Hi,
i saw the example for the above in the:
http://permalink.gmane.org/gmane.comp.python.sqlalchemy.user/3713
but after several trials to map the tables did not succeed.
The example code below demonstrates the problem - I create 2 objects
that are interconnected and sqlalchemy generates insert for each
object. I suppose it must generate 2 inserts and after that one update.
Can somebody help me in properly mapping the tables?
my example code is:
from sqlalchemy import *
db = create_engine( 'sqlite:///:memory:')
meta = BoundMetaData( db)
meta.engine.echo = False
#==================== tables
t1 = Table('table1', meta,
Column('name', Integer, ),
Column('id', Integer, primary_key=True),
Column('t2_id', Integer,
ForeignKey('table2.id',
use_alter=True,
name='zt1id_fk'
)
)
)
t2 = Table('table2', meta,
Column('data', Integer, ),
Column('id', Integer, primary_key=True),
Column('t1_id', Integer,
ForeignKey('table1.id',
use_alter=True,
name='zt2id_fk'
)
)
)
meta.create_all()
#==================== mapping
class T1( object):
def __str__( self): return '%s: %s %s %s' %
(self.__class__.__name__, self.id, self.name, self.t
class T2( object):
def __str__( self): return '%s: %s %s %s' %
(self.__class__.__name__, self.id, self.data, self.t
mapper( T1, t1).add_property( 'tt2',
relation( T2, uselist=False, lazy=False,
# secondary=t2,
# secondaryjoin= t1.c.t2_id==t2.c.id,
primaryjoin= t2.c.t1_id==t1.c.id,
# secondaryjoin= t2.c.t1_id==t1.c.id,
# primaryjoin= t1.c.t2_id==t2.c.id,
# cascade='all',
backref=backref( 'tt1', cascade='all', use_list=False,)
) )
mapper( T2, t2).add_property( 'tt1',
relation( T1, uselist=False, lazy=False,
secondary=t1,
secondaryjoin= t2.c.t1_id==t1.c.id,
primaryjoin= t1.c.t2_id==t2.c.id,
# secondaryjoin= t1.c.t2_id==t2.c.id,
# primaryjoin = t2.c.t1_id==t1.c.id,
backref=backref( 'tt2', cascade='all', use_list=False,)
) )
#=================== example
session = create_session()
q = T1()
q.name = 't1name'
p = T2()
p.data = 't2data'
p.tt1 = q
q.tt2 = p
session.save(p)
session.flush()
SEP = 5*'-'
print 'before:', SEP, p, SEP, q
session.clear()
r = session.query( T1).get_by_id( p.id)
s = session.query( T2).get_by_id( q.id)
print 'after:', SEP, r, SEP, s
#eof
Thanks in advance
StefanB
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