python-attrs / python-attrs/cattrs

cattrs structure string to List, instead of failing conversion

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#44 14 comments 0 reactions 0 assignees View on GitHub

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Dominant language
Python
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Merged PRs (30d)
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Description

@attr.s
class Model:
    field = attr.ib(type=List[str])

src_dict = {"field": "hello"}

cattrs.structure(src_dict, Model)

=> ["h", "e", "l", "l", "o"]

I'd expect it to fail converting.

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Research direction

Start by reproducing the provided cattrs.structure example with a List[str] field and a string value. Trace the structure conversion entry point to determine why the string is treated as an iterable, then add coverage showing the conversion should fail for this input. Done means the example raises a conversion error rather than producing a list of characters.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
backend
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
42/100

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