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TypeError on from_dict on dataclass with nested dict and tuple

See original GitHub issue

When creating a dataclass with a nested dict and a tuple, from_dict() does not work.

For a minimal working example:

from typing import Dict, Tuple
from dataclasses import dataclass
from dataclasses_json import DataClassJsonMixin

@dataclass
class TestClass(DataClassJsonMixin):
    nested_dict: Dict[str, Dict[Tuple[str], int]]

my_test = TestClass.from_dict({"nested_dict": {"a":{("b", "c"): 1, "c": 2}, "d": {}}})

This yields:

Traceback (most recent call last):
  File "[PROJECT_PATH]python3.8/site-packages/dataclasses_json/core.py", line 263, in _decode_generic
    res = _get_type_cons(type_)(xs)
  File "/usr/local/opt/python@3.8/Frameworks/Python.framework/Versions/3.8/lib/python3.8/typing.py", line 727, in __call__
    raise TypeError(f"Type {self._name} cannot be instantiated; "
TypeError: Type Tuple cannot be instantiated; use tuple() instead
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "[PROJECT_PATH]python3.8/site-packages/dataclasses_json/core.py", line 263, in _decode_generic
    res = _get_type_cons(type_)(xs)
  File "[PROJECT_PATH]python3.8/site-packages/dataclasses_json/core.py", line 309, in <genexpr>
    items = (_decode_generic(type_arg, x, infer_missing) for x in xs)
  File "[PROJECT_PATH]python3.8/site-packages/dataclasses_json/core.py", line 265, in _decode_generic
    res = type_(xs)
  File "/usr/local/opt/python@3.8/Frameworks/Python.framework/Versions/3.8/lib/python3.8/typing.py", line 727, in __call__
    raise TypeError(f"Type {self._name} cannot be instantiated; "
TypeError: Type Dict cannot be instantiated; use dict() instead
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "[PROJECT_PATH]python3.8/site-packages/IPython/core/interactiveshell.py", line 3437, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-15-a734de727315>", line 1, in <module>
    bob = TestClass.from_dict({"nested_dict": {"a":{("b", "c"): 1, "c": 2}, "d": {}}})
  File "[PROJECT_PATH]python3.8/site-packages/dataclasses_json/api.py", line 83, in from_dict
    return _decode_dataclass(cls, kvs, infer_missing)
  File "[PROJECT_PATH]python3.8/site-packages/dataclasses_json/core.py", line 201, in _decode_dataclass
    init_kwargs[field.name] = _decode_generic(field_type,
  File "[PROJECT_PATH]python3.8/site-packages/dataclasses_json/core.py", line 265, in _decode_generic
    res = type_(xs)
  File "/usr/local/opt/python@3.8/Frameworks/Python.framework/Versions/3.8/lib/python3.8/typing.py", line 727, in __call__
    raise TypeError(f"Type {self._name} cannot be instantiated; "
TypeError: Type Dict cannot be instantiated; use dict() instead

Is there anything I am obviously doing wrong or a workaround without getting rid of the type annotations?

Issue Analytics

State:
Created 2 years ago
Comments:5 (3 by maintainers)

Top GitHub Comments

1reaction

christian-steinmeyercommented, Jun 5, 2021

Yes, thanks!

0reactions

pearceeverydaylabscommented, Jun 5, 2021

@christian-steinmeyer can this be closed now that #297 is merged?

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