[Python] How do I do type checking before casting using pydantic?

I created a class using the dataclass decorator of pydantic and I want to check the type of an argument before it becomes an attribute of the class. This is my code:

from pydantic.dataclasses import dataclass
from pydantic import validator

@dataclass
class Person(object):
name: Optional[str] = None

@validator('name')
def name_must_be_str(cls, v):
if type(v) is not str:
raise TypeError("'name' must be str, not " + type(v).__name__)
return v


Now when I create an instance like person = Person(12), the argument becomes a string, too ('12'). How can I check the type before the instance casts the argument to a string?

Continue reading...