I have a number of database that have the same tables in them.
I create a session for 1 data and do some work. This work causes
a number of table table object to be reflected from the database
and then mapped. This works fine.
Now I Switch to another database which has the same tables. If I
access only table that had been mapped in first database
things go fine. If I try to map a new table this is where
problems start with it not handling the relation. The
mapper when compiled says the following:
ArgumentError: Could not determine join condition between parent/child tables on
relation mds_ltc_mi.stx_setup. Specify a 'primaryjoin' expression. If this is
a many-to-many relation, 'secondaryjoin' is needed as well.
If I access the same table/mapped object in the first database thing
work just fine. It pickup the foreign keys and everything work just fine
All session are created as follows:
self._engine = create_engine(url,pool_recycle=14400, echo=debug)
self.metadata = MetaData()
self.metadata.bind = self._engine
self.session = Session(bind=self._engine, autoflush=False,
_enable_transaction_accounting=False, autocommit=True,
weak_identity_map=True)
Mapping code look like the following:
mapped_class = class_mapper(map_class, compile=False, raiseerror=False)
if mapped_class:
return mapped_class
if map_class.__table_name__ in self.metadata.tables:
table = self.metadata.tables[map_class.__table_name__]
else:
table = Table(name, self.metadata, autoload=True)
mapped_class = mapper(map_class, table, mapping_option)
mapped_class.compile()
return mapped_class
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