dataclasses.asdict breaks when there aredefaultdicts in the dataclass attributes because it assumesdefaultdict anddict are the same thing, but in realitydefaultdict takes a default_factory as the first argument in its constructor.

Sincedataclasses.asdict alreadysupportsNamedTuples, I think its fair thatdefaultdict, which is also in the standard library, does not breakdataclasses.

Test:

fromdataclassesimportdataclass,asdictfromtypingimportDefaultDict,Listfromcollectionsimportdefaultdict@dataclassclassC:mp:DefaultDict[str,List]dd=defaultdict(list)dd["x"].append(12)c=C(mp=dd)d=asdict(c)# throws "TypeError: first argument must be callable or None"assertd== {"mp": {"x": [12]}}

https://bugs.python.org/issue35540

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March 22, 2022 18:23

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bpo-35540: Fix dataclasses.asdict support for defaultdict fields

7567680

dataclasses.asdict breaks when there are `defaultdict`s in the dataclassattributes because it assumes `defaultdict` and `dict` are the same thing,but in reality `defaultdict` takes a default_factory as the first argumentin its constructor. This change adds support for defaultdict fields.

kwsp force-pushed thefix-issue-35540 branch from82a5a4e to7567680Compare

March 22, 2022 19:15

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fix blurb

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MaxwellDupre commentedApr 25, 2022

Could you add a test please?

kwsp added2 commits

May 4, 2022 11:37

added tests for asdict() with defaultdict

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Merge branch 'fix-issue-35540' of github.com:kwsp/cpython into fix-is…

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…sue-35540

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kwsp commentedMay 4, 2022

Could you add a test please?

I just added a test for this

wrmsrmannequin mentioned this pull request

Apr 10, 2022

dataclasses.asdict breaks with defaultdict fields#79721

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Tests ok on Fedora.
Ref to bugs.python.org/issue35540 is not future proof, assume will be turned off at some time.

bedevere-bot added awaiting core review and removed awaiting review labels

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Jul 13, 2022

Merge branch 'main' into fix-issue-35540

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ericvsmith reviewed

Oct 4, 2022

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ericvsmith self-assigned this

Oct 4, 2022

check 'default_factory' attr on the type

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ericvsmith merged commitc46a423 intopython:main

Oct 7, 2022

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carljm added a commit to carljm/cpython that referenced this pull request

Oct 8, 2022

Merge branch 'main' into typewatch

29e38df

* main:  bpo-35540 dataclasses.asdict now supports defaultdict fields (pythongh-32056)pythonGH-91052: Add C API for watching dictionaries (pythonGH-31787)  bpo-38693: Use f-strings instead of str.format() within importlib (python#17058)

This was referencedOct 10, 2022

bpo-35540: Add collections.defaultdict support to dataclasses.{asdict,astuple}#11361

Closed

gh-98410: move getbufferproc and releasebufferproc to buffer.h#31158

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This was referencedOct 11, 2022

dataclasses.astuple breaks onDefaultDict#98169

Closed

gh-98169 dataclasses.astuple support DefaultDict#98170

Merged

mpage pushed a commit to mpage/cpython that referenced this pull request

Oct 11, 2022