Accessing AssociationProxy of aliased model breaks it

[sqlalchemy-bot]

Migrated issue, originally created by Dmytro Starosud (@dima-starosud)

This is using sqlalchemy 1.2.0b3.

When AssociationProxy is first accessed on aliased it leads to setting owning_class to that AliasedClass, which then leads to exceptions inside lib.
Please see details in following code snippet.

        class A(Base):
            __tablename__ = 'a'
            id = Column(Integer, primary_key=True)
            value = Column(String)

        class B(Base):
            __tablename__ = 'b'
            id = Column(Integer, primary_key=True)
            a_id = Column(Integer, ForeignKey(A.id))
            a = relationship(A)
            a_value = association_proxy('a', 'value')

        print(aliased(B).a_value)  # Due to this call line below fails
        print(B(a=A(value=4)).a_value)  # Class object expected, got '<AliasedClass at 0x7f491cbb3048; B>'.

Probably mapper should access AssociationProxy immediately after it's added to the model to trigger owning_class initialization.

[sqlalchemy-bot]

Changes by Dmytro Starosud (@dima-starosud):

• edited description

[sqlalchemy-bot]

Changes by Dmytro Starosud (@dima-starosud):

• edited description

[sqlalchemy-bot]

Michael Bayer (@zzzeek) wrote:

Probably mapper should access AssociationProxy immediately after it's added to the model to trigger owning_class initialization.

that would be very complicated. I will make it resolve the alias to the real class.

[sqlalchemy-bot]

Michael Bayer (@zzzeek) wrote:

https://gerrit.sqlalchemy.org/#/q/I9161bab67766bb75d73ca54d712ad1cad6de40dc

[sqlalchemy-bot]

Changes by Michael Bayer (@zzzeek):

• added labels: ext

[sqlalchemy-bot]

Changes by Michael Bayer (@zzzeek):

• set milestone to "1.1.x"

[sqlalchemy-bot]

Dmytro Starosud (@dima-starosud) wrote:

Thanks @zzzeek

Does Milestone 1.1.x mean we will see this in a version prior to 1.2.0 ?

[sqlalchemy-bot]

Michael Bayer (@zzzeek) wrote:

it means I'm cherry-picking it to the 1.1 branch as well which you can see in the above linked gerrit. So the next 1.1 release would also include it.

[sqlalchemy-bot]

Michael Bayer (@zzzeek) wrote:

Resolve AliasedClass when determining owning class of association proxy

Fixed bug where the association proxy would inadvertently link itself
to an :class:.AliasedClass object if it were called first with
the :class:.AliasedClass as a parent, causing errors upon subsequent
usage.

Change-Id: I9161bab67766bb75d73ca54d712ad1cad6de40dc
Fixes: #4116

→ f14a58d

[sqlalchemy-bot]

Michael Bayer (@zzzeek) wrote:

Resolve AliasedClass when determining owning class of association proxy

Fixed bug where the association proxy would inadvertently link itself
to an :class:.AliasedClass object if it were called first with
the :class:.AliasedClass as a parent, causing errors upon subsequent
usage.

Change-Id: I9161bab67766bb75d73ca54d712ad1cad6de40dc
Fixes: #4116
(cherry picked from commit f14a58d)

→ e111940

[sqlalchemy-bot]

Changes by Michael Bayer (@zzzeek):

• changed status to closed

[sqlalchemy-bot]

Dmytro Starosud (@dima-starosud) wrote:

Thanks @zzzeek !