On Fri, Jan 15, 2016 at 02:26:37PM +0100, Michal Petrucha wrote: > Hi Andreas, > > On Fri, Jan 15, 2016 at 02:56:39AM -0800, Andreas Jung wrote: > > Hi, > > > > I currently have the following mix-in class construction (based on the > > documentation > > http://docs.sqlalchemy.org/en/latest/orm/extensions/declarative/mixins.html > > ) > > > > Base = declarative_base() > > > > class BaseCountry(object): > > """ Managed through Kotti """ > > > > @declared_attr > > def __tablename__(cls): > > return cls.__name__.lower() > > > > dpis_id = Column(Integer, primary_key=True) > > title = Column(Unicode(80)) > > regions = relationship("Region", > > > > primaryjoin="Country.dpis_id==Region.country_id") > > As the error message in the exception says, this attribute needs to be > declared as a declared_attr, like this: > > @declared_attr > def regions(cls): > return relationship("Region", > primaryjoin="Country.dpis_id==Region.country_id")
...and just after I sent the email I realized this wouldn't work
either, because it hardcodes a fixed string as the originating table
name. Something like the following should work, though (according to
the docs I linked):
@declared_attr
def regions(cls):
return relationship("Region",
primaryjoin=lambda: cls.dpis_id == Region.country_id
)
...or perhaps this one, if you prefer:
@declared_attr
def regions(cls):
return relationship("Region",
primaryjoin="%s.dpis_id==Region.country_id" % cls.__name__
)
> This is stated in the following section of the docs:
> http://docs.sqlalchemy.org/en/latest/orm/extensions/declarative/mixins.html#mixing-in-relationships
>
> Good luck,
>
> Michal
>
> > "Mapper properties (i.e. deferred,"
> > sqlalchemy.exc.InvalidRequestError: Mapper properties (i.e.
> > deferred,column_property(), relationship(), etc.) must be declared as
> > @declared_attr callables on declarative mixin
> > classes.
>
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