Pydantic: Can I use LSP with pydantic?

[mcauto]

Question

Output of python -c "import pydantic.utils; print(pydantic.utils.version_info())":

             pydantic version: 1.6.1
            pydantic compiled: True
                 install path: /root/projects/py/landlords-server/.venv/lib/python3.8/site-packages/pydantic
               python version: 3.8.2 (default, Apr 27 2020, 15:53:34)  [GCC 9.3.0]
                     platform: Linux-4.19.84-microsoft-standard-x86_64-with-glibc2.29
     optional deps. installed: ['typing-extensions']

from pydantic import BaseModel

class UserInfo(BaseModel):
    """ for my application """
    name: str
    email: str

class GoogleUserInfo(UserInfo):
    """ google account """
    sub: str
    family_name: str
    given_name: str
    picture: str

class OtherOAuthUserInfo(UserInfo):
    ...

def sign_in(user_info: UserInfo):
    database.save(user_info)

def main():
    google_user_info = GoogleUserInfo(...) 
    other_user_info = OtherOAuthUserInfo(...)
    sign_in(UserInfo(google_user_info)) # error
    sign_in(UserInfo(other_user_info)) # error

I want to use up-casting. but, user_info variable is GoogleUserInfo instance in sign_in function.

Can I use up-casting?

[PrettyWood]

Hello @mcauto
I would go with something like this

from typing import Union

from pydantic import BaseModel

class BaseUserInfo(BaseModel):
    """ for my application """
    name: str
    email: str

class GoogleUserInfo(BaseUserInfo):
    """ google account """
    sub: str
    family_name: str
    given_name: str
    picture: str

class OtherOAuthUserInfo(BaseUserInfo):
    ...

and then either declare the main model and user parse_obj to avoid having to set __root__ manually:

class UserInfo(BaseModel):
    __root__: Union[GoogleUserInfo, OtherOAuthUserInfo]

UserInfo.parse_obj(google_user_infos)

or just

from pydantic.tools import parse_obj_as

UserInfo = Union[GoogleUserInfo, OtherOAuthUserInfo]

parse_obj_as(UserInfo, google_user_infos)

[mcauto]

Hello! @PrettyWood

Thank you for your time.

It's nice explanation.

Could you review my code?

UserInfo(**google_auth_info.dict())
UserInfo(**other_user_info.dict())

[PrettyWood]

@mcauto What should I review ? I don't get it sorry