sqlmodel: SQLAlchemy version 1.4.36 breaks SQLModel relationships

First Check

  • I added a very descriptive title to this issue.
  • I used the GitHub search to find a similar issue and didn’t find it.
  • I searched the SQLModel documentation, with the integrated search.
  • I already searched in Google “How to X in SQLModel” and didn’t find any information.
  • I already read and followed all the tutorial in the docs and didn’t find an answer.
  • I already checked if it is not related to SQLModel but to Pydantic.
  • I already checked if it is not related to SQLModel but to SQLAlchemy.

👆 Not quite true - this is definitely related to SQLAlchemy!

Commit to Help

  • I commit to help with one of those options 👆

Example Code

from typing import Optional

from sqlmodel import Field, Relationship, SQLModel


class City(SQLModel, table=True):
    name: str = Field(primary_key=True)
    heroes: "Hero" = Relationship(back_populates="city")

class Hero(SQLModel, table=True):
    name: str = Field(primary_key=True)
    city_name: Optional[str] = Field(default=None,foreign_key="city.name")
    city: Optional[City] = Relationship(back_populates="heroes",
                              sa_relationship_kwargs=dict(cascade="all,delete")
                              )


if __name__ == "__main__":

    gotham = City(name="Gotham")
    batman = Hero(name="Batman", city=gotham)

    assert batman.name == 'Batman' # This is fine
    assert batman.city == gotham # This now breaks

Description

Our CI suddenly started failing, despite local SQLModel working fine. The issues turns out to be the transitive dependency on SQLAlchemy, which is weakly pinned: Github Actions pulled the latest version (1.4.36) and most of our tests started failing.

https://github.com/sqlalchemy/sqlalchemy/releases/tag/rel_1_4_36

The problem seems to be related to how relationships are defined, but I haven’t yet dug into the SQLAlchemy changes enough to understand why that is.

I’m opening this issue chiefly to help anybody else who is confused by why suddenly their tests are failing. I’m happy to help fix it if it’s affecting others too.

For the time being we have just pinned SQLAlchemy==1.4.34 in our requirements.txt.

Operating System

Linux, macOS

Operating System Details

Replicated locally and on Github Actions, both running in Docker

SQLModel Version

0.0.6

Python Version

3.9.10

Additional Context

We were previously running SQLAlchemy 1.4.34 locally and that works fine. Pinning to 1.4.36 breaks SQLModel.

About this issue

  • Original URL
  • State: closed
  • Created 2 years ago
  • Reactions: 66
  • Comments: 21 (7 by maintainers)

Commits related to this issue

Most upvoted comments

Thanks for the report @archydeberker! 🤓

And thanks for the discussion everyone! This was solved by @byrman in https://github.com/tiangolo/sqlmodel/pull/322.

It will be available in the next version, SQLModel 0.0.7, released in the next hours. 🚀

+18
tiangolo on Aug 27, 2022

The issue remains with SQLAlchemy version 1.4.37

+12
AlanSBPerkins on Jun 16, 2022

We pinned to 1.4.35, in our fork of sqlmodel. Happened to have that locally as upgraded recently and hadn’t had problems. Ran into this same this afternoon. Thanks for reporting!

+9
antont on Apr 27, 2022

Same issue here, pinning to 1.4.35 resolved

+8
JLHasson on Apr 27, 2022

Echoing that we are also seeing this issue in our project. Pinning to sqlalchemy==1.4.35 fixes the problem. All SQLAlchemy versions > 1.4.35 break relationships. @andersy005, I’ll make a note on our repo to follow this issue, and release the hard SQLAlchemy pin after this is resolved upstream.

+5
cisaacstern on Jul 24, 2022

For reference, the actual error message is:

AttributeError: 'SomeModelWithRelationshipAttribute' object has no attribute 'the_relationship_attribute'
+5
maresb on May 6, 2022

The SQLAlchemy maintainers confirmed that this is the issue, and also suggested a fix : https://github.com/sqlalchemy/sqlalchemy/discussions/7972#discussioncomment-2655517

+4
jossefaz on Apr 30, 2022

As @byrman wrote, the change of DeclarativeMeta seems to be the breaking change here.

[orm] [declarative] [bug] Modified the DeclarativeMeta metaclass to pass cls.dict into the declarative scanning process to look for attributes, rather than the separate dictionary passed to the type’s init() method. This allows user-defined base classes that add attributes within an init_subclass() to work as expected, as init_subclass() can only affect the cls.dict itself and not the other dictionary. This is technically a regression from 1.3 where dict was being used.

+3
jossefaz on Apr 28, 2022

It seems related to this recent change:

class DeclarativeMeta(
    _DynamicAttributesType, inspection.Inspectable["Mapper[Any]"]
):
    metadata: MetaData
    registry: "RegistryType"

    def __init__(
        cls, classname: Any, bases: Any, dict_: Any, **kw: Any
    ) -> None:
        # use cls.__dict__, which can be modified by an
        # __init_subclass__() method (#7900)
        dict_ = cls.__dict__  # This line is the culprit?!

https://github.com/sqlalchemy/sqlalchemy/blob/main/lib/sqlalchemy/orm/decl_api.py#L114

+3
byrman on Apr 28, 2022

#322 fix the issue for my use cases. Thanks @byrman

+2
GuiGarnier on May 25, 2022

@mathieu-lemay, I made a pull request that covers your case as well: https://github.com/tiangolo/sqlmodel/pull/461. I still have to add a test though.

+1
byrman on Oct 8, 2022

thank you @archydeberker !! after hours of debugging i found this issue pinned the version and it works now! ❤️ thank you!

+1
eddywee on May 18, 2022

Not sure if this is a sustainable fix, I don’t know how to leverage __init_subclass__, but adding 1 line after here makes things work again:

...
dict_used[rel_name] = rel_value
setattr(cls, rel_name, rel_value)  # Quick fix?
+1
byrman on Apr 28, 2022
Read more comments on GitHub
← sqlmodel: Optional[Dict[str, str]] field handle error, (sqlite3.InterfaceError) Error binding parameter 4 - probably unsupported type.
sqlmodel: SQLModel doesn't raise ValidationError →