[Python] Cannot convert struct type from Pandas object column

[asfimport]

As reported on #4045. Interestingly, the datatype is inferred correctly.

>>> df = pd.DataFrame({'col': [{'ints': 5, 'strs': 'foo'}, {'ints': 6, 'strs': 'bar'}]})                                                                             
>>> df                                                                                                                                                               
                          col
0  {'ints': 5, 'strs': 'foo'}
1  {'ints': 6, 'strs': 'bar'}
>>> pa.Table.from_pandas(df)                                                                                                                                         
Traceback (most recent call last):
  File "<ipython-input-16-6eac5d0eec08>", line 1, in <module>
    pa.Table.from_pandas(df)
  File "pyarrow/table.pxi", line 1139, in pyarrow.lib.Table.from_pandas
    names, arrays, metadata = dataframe_to_arrays(
  File "/home/antoine/arrow/dev/python/pyarrow/pandas_compat.py", line 480, in dataframe_to_arrays
    types)
  File "/home/antoine/arrow/dev/python/pyarrow/pandas_compat.py", line 209, in construct_metadata
    field_name=sanitized_name)
  File "/home/antoine/arrow/dev/python/pyarrow/pandas_compat.py", line 151, in get_column_metadata
    logical_type = get_logical_type(arrow_type)
  File "/home/antoine/arrow/dev/python/pyarrow/pandas_compat.py", line 79, in get_logical_type
    raise NotImplementedError(str(arrow_type))
NotImplementedError: struct<ints: int64, strs: string>

Reporter: Antoine Pitrou / @pitrou

_{Note: This issue was originally created as ARROW-5161. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
Added to 0.15.0.

[asfimport]

Wes McKinney / @wesm:
This is working in master. I'll add a unit test

[asfimport]

Wes McKinney / @wesm:
This was fixed and tested in ARROW-5286