your RegEvent mapper is against the wrong table, here is the correct code:
from sqlalchemy import *
from sqlalchemy.orm import *
metadata = MetaData()
regevent = Table('regevent', metadata,
Column('id', Unicode(200), primary_key=True),
Column('author', Unicode(200), primary_key=True),
Column('since', DateTime),
Column('until', DateTime),
Column('title', Unicode(100)),
Column('content', Unicode(600)),
Column('status', Unicode(200)),
Column('published', DateTime))
class RegEvent(object):
pass
regevent_who = Table('regevent_who', metadata,
Column('id', Integer, primary_key=True,
autoincrement=True),
Column('regevent_id', Unicode(200)),
Column('regevent_author', Unicode(200)),
Column('email', Unicode(200)),
Column('status', Unicode(200)),
Column('role', Unicode(200)),
ForeignKeyConstraint(("regevent_id", "regevent_author"),
("regevent.id", "regevent.author"),
"regevent_fk"))
class RegEventWho(object):
pass
mapper(RegEvent, regevent, properties={
'who': relationship(RegEventWho)
})
mapper(RegEventWho, regevent_who)
print Session().query(RegEvent).join(RegEvent.who)
On Nov 30, 2010, at 12:22 PM, Mariano Mara wrote:
> Excerpts from Michael Bayer's message of Tue Nov 30 13:50:26 -0300 2010:
>> Nothing wrong with the mapping, except the "primaryjoin" is not needed.
>> The cause is certainly the usage of "useexisting", which implies that these
>> tables have already been created, and everything you are specifying in the
>> Table() is ignored. I wouldn't use that flag.
>>
>
> Thanks Michael as always.
>
> Removing the useexisting=True, if I also remove the primaryjoin I get:
>
> ArgumentError: Could not determine join condition between parent/child
> tables on relationship RegEvent.who. Specify a 'primaryjoin' expression. If
> 'secondary' is
> present, 'secondaryjoin' is needed as well.
>
> If I leave the primaryjoin I still get the same error as reported.
>
> TIA for any extra ideas you can suggest to fix this.
>
> Mariano
>
>> On Nov 30, 2010, at 10:22 AM, Mariano Mara wrote:
>>
>>> Hi.
>>>
>>> I'm trying to relate two tables with a one to many relationship (the
>>> parent table has a composite primary key) but I'm getting a mapper
>>> error. I found a recent message about this same problem but with
>>> declarative base (which I don't use) and not sure why the suggestion
>>> there didn't apply to my problem.
>>>
>>> Find below the error and the table creation code.
>>>
>>> TIA,
>>> Mariano
>>>
>>> Error:
>>>
>>> ArgumentError: Could not locate any equated, locally mapped column pairs
>>> for primaryjoin condition 'regevent.id =
>>> regevent_who.regevent_id AND regevent.author =
>>> regevent_who.regevent_author' on relationship RegEvent.who. For more
>>> relaxed rules on join conditions, the relationship may be marked as
>>> viewonly=True.
>>>
>>> Code:
>>>
>>> regevent = Table('regevent', metadata,
>>> Column('id', Unicode(200), primary_key=True),
>>> Column('author', Unicode(200), primary_key=True),
>>> Column('since', DateTime),
>>> Column('until', DateTime),
>>> Column('title', Unicode(100)),
>>> Column('content', Unicode(600)),
>>> Column('status', Unicode(200)),
>>> Column('published', DateTime),
>>> useexisting=True)
>>> Index('regevent_cal_ix', *(regevent.c.calname,))
>>>
>>> class RegEvent(object):
>>> pass
>>>
>>> regevent_who = Table('regevent_who', metadata,
>>> Column('id', Integer, primary_key=True,
>>> autoincrement=True),
>>> Column('regevent_id', Unicode(200)),
>>> Column('regevent_author', Unicode(200)),
>>> Column('email', Unicode(200)),
>>> Column('status', Unicode(200)),
>>> Column('role', Unicode(200)),
>>> ForeignKeyConstraint(("regevent_id", "regevent_author"),
>>> ("regevent.id", "regevent.author"),
>>> "regevent_fk"),
>>> useexisting=True)
>>> Index("regevent_who_fk_ix", *(regevent_who.c.regevent_id,
>>> regevent_who.c.regevent_author))
>>>
>>> class RegEventWho(object):
>>> pass
>>>
>>>
>>> mapper(RegEvent, regevent_who, properties={
>>> 'who': relationship(RegEventWho,
>>> primaryjoin=and_(
>>> regevent.c.id==regevent_who.c.regevent_id,
>>>
>>> regevent.c.author==regevent_who.c.regevent_author))
>>> })
>>> mapper(RegEventWho, regevent_who)
>>>
>>>
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>>
>
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