Validating detailed types in python dataclasses

Question

Python 3.7 was released a while ago, and I wanted to test some of the fancy new dataclass+typing features. Getting hints to work right is easy enough, with both

Answer 1

Just found this question.

pydantic can do full type validation for dataclasses out of the box. (admission: I built pydantic)

Just use pydantic's version of the decorator, the resulting dataclass is completely vanilla.

from datetime import datetime
from pydantic.dataclasses import dataclass

@dataclass
class User:
    id: int
    name: str = 'John Doe'
    signup_ts: datetime = None

print(User(id=42, signup_ts='2032-06-21T12:00'))
"""
User(id=42, name='John Doe', signup_ts=datetime.datetime(2032, 6, 21, 12, 0))
"""

User(id='not int', signup_ts='2032-06-21T12:00')

The last line will give:

    ...
pydantic.error_wrappers.ValidationError: 1 validation error
id
  value is not a valid integer (type=type_error.integer)