BUG: pandas.read_parquet no longer accepting a file-like object

[DavidFarago]

Code Sample, a copy-pastable example

from io import BytesIO
import numpy as np
import pandas as pd
import pytest

def test_read_parquet_on_stream():
    stream = BytesIO()
    df = pd.DataFrame({'col1': [1, 2], 'col2': [3, 4]})
    df.to_parquet(stream)
    result = pd.read_parquet(stream)
    assert np.array_equal(result.values, df.values)

Problem description

The documentation of pandas.read_parquet() (see 1) says

Parameters: path: str, path object or file-like object

It is quite handy to be able to use a stream as parameter. It used to work with pandas version 1.0.3, but causes the error below for pandas version 1.0.4.

Expected Output

I expect the test to pass silently, which it does when using pandas == 1.0.3.

Output

But for pandas == 1.0.4, the test case fails due to stream not being a path-like object:

tests/util/test_parquet_util.py:388 (test_read_parquet_on_stream)
def test_read_parquet_on_stream():
stream = BytesIO()
df = pd.DataFrame({'col1': [1, 2], 'col2': [3, 4]})
df.to_parquet(stream)

  result = pd.read_parquet(stream)

tests/util/test_parquet_util.py:393:

---

/usr/local/lib/python3.7/dist-packages/pandas/io/parquet.py:315: in read_parquet
return impl.read(path, columns=columns, **kwargs)
/usr/local/lib/python3.7/dist-packages/pandas/io/parquet.py:131: in read
path, filesystem=get_fs_for_path(path), **kwargs
/usr/local/lib/python3.7/dist-packages/pyarrow/parquet.py:1019: in init
self.paths = _parse_uri(path_or_paths)
/usr/local/lib/python3.7/dist-packages/pyarrow/parquet.py:49: in _parse_uri
path = _stringify_path(path)

---

path = <_io.BytesIO object at 0x7f07d0e77530>

def _stringify_path(path):
    """
    Convert *path* to a string or unicode path if possible.
    """
    if isinstance(path, six.string_types):
        return path

    # checking whether path implements the filesystem protocol
    try:
        return path.__fspath__()  # new in python 3.6
    except AttributeError:
        # fallback pathlib ckeck for earlier python versions than 3.6
        if _has_pathlib and isinstance(path, pathlib.Path):
            return str(path)

  raise TypeError("not a path-like object")

E TypeError: not a path-like object

/usr/local/lib/python3.7/dist-packages/pyarrow/util.py:84: TypeError

Details

Besides pandas, my requirements.txt contains the following relevant dependencies:

pyarrow ~= 0.15.1
pytest ~= 5.3.5
pyyaml ~= 5.1.2

My Python versions are 3.6.10 and 3.7.7.

[TomAugspurger]

Duplicate of #34467. Should have 1.0.5 out with a fix later today or tomorrow.