Pydantic list of models with the same name

Question

Let's say I want to have a User model which also contains "friends" field which has to be a list of users:

class User(BaseModel):
    id: int
    name: str
    friends: List[User]

but it's not possible. Is there a way to achieve this behavior?

Answer 1

Yes you need to use update_forward_refs , see self-referencing models in the docs.

from typing import List

from devtools import debug

from pydantic import BaseModel


class User(BaseModel):
    id: int
    name: str
    friends: List['User']


User.update_forward_refs()

u = User(id=123, name='hello', friends=[dict(id=321, name='goodbye', friends=[])])

debug(u)

outputs:

test.py:18 <module>
    u: User(
        id=123,
        name='hello',
        friends=[
            User(
                id=321,
                name='goodbye',
                friends=[],
            ),
        ],
    ) (User)