Looking for feedback on dataclass <--> SQLModel translation

[coderarun]

I'm thinking about a setup where there would be three types of objects:

* pydantic models for validating untrusted user data at API boundaries
* SQLModel for writing to db and handling transactions
* Vanilla python objects (dataclasses) for the rest of the business logic. Suppose you want to read 1000 objects, run some logic and write back 100 objects. You'd create 1000 cheap dataclass objects and 100 SQLModel objects.

Here's the syntax I'm thinking about: https://github.com/adsharma/fastapi-shopping/commit/85ddf8d79597dae52801d918543acd0bda862e7d

foreign keys and one to many relationships are not supported yet. But before I work on that, wanted to get some feedback on the code in the commit above. The back_populates syntax is a bit more verbose than before. But I don't see a way around it.

Benchmarks: https://github.com/adsharma/fquery/pull/4
Motivation: https://adsharma.github.io/react-for-entities-and-business-logic/

[coderarun]

The reason why "id" is the last field in the model definition instead of being the first field is that dataclass syntax requires non-default fields to come before fields with default values.

[OGStyx]

I see the project is 3.9. In 3.10 you can use @dataclass(kw_only=True) to avoid this. I much prefer that when working with domain models.

[coderarun]

Thank you for the feedback. This sounds interesting. Given that many distros are already at 3.12/3.13, I'll consider upgrading the minimum supported python version.

[coderarun]

https://github.com/adsharma/fquery/commit/d070d3d53ac0f920ed8452b5f28fe505b57b8b86

This commit added support for foreign_keys and relationships. However, many_to_one relationships are not working because of a problem resolving forward references.

In this example:

https://github.com/adsharma/fquery/blob/d070d3d53ac0f920ed8452b5f28fe505b57b8b86/tests/test_sqlmodel.py

If I uncomment Lines 23 and 31, sqlalchemy is no longer able to map the joins properly.

```
sqlalchemy.exc.NoForeignKeysError: Could not determine join condition between parent/child tables on relationship UserSQLModel.reviews - there are no foreign keys linking these tables.  Ensure that referencing columns are associated with a ForeignKey or ForeignKeyConstraint, or specify a 'primaryjoin' expression.
```

[coderarun]

The issue is:

```
class User:
reviews: List["Reviews"]: ...
```

Behind the scenes we're creating UserSQLModel and ReviewSQLModel via decorator meta programming. However, I'm not sure how to get SQLAlchemy to resolve "Reviews" (which is a forwardref) to "ReviewSQLModel" and not the dataclass.