to_dict and from_dict do not support None as value for an Optional nested in Tuple

[Mindstan]

• mashumaro version: 3.0
• Python version: 3.6.9 (PyEnv, CPython)
• Operating System: Ubuntu 20.04

Description

I'm trying to set an optional value in a Tuple (in the example Tuple[Optional[int], int]) and export it in YAML, but it results in a TypeError. By looking at the generated code (see below), we can see the Optional is ignored by the builder.

What I Did

from dataclasses import dataclass, field
from typing import Tuple, Optional

from mashumaro.mixins.yaml import DataClassYAMLMixin

@dataclass
class Foo(DataClassYAMLMixin):
    bar: Tuple[Optional[int], int] = field(default_factory=lambda: (None, 42))

print(Foo().to_dict())

Output:

Traceback (most recent call last):
  File "test2.py", line 17, in <module>
    print(Foo().to_dict())
  File "<string>", line 7, in to_dict
TypeError: int() argument must be a string, a bytes-like object or a number, not 'NoneType'

Generated code for to_dict:

__main__.Foo:
def to_dict(self):
    kwargs = {}
    value = getattr(self, 'bar')
    if value is None:
        kwargs['bar'] = None
    else:
        kwargs['bar'] = [int(value[0]), int(value[1])]
        # should have been [int(value[0]) if value[0] is not None else None, int(value[1])]
    return kwargs
setattr(cls, 'to_dict', to_dict)

EDIT: from_dict also suffers from the same issue

[Fatal1ty]

It seems like could_be_none should be set to True for tuples and in other cases possibly. Thank you for spotting this, I will check different cases and try to fix it as soon as possible.

[peku-jamf]

@Fatal1ty May I ask, is this related problem? Can't get Optional working as I would expect. In my yaml file there is nothing like setup2, but I'd expect, since it is Optional, it will be silently ignored.

Traceback (most recent call last):
  File "<string>", line 12, in from_dict
  File "<string>", line 19, in from_dict
mashumaro.exceptions.MissingField: Field "setup2" of type Optional[str] is missing in MqSetup instance

code

@dataclass
class MqSetup(DataClassYAMLMixin):
    setup: int
    setup2: Optional[str]

[Fatal1ty]

@peku-jamf type Optional[str] means no more than that you can pass to setup2 values of type str or None. If you want to have a default value than you should write setup2: Optional[str] = None.

See docs: https://docs.python.org/3/library/typing.html#typing.Optional

[peku-jamf]

Thank you @Fatal1ty

[Fatal1ty]

@Mindstan Sorry for such a long delay, I was on vacation and tried to distract myself from the Internet. I have fixed this issue and released 3.0.1 version. You can give it a try!

[Mindstan]

Thanks, it works now in our project.