I'm having trouble with SQLAlchemy throwing the warning "Unmanaged access of declarative attribute" when I try and inherit `__table_args__` with declarative.
I've been through the docs here: http://docs.sqlalchemy.org/en/latest/orm/extensions/declarative/mixins.html#combining-table-mapper-arguments-from-multiple-mixins ... but the examples provided do not include a base class whose `__table_args__` can be simply inherited (ie: used as-is without needing to redefine `__table_args__` in the subclass). I've been through the code and see why the warning is thrown (the class doesn't have a `_sa_class_manager` property bolted on yet), but I can't tell if this is something I can just ignore or not. It currently seems like it can't be ignored since I'm having some weird problems around this code (still under investigation), but I'd like to know if there is some way to safely prevent this warning while achieving the desired inheritance. If it *is* actually ignorable, I've gone as far as considering temporarily hacking on a `_sa_class_manager` property to suppress the warning, but yuck. Below is a small example of what I'm talking about. The `_BaseTableSetup_MIXIN` class sets up some common table definitions. Foo and Bar use them outright via simple inheritance. Baz tries to extend the `__table_args__`, but runs into the warning when accessing `__table_args__` on the parent mixin. Am I doing something wrong? How can this be done properly? Is ignoring the warning a bad idea? ### # sample code class _BaseTableSetup_MIXIN(object): a = Column(Integer) @declared_attr # so subclasses def __table_args__(cls): # all derived classes/tables must have the unique constraint (but should # also be free to add more) return (UniqueConstraint("a"), ) class Foo(ORMBase, _BaseTableSetup_MIXIN): # This class defines no extra __table_args b = Column(Integer) class Bar(ORMBase, _BaseTableSetup_MIXIN): # This class also defines no extra __table_args c = Column(Integer) class Baz(ORMBase, _BaseTableSetup_MIXIN): # This class needs the full base setup, plus additional __table_args__ d = Column(Integer) @declared_attr def __table_args__(cls): ret = list(_BaseTableSetup_MIXIN.__table_args__) # WARNING THROWN HERE! ret.append(UniqueConstraint("d")) return tuple(ret) ### -- SQLAlchemy - The Python SQL Toolkit and Object Relational Mapper http://www.sqlalchemy.org/ To post example code, please provide an MCVE: Minimal, Complete, and Verifiable Example. See http://stackoverflow.com/help/mcve for a full description. --- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at https://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
