How to pass a SQLAlchemy ORM model to Python Generic[T] class

Question

I'm trying to create an entity architecture with SQLAlchemy and python Generics, i.e Model -> Repository -> API

I have the following User model:

class User(db.Model):
  id
  username
  email
  ...

The following Repository code:

class UserRepository(Repository[User]):
  pass

I'm trying to find a way that I could "access" the User model from within the Repository base class, something like:

T = TypeVar('T')

class Repository(Generic[T]):

  @staticmethod
  def get(id) -> T:
    return T.query.filter(...)

Tried also going via db.session.query(...) without success.

Any ideas?

Thanks.

Ragnarok · Accepted Answer · 2021-12-17 12:45:37Z

2

Managed to solve it with the help of class variables

class XRepository(BaseRepository):
  model = X


class YRepository(BaseRepository):
  model = Y

class BaseRepository:

  @classmethod
  def get(cls):
    return cls.model.query.filter(...)

answered Dec 17, 2021 at 12:45

Ragnarok

17015 bronze badges

Sign up to request clarification or add additional context in comments.

1 Answer 1