What are some examples of using dataclass validators in Python?

Can you give me some examples of using dataclass validators in Python?

Sure! In Python, dataclass validators can be used to enforce constraints on the fields of a dataclass. For example, you can use the field function with a validator to ensure that a value meets certain criteria.

Can you show me a specific example?

Absolutely! Here's a simple example:

from dataclasses import dataclass, field
from typing import Any

def validate_age(value: int) -> int:
    if value < 0:
        raise ValueError('Age must be a non-negative integer')
    return value

@dataclass
class Person:
    name: str
    age: int = field(default=0, metadata={'validator': validate_age})

In this example, the validate_age function checks that the age is non-negative.

What happens if I try to create a Person with a negative age?

If you try to create a Person instance with a negative age, it will raise a ValueError. For example:

person = Person(name='Alice', age=-5)  # This will raise ValueError