from_dict does not fail when parsing a boolean for an integer field

[mcobzarenco]

from_dict does not fail when parsing a boolean for an integer field. I would expect the following code to fail. Instead it parses a dataclass where the field a is an bool instead of a int.

import serde

@serde.serde
class Foo:
    a: int

foo = serde.from_dict(Foo, {"a": True})
assert type(foo.a) == bool

PS awesome library btw, I've long wanted something like serde-rs in Python 🙌

EDIT: booleans in Python are implemented as a subclass of integers, so actually this may be expected behaviour

[yukinarit]

Hi @mcobzarenco
Thanks for being interested in pyserde!

pyserde relies on beartype for type checking and unfortunately this is the default behavior of beartype. But yeah, you're right, I believe this is not a bug in beartype because python's bool is a subclass of int.

>>> issubclass(bool, int)
True
>>> isinstance(True, int)
True
>>> isinstance(False, int)
True

If you want to be strict about int vs. bool, I would suggest to write a beartype custom validator as a workaround. Hope it helps.

import serde
from beartype.vale import Is
from typing import Annotated

StrictInt = Annotated[int, Is[lambda v: isinstance(v, int) and not isinstance(v, bool)]]

@serde.serde
class Foo:
    a: StrictInt

# raises serde.compat.SerdeError: Method __main__.Foo.__init__() parameter a=True violates type hint typing.Annotated[int, Is[lambda v: isinstance(v, int) and (not isinstance(v, bool))]], as bool True violates validator Is[lambda v: isinstance(v, int) and (not isinstance(v, bool))]:
foo = serde.from_dict(Foo, {"a": True})