[Python] StructArray.sort() errors with default arguments

[a-reich]

Describe the bug, including details regarding any error messages, version, and platform.

StructArray's sort method is documented to have the parameter by: str or None, default None, however a simple example that leaves the argument as None raises:

arr = pa.array([{'x': 1, 'y': True}, {'x': 3.4, 'y': False}])
arr.sort()
####### exception
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "pyarrow/array.pxi", line 3971, in pyarrow.lib.StructArray.sort
  File "/home/asaf/.local/lib/python3.12/site-packages/pyarrow/compute.py", line 263, in wrapper
    return func.call(args, options, memory_pool)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "pyarrow/_compute.pyx", line 385, in pyarrow._compute.Function.call
  File "pyarrow/error.pxi", line 154, in pyarrow.lib.pyarrow_internal_check_status
  File "pyarrow/error.pxi", line 91, in pyarrow.lib.check_status
pyarrow.lib.ArrowInvalid: Invalid sort key column: No match for FieldRef.Name() in x: double
y: bool

I am running pyarrow 16.0.0, Python 3.12, on Windows WSL.

I think the cause is a simple mistake in this line?

arrow/python/pyarrow/array.pxi

Line 3973 in b609de3

options=_pc().SortOptions(sort_keys=[("", order)], **kwargs)

I can send a basic PR with that fix and a test soon. But I'm not sure if I'll be able to build & test locally. Thanks!

Component(s)

Python

[jorisvandenbossche]

@a-reich Thanks for the report, a PR is certainly welcome!

[raulcd]

As per how to build and test, If you add a test that reproduces the issue it can be tested on CI.

[a-reich]

take

[jorisvandenbossche]

Issue resolved by pull request 41495
#41495