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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"asdict() on dataclass with defaultdict raises TypeError: \"first argument must be callable or None \"","articleBody":"\u003c!--\r\n  If you're new to Python and you're not sure whether what you're experiencing is a bug, the CPython issue tracker is not\r\n  the right place to seek help. Consider the following options instead:\r\n\r\n  - reading the Python tutorial: https://docs.python.org/3/tutorial/\r\n  - posting in the \"Users\" category on discuss.python.org: https://discuss.python.org/c/users/7\r\n  - emailing the Python-list mailing list: https://mail.python.org/mailman/listinfo/python-list\r\n  - searching our issue tracker (https://github.com/python/cpython/issues) to see if\r\n    your problem has already been reported\r\n--\u003e\r\n\r\n# Bug report\r\n\r\nMinimal working example:\r\n\r\n```python \r\nfrom dataclasses import dataclass, field, asdict\r\nfrom typing import DefaultDict\r\nfrom collections import defaultdict\r\n\r\ndef default_list_dict():\r\n    return defaultdict(list)\r\n\r\n@dataclass\r\nclass Data:\r\n    metadata: DefaultDict = field(default_factory=default_list_dict)\r\n    \r\nD = Data() # =\u003e Data(metadata=defaultdict(\u003cclass 'list'\u003e, {}))\r\nasdict(D)\r\n```\r\n\r\n* Expected output: `{'metadata': defaultdict(list, {})}`\r\n* Got instead: `TypeError: first argument must be callable or None`\r\n\r\n\u003cdetails\u003e\r\n\u003csummary\u003eDisplay traceback\u003c/summary\u003e\r\n\r\n```python-traceback\r\n---------------------------------------------------------------------------\r\nTypeError                                 Traceback (most recent call last)\r\nCell In[1], line 13\r\n     10     metadata: DefaultDict = field(default_factory=default_list_dict)\r\n     12 D = Data()\r\n---\u003e 13 asdict(D)\r\n\r\nFile ~/miniconda3/lib/python3.10/dataclasses.py:1238, in asdict(obj, dict_factory)\r\n   1236 if not _is_dataclass_instance(obj):\r\n   1237     raise TypeError(\"asdict() should be called on dataclass instances\")\r\n-\u003e 1238 return _asdict_inner(obj, dict_factory)\r\n\r\nFile ~/miniconda3/lib/python3.10/dataclasses.py:1245, in _asdict_inner(obj, dict_factory)\r\n   1243 result = []\r\n   1244 for f in fields(obj):\r\n-\u003e 1245     value = _asdict_inner(getattr(obj, f.name), dict_factory)\r\n   1246     result.append((f.name, value))\r\n   1247 return dict_factory(result)\r\n\r\nFile ~/miniconda3/lib/python3.10/dataclasses.py:1275, in _asdict_inner(obj, dict_factory)\r\n   1273     return type(obj)(_asdict_inner(v, dict_factory) for v in obj)\r\n   1274 elif isinstance(obj, dict):\r\n-\u003e 1275     return type(obj)((_asdict_inner(k, dict_factory),\r\n   1276                       _asdict_inner(v, dict_factory))\r\n   1277                      for k, v in obj.items())\r\n   1278 else:\r\n   1279     return copy.deepcopy(obj)\r\n\r\nTypeError: first argument must be callable or None\r\n```\r\n\r\n\u003c/details\u003e\r\n\r\n# Your environment\r\n\r\n\u003c!-- Include as many relevant details as possible about the environment you experienced the bug in --\u003e\r\n\r\n- CPython versions tested on: Python 3.10.11 [GCC 11.2.0] on linux\r\n- Operating system and architecture: Linux 6.1.31-2-MANJARO #1 SMP PREEMPT_DYNAMIC Sun Jun  4 12:31:46 UTC 2023 x86_64 GNU/Linux\r\n\r\n\u003c!--\r\nYou can freely edit this text. Remove any lines you believe are unnecessary.\r\n--\u003e\r\n","author":{"url":"https://github.com/johentsch","@type":"Person","name":"johentsch"},"datePublished":"2023-06-26T16:06:52.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":3},"url":"https://github.com/106113/cpython/issues/106113"}