SQLAlchemy ORM models + Pydantic with custom composite Field

main.py

from uuid import UUID

from pydantic.class_validators import validator
from pydantic.main import BaseModel
from pydantic.types import UUID4
from sqlalchemy import Column, String, Uuid
from sqlalchemy.orm import declarative_base

Base = declarative_base()


class ContactModel(Base):
    __tablename__ = "contacts"

    id = Column(Uuid, primary_key=True)
    email = Column(String, nullable=False)


class Email(BaseModel):
    value: str

    class Config:
        orm_mode = True


class Id(BaseModel):
    value: UUID4

    class Config:
        orm_mode = True


def default_parser(value: str | dict) -> dict:
    if isinstance(value, str) and not value:
        raise ValueError("value cannot be empty")
    if isinstance(value, str) or isinstance(value, UUID):
        return {'value': value}
    return value


class Contact(BaseModel):
    id: Id
    email: Email

    class Config:
        orm_mode = True
        json_encoders = {
            Id: lambda v: str(v.value),
            Email: lambda v: v.value,
        }

    _parse_id = validator("id", pre=True, allow_reuse=True)(default_parser)
    _parse_email = validator("email", pre=True, allow_reuse=True)(default_parser)

    def dict(self, *args, **kwargs):
        base_dict = super().dict(*args, **kwargs)
        for field, value in base_dict.items():
            if isinstance(value, dict) and 'value' in value:
                base_dict[field] = value['value']
        return base_dict
  

test_schemas.py

import pytest

from uuid import UUID

from pydantic.error_wrappers import ValidationError

from main import Email, Contact, ContactModel, Id


def test_email_schema():
    email = Email(value='[email protected]')

    assert email.value == '[email protected]'


def test_contact_schema_id_as_dict():
    contact = Contact(
        **{
            'id': {'value': 'a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11'},
            'email': {'value': '[email protected]'}
        }
    )

    assert contact.id == Id(value=UUID('a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11'))
    assert contact.email.value == '[email protected]'


def test_contact_schema_id_as_str():
    contact = Contact(
        **{
            'id': 'a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11',
            'email': {'value': '[email protected]'}
        }
    )

    assert contact.id == Id(value=UUID('a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11'))
    assert contact.email.value == '[email protected]'


def test_contact_schema_email_as_dict():
    contact = Contact(
        **{
            'id': 'a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11',
            'email': {'value': '[email protected]'}
        }
    )

    assert contact.id == Id(value=UUID('a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11'))
    assert contact.email.value == '[email protected]'


def test_contact_schema_email_as_str():
    contact = Contact(
        **{
            'id': Id(value=UUID('a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11')),
            'email': '[email protected]'
        }
    )

    assert contact.id == Id(value=UUID('a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11'))
    assert contact.email.value == '[email protected]'


def test_contact_schema_dict_representation():
    contact = Contact(
        id=Id(value=UUID('a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11')),
        email='[email protected]'
    )

    assert contact.dict() == {
            'id': UUID('a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11'),
            'email': '[email protected]'
        }


def test_contact_schema_json_representation():
    contact = Contact(
        id=Id(value=UUID('a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11')),
        email='[email protected]'
    )

    assert contact.json(models_as_dict=False) == '{"id": "a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11", "email": "[email protected]"}'
    assert contact.json() == '{"id": {"value": "a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11"}, "email": {"value": "[email protected]"}}'


def test_contact_schema_raises_when_id_empty_string():

    with pytest.raises(ValidationError) as e:
        contact = Contact(
            id='',
            email='[email protected]'
        )

    assert 'value cannot be empty' in str(e.value)


def test_contact_schema_raises_when_email_empty_string():

        with pytest.raises(ValidationError) as e:
            contact = Contact(
                id=Id(value=UUID('a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11')),
                email=''
            )

        assert 'value cannot be empty' in str(e.value)


def test_contact_schema_from_model():
    model = ContactModel(
            id=UUID('a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11'),
            email='[email protected]'
        )

    contact = Contact.from_orm(model)

    assert contact.id == Id(value=UUID('a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11'))
    assert contact.email.value == '[email protected]'