I have simple Config class from FastAPI tutorial. But it seems like it uses old pydantic version. I run my code with pydantic v2 version and get a several errors. I fix almost all of them, but the last one I cannot fix yet. This is part of code which does not work:
from pydantic import AnyHttpUrl, HttpUrl, PostgresDsn, field_validatorfrom pydantic_settings import BaseSettingsfrom pydantic_core.core_schema import FieldValidationInfoload_dotenv()class Settings(BaseSettings): ... POSTGRES_SERVER: str = 'localhost:5432' POSTGRES_USER: str = os.getenv('POSTGRES_USER') POSTGRES_PASSWORD: str = os.getenv('POSTGRES_PASSWORD') POSTGRES_DB: str = os.getenv('POSTGRES_DB') SQLALCHEMY_DATABASE_URI: Optional[PostgresDsn] = None @field_validator("SQLALCHEMY_DATABASE_URI", mode='before') @classmethod def assemble_db_connection(cls, v: Optional[str], info: FieldValidationInfo) -> Any: if isinstance(v, str): return v postgres_dsn = PostgresDsn.build( scheme="postgresql", username=info.data.get("POSTGRES_USER"), password=info.data.get("POSTGRES_PASSWORD"), host=info.data.get("POSTGRES_SERVER"), path=f"{info.data.get('POSTGRES_DB') or ''}", ) return str(postgres_dsn)That is the error which I get:
sqlalchemy.exc.ArgumentError: Expected string or URL object, got MultiHostUrl('postgresql://user:password@localhost:5432/database')I check a lot of places, but cannot find how I can fix that, it looks like build method pass data to the sqlalchemy create_engine method as a MultiHostUrl instance instead of string. How should I properly migrate this code to use pydantic v2?
UPDATE
I have fixed that issue by changing typing for SQLALCHEMY_DATABASE_URI: Optional[PostgresDsn] = None to SQLALCHEMY_DATABASE_URI: Optional[str] = None.Because pydantic makes auto conversion of result for some reason. But I am not sure if that approach is the right one, maybe there are better way to do that?
