,
> polymorphic_on=abcd_union.c.type, polymorphic_identity='a')
> b_mapper = mapper(B, b_table, select_table=bcd_union,
> inherits=a_mapper, polymorphic_on=bcd_union.c.type,
> polymorphic_identity='b')
> c_mapper = mapper(C, c_table, select_table=cd_union,
> inherits=b_mapper, polymorphic_on=cd_union.c.type,
> polymorphic_identity='c')
> mapper(D, d_table, inherits=c_mapper, polymorphic_identity='d')
>
> a_table.create()
> b_table.create()
> c_table.create()
> d_table.create()
>
> session = create_session()
> session.save(A(a='aaa'))
> session.save(B(a='aaa',b='bbb'))
> session.save(C(a='aaa',b='bbb',c='ccc'))
> session.save(D(a='aaa',b='bbb',c='ccc',d='ddd'))
> session.flush()
>
> #comment this clear for success
> session.clear()
>
> l = session.query(A).select()
> print l
>
> l = session.query(D).select()
> assert l[0].d == 'ddd'
>
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