Using pydantic to catch an invalid attribute setting

Question

The script below runs without error. I would like to catch the invalid attribute setting on the last line, where the value is not set to a positive integer.

from pydantic.dataclasses import dataclass
from pydantic import PositiveInt


@dataclass
class MyDataClass:
    value: PositiveInt


my_class = MyDataClass(value=10)
my_class.value = -1

Answer 1

If you're not opposed to using pydantic BaseModels you could just tell it to validate assignments as well.

from pydantic import BaseModel, PositiveInt

class MyDataClass(BaseModel):
    value: PositiveInt

    class Config:
        validate_assignment = True


my_class = MyDataClass(value=10)

# raises ValidationError
my_class.value = -1