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urllib.request.Request.data type erroring when using decode #11470
Description
When getting the data out of a urllib.request.Request object, mypy is erroring saying that decode is not supported even tho it is a bytes object (and does not error when at runtime).
$ cat t.py
from urllib.request import Request
req = Request("http://localhost:8080", data=b"req body")
if req.data:
print(dir(req.data))
print(type(req.data))
print(req.data.decode())
$ mypy t.py
t.py:8: error: Item "Buffer" of "Buffer | SupportsRead[bytes] | Iterable[bytes]" has no attribute "decode" [union-attr]
t.py:8: error: Item "SupportsRead[bytes]" of "Buffer | SupportsRead[bytes] | Iterable[bytes]" has no attribute "decode" [union-attr]
t.py:8: error: Item "Iterable[bytes]" of "Buffer | SupportsRead[bytes] | Iterable[bytes]" has no attribute "decode" [union-attr]
Found 3 errors in 1 file (checked 1 source file)
$ python t.py
[... 'decode', ...]
<class 'bytes'>
req body
$ python --version --version
Python 3.12.0 (main, Oct 2 2023, 20:56:14) [Clang 16.0.3 ]
$ mypy --version
mypy 1.8.0 (compiled: yes)I believe PR #10225 had made this an error as it changed bytes to Buffer.
- ReadOnlyBuffer: TypeAlias = bytes
- ReadableBuffer: TypeAlias = ReadOnlyBuffer | WriteableBuffer # stable
+ ReadOnlyBuffer: TypeAlias = Buffer # stable
+ ReadableBuffer: TypeAlias = Buffer # stableBefore: https://github.com/python/typeshed/blame/56aeeb677f27c6771e683314621521aff5c97cd1/stdlib/_typeshed/__init__.pyi#L230-L241
After: https://github.com/python/typeshed/blame/1e7e174b4fc4da6a66622168f8012c7ee0499392/stdlib/_typeshed/__init__.pyi#L263-L267
Deferred until #11422.
Activity
[-]urllib.request.Request.data type erroring when using decode[/-][+]`urllib.request.Request.data` type erroring when using `decode`[/+]aminalaee commentedon Feb 28, 2024
Isn't it because the
dataproperty can also beIterable[bytes]so.decode()is not available?I think that's not your case, but it's a possible case.
srittau commentedon Mar 15, 2024
The problem here is that the type of the
dataattribute depends on thedatapassed in, which might not have adecode()method. The solution is to makeRequestgeneric over the type of data, but we'll have to wait until #11422 is implemented. I've marked this issue as "deferred" for now.[urllib.request] Make `Request` generic over the type of `data`