Behaviour when deserializing tuples

...and probably also for sets, etc.

First of all, thank you for comments and changes after my last issue #61. I clearly understand the reasoning behind that.

Now I'm running into issues related to that. When trying to deserialize a dictionary that has a list but the dataclass requires tuples, I can't get the casting to work. I think the code speaks for itsself:

from dataclasses import dataclass
import typing

from dacite import from_dict, Config

TupleOfInts = typing.Tuple[int]

@dataclass
class Dataclass:
    values: TupleOfInts

from_dict(
    data_class=Dataclass,
    data={"values": [1,2,3]},
    config=Config(
        cast=[
            typing.Tuple, # I'd expect either of these to work
            tuple,
        ]
    )
)

dacite.exceptions.WrongTypeError: wrong type for field "values" - should be "typing.Tuple[int]" instead of "list"

I expected dacite to cast the list to a tuple and then confirm the actual values are ints. So I thought: Maybe I have to add the TupleOfInts to the cast parameter explicitly (which I'd prefer to avoid) but then I get another error:

  File "/usr/local/Cellar/python/3.7.5/Frameworks/Python.framework/Versions/3.7/lib/python3.7/typing.py", line 671, in __call__
    raise TypeError(f"Type {self._name} cannot be instantiated; "
TypeError: Type Tuple cannot be instantiated; use tuple() instead

btw: My editor complains when passing in a set as parameter for cast. Without having looked at the implementation, it seems the type hint List is more restrictive than necessary and Iterable will do the job, too.

konradhalas / dacite

Behaviour when deserializing tuples #73