I have a single-table inheritance setup:
class Device(Base):
__tablename__ = 'devices'
devtype = Column(Unicode(20), nullable = False)
mac = Column(Unicode(128), primary_key = True)
...
class PC(Device):
__mapper_args_ = {'polymorphic_identity':u'PC'}
switch_mac = Column(Unicode(128), ForeignKey(mac), nullable = True) #
ignore any typos here - this is munged code
class Switch(Device):
__mapper_args_ = {'polymorphic_identity':u'Switch'}
...
pc_ct_subq = select([func.count(PC.mac)]).where(PC.switch_mac ==
Switch.mac).as_scalar()
Switch.pc_ct = column_property(pc_ct_subq)
When I didn't have the inheritance set up (when Switch and PC were separate
tables and separate objects), pc_ct worked fine. Now, however, it's failing
- I think because the inheritance is appending "AND devices.devtype IN 'AP'"
to the initial load query since it's trying to bring up just devices of type
'Switch'.
How do I get around this? I just want Switch to have an attribute that
represents the number of PCs that are associated to it (where the PC's
switch_mac equals the Switch's mac).
Thanks,
S.
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