Not working with sqlalchemy 1.1.15 and attrs 17.3.0

[chrisnorman7]

Hi,
Been using (and loving) attrs_sqlalchemy for a large VR project and it's recently stopped working after I updated to the latest sqlalchemy (version above).

Here's proof-of-concept code with the traceback:

from sqlalchemy import Column, Integer, String, create_engine
from sqlalchemy.ext.declarative import declarative_base
from attrs_sqlalchemy import attrs_sqlalchemy

engine = create_engine('sqlite:///:memory:')


class _Base:
    id = Column(Integer, primary_key=True)


Base = declarative_base(bind=engine, cls=_Base)


@attrs_sqlalchemy
class Object(Base):
    __tablename__ = 'objects'
    name = Column(String(50), nullable=True)


Base.metadata.create_all()


o = Object()
print(repr(o))

And here's the TB:

Traceback (most recent call last):
  File "test.py", line 25, in <module>
    print(repr(o))
  File "c:\Users\chris\envs\mindspace-server\lib\site-packages\attr\_make.py", line 814, in repr_
    for name in attr_names
  File "c:\Users\chris\envs\mindspace-server\lib\site-packages\attr\_make.py", line 814, in <genexpr>
    for name in attr_names
AttributeError: 'Object' object has no attribute 'name'

I'd be happy to go and try and affect a fix but I have no idea how. I'm going to start reading through your code and I will do my best to sort it myself. Do you have any pointers that might aid me in this? Of course if you fix it first that would be awesome! :-)

Cheers,

Chris

[adorack]

I ran into this same problem... it looks like it's due to a breaking change in the attrs package: python-attrs/attrs#253

SQLAlchemy's declarative mode relies on setting class attributes to represent columns. When attrs >= 17.3.0 processes the class, I think it's stripping out those attributes and replacing them with some other mechanism. This results in the AttributeError that you encountered above.

Unfortunately, I don't know enough about the inner workings of attrs to propose a fix -- for now, I'm working around the issue by just pinning the attrs version to 17.2.0.

[mjdunn]

If it helps anybody, I just submitted a pull request to restore support for attrs 17.3+: #13

Also, note that my PR is on the hash-by-id branch, so you should also review #10 and #11, which have their own breaking change you may care about.

[rouge8]

Hi all, we're going ahead and deprecating attrs_sqlalchemy and do not recommend using it going foward (#14).