I tried to use sqlaclhemy joined table inheritance and had a strange occurrence.
class CommonObject(Base):
__tablename__ = "objects"
id = Column("objid", Integer, primary_key=True)
objname = Column(String(32))
...
class GoodsPlacement(Container, Loadable, Dumpable):
__tablename__ = "goods_placements"
id = Column("objid", Integer, ForeignKey("containers.objid"), primary_key=True)
...
class Departure(CommonObject):
__tablename__ = "departures"
id = Column(Integer, ForeignKey("objects.objid"), primary_key=True)
content_id = Column(Integer, ForeignKey("goods_placements.objid"))
content = relationship("GoodsPlacement",
primaryjoin="Departure.content_id==GoodsPlacement.id",
foreign_keys=[content_id],
lazy='joined',
backref="departures")
...
When I write query:
session.query(GoodsPlacement).filter(~GoodsPlacement.departures.any(Departure.status_id < 2))
it generates me something like this:
SELECT
objects.objid AS objects_objid,
goods_placements.objid AS goods_placements_objid,
objects.objname AS objects_objname
FROM objects
JOIN goods_placements ON objects.objid = goods_placements.objid
WHERE NOT (EXISTS (
SELECT 1
FROM (
SELECT
objects.objid AS objects_objid,
objects.objname AS objects_objname,
departures.id AS departures_id,
departures.content_id AS departures_content_id,
departures.status_id AS departures_status_id
FROM objects
JOIN departures ON objects.objid = departures.id)
AS anon_1, objects
WHERE anon_1.departures_content_id = objects.objid
AND anon_1.departures_status_id < :status_id_1)
)
And this doesn't work because objects in exist clause overrides outer objects. As workaround I used exists from sqlexpression directly,
session.query(GoodsPlacement).filter(~exists([1],
and_("departures.status_id<2",
"departures.content_id=goods_placements.objid"),
from_obj="departures"))
but it strongly depends from column and table names.
How I can specify alias for object table in exists statement?
Debian wheezy, python-2.7.3rc2, sqlaclhemy 0.7.7-1
there's a bug involving the declarative system in how it sets up columns. The "objid" name you're giving the columns, distinct from the "id" attribute name, is the source of the issue here. The below test case approximates your above system and shows a workaround until the bug is fixed:
output: