Re: [Sqlalchemy-tickets] [sqlalchemy] #2751: assocaition proxy support for scalar-targeted attributes

[sqlalchemy <mi...@zz...>]

#2751: assocaition proxy support for scalar-targeted attributes
------------------------------+----------------------------------
      Reporter:  zzzeek       |      Owner:  zzzeek
          Type:  defect       |     Status:  new
      Priority:  high         |  Milestone:  0.9.0
     Component:  ext          |   Severity:  minor - half an hour
    Resolution:               |   Keywords:
Progress State:  in progress  |
------------------------------+----------------------------------
Description changed by zzzeek:

Old description:

> {{{
> #!python
> from sqlalchemy.engine import create_engine
> from sqlalchemy.ext.associationproxy import association_proxy
> from sqlalchemy.ext.declarative.api import declarative_base
> from sqlalchemy.orm import relationship
> from sqlalchemy.orm.session import sessionmaker
> from sqlalchemy.schema import Column, ForeignKey
> from sqlalchemy.types import Integer, String
>
> Base = declarative_base()
>
> class A(Base):
>     __tablename__ = 'table_a'
>     id = Column(Integer, primary_key=True)
>     color = Column(String)
>     def __init__(self, color):
>         self.color = color
>
> class B(Base):
>     __tablename__ = 'table_b'
>     id = Column(Integer, primary_key=True)
>     a_id = Column(Integer, ForeignKey('table_a.id'))
>     a_re = relationship('A', backref='b_re')
>     a_color = association_proxy('a_re', 'color')
>

> if __name__ == '__main__':
>     engine = create_engine('sqlite:///:memory:', echo=True)
>     Session = sessionmaker(engine)
>     session = Session()
>     Base.metadata.create_all(engine)
>
>     b1 = B()
>     b2 = B()
>     b3 = B()
>     b4 = B()
>
>     b1.a_color = 'blue'
>     b2.a_re = A(color=None)
>
>     session.add_all([b1, b2, b3, b4])
>
>     q = session.query(B).filter(B.a_color == None).all()
>     p = session.query(B).filter(B.a_color != None).all()
>
>     from sqlalchemy import __version__
>     if __version__ >= "0.9.0":
>
>         assert q == [b2, b3, b4]
>         assert p == [b1]
>
>         # will also add a special feature for this
>         r = session.query(B).filter(B.a_color.has()).all()
>         assert r == [b1, b2]
>
>         # this is the equivalent of 0.8's B.a_color != None
>         s = session.query(B).filter(
>                         or_(B.a_color != None,
>                             ~B.a_color.has())
>                     ).all()
>         assert s == [b1, b3, b4]
>     else:
>         assert q == [b2]
>         assert p == [b1, b3, b4]
> }}}
>
> this involves a behavioral change even to non-scalar association proxies,
> unless we special case it.   If we have
> Parent.m2o_something.m2o_otherthing / Parent.other, the meaning of
> `Parent.other == None` normally includes just
> `Parent.m2o_something.has(m2o_otherthing=None)` - this adds in
> `~Parent.m2o_something.has()`.
>
> As the example illustrates, this totally changes return results so
> there's a very high chance applications are relying on the current
> behavior, and am leaning towards an 0.9 only here.

New description:

 {{{
 #!python
 from sqlalchemy.engine import create_engine
 from sqlalchemy.ext.associationproxy import association_proxy
 from sqlalchemy.ext.declarative.api import declarative_base
 from sqlalchemy.orm import relationship
 from sqlalchemy.orm.session import sessionmaker
 from sqlalchemy.schema import Column, ForeignKey
 from sqlalchemy.types import Integer, String

 Base = declarative_base()

 class A(Base):
     __tablename__ = 'table_a'
     id = Column(Integer, primary_key=True)
     color = Column(String)
     def __init__(self, color):
         self.color = color

 class B(Base):
     __tablename__ = 'table_b'
     id = Column(Integer, primary_key=True)
     a_id = Column(Integer, ForeignKey('table_a.id'))
     a_re = relationship('A', backref='b_re')
     a_color = association_proxy('a_re', 'color')


 if __name__ == '__main__':
     engine = create_engine('sqlite:///:memory:', echo=True)
     Session = sessionmaker(engine)
     session = Session()
     Base.metadata.create_all(engine)

     b1 = B()
     b2 = B()
     b3 = B()
     b4 = B()

     b1.a_color = 'blue'
     b2.a_re = A(color=None)

     session.add_all([b1, b2, b3, b4])

     q = session.query(B).filter(B.a_color == None).all()
     p = session.query(B).filter(B.a_color != None).all()
     v = session.query(B).filter(B.a_color == 'blue').all()

     from sqlalchemy import __version__
     if __version__ >= "0.9.0":

         assert v == [b1]
         assert q == [b2, b3, b4]
         assert p == [b1]

         # will also add a special feature for this
         r = session.query(B).filter(B.a_color.has()).all()
         assert r == [b1, b2]

         # will also add a special feature for this
         w = session.query(B).filter(~B.a_color.has()).all()
         assert w == [b3, b4]

         # this is the equivalent of 0.8's B.a_color != None
         s = session.query(B).filter(
                         or_(B.a_color != None,
                             ~B.a_color.has())
                     ).all()
         assert s == [b1, b3, b4]
     else:
         assert v == [b1]
         assert q == [b2]
         assert p == [b1, b3, b4]
 }}}

 this involves a behavioral change even to non-scalar association proxies,
 unless we special case it.   If we have
 Parent.m2o_something.m2o_otherthing / Parent.other, the meaning of
 `Parent.other == None` normally includes just
 `Parent.m2o_something.has(m2o_otherthing=None)` - this adds in
 `~Parent.m2o_something.has()`.

 As the example illustrates, this totally changes return results so there's
 a very high chance applications are relying on the current behavior, and
 am leaning towards an 0.9 only here.

--

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Ticket URL: <http://www.sqlalchemy.org/trac/ticket/2751#comment:2>
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