I can confirm this is a bug as I've found precedent for this not having to
raise, new issue is
https://github.com/sqlalchemy/sqlalchemy/issues/4997
On Fri, Nov 22, 2019, at 9:24 AM, Mike Bayer wrote:
> that said, I'm looking at this as a potential bug because it should be able
> to leave this attribute alone, not really sure how this should be handled.
>
> On Fri, Nov 22, 2019, at 9:21 AM, Mike Bayer wrote:
>> lazy="raise" on a many to one is problematic because a lot of many-to-one
>> operations involve pulling up the object from the identity map, and that's
>> it. since people are usually only trying to guard against SQL being emitted,
>> use the raise_on_sql option instead:
>>
>> parent = relationship(Parent, lazy='raise_on_sql')
>>
>> thanks for the perfect test case BTW makes this very easy for me
>>
>> On Fri, Nov 22, 2019, at 6:12 AM, Marat Sharafutdinov wrote:
>>> from sqlalchemy import Column, ForeignKey, Integer, create_engine
>>> from sqlalchemy.ext.declarative import declarative_base
>>> from sqlalchemy.orm import relationship, sessionmaker
>>>
>>> Base = declarative_base()
>>>
>>> class Parent(Base):
>>> __tablename__ = 'parents'
>>> id = Column(Integer, primary_key=True)
>>>
>>> class Child(Base):
>>> __tablename__ = 'children'
>>> id = Column(Integer, primary_key=True)
>>> parent_id = Column(Integer, ForeignKey(Parent.id))
>>> parent = relationship(Parent, lazy='raise', passive_deletes=True)
>>>
>>> engine = create_engine('sqlite:///:memory:', echo=True)
>>> Base.metadata.create_all(engine)
>>> Session = sessionmaker(bind=engine)
>>> session = Session()
>>>
>>> # Add
>>> parent = Parent()
>>> session.add(parent)
>>> session.flush()
>>> child = Child(parent_id=parent.id)
>>> session.add(child)
>>> session.commit()
>>>
>>> # Delete
>>> child = session.query(Child).first()
>>> session.delete(child)
>>> session.commit()
>>>
>>> Now I'm getting the following warning:
>>> /.venv/lib/python3.8/site-packages/sqlalchemy/orm/relationships.py:2021:
>>> SAWarning: On Child.parent, 'passive_deletes' is normally configured on
>>> one-to-many, one-to-one, many-to-many relationships only.
>>>
>>> If I change `parent` relationship as follows:
>>> parent = relationship(Parent, lazy='raise', backref=backref('children',
>>> passive_deletes=True))
>>> then I would get the following exception:
>>> sqlalchemy.exc.InvalidRequestError: 'Child.parent' is not available due to
>>> lazy='raise'
>>>
>>> How should it be made properly?
>>>
>>> --
>>> 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.
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>>
>>
>> --
>> 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.
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>
>
> --
> 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.
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>
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--
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.
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