[Python] __arrow_array__ does not work for ExtensionTypes in Table.from_pandas #23334
Description
When someone has a custom ExtensionType defined in Python, and an array class that gets converted to that (through \_\_arrow_array\_\_), the conversion in pyarrow works with the array class, but not yet for the array stored in a pandas DataFrame.
Eg using my definition of ArrowPeriodType in pandas-dev/pandas#28371, I see:
In [15]: pd_array = pd.period_range("2012-01-01", periods=3, freq="D").array
In [16]: pd_array
Out[16]:
<PeriodArray>
['2012-01-01', '2012-01-02', '2012-01-03']
Length: 3, dtype: period[D]
In [17]: pa.array(pd_array)
Out[17]:
<pyarrow.lib.ExtensionArray object at 0x7f657cf78768>
[
15340,
15341,
15342
]
In [18]: df = pd.DataFrame({'periods': pd_array})
In [19]: pa.table(df)
...
ArrowInvalid: ('Could not convert 2012-01-01 with type Period: did not recognize Python value type when inferring an Arrow data type', 'Conversion failed for column periods with type period[D]')(this is working correctly for array objects whose \_\_arrow_array\_\_ is returning a built-in pyarrow Array).
Reporter: Joris Van den Bossche / @jorisvandenbossche
Assignee: Joris Van den Bossche / @jorisvandenbossche
PRs and other links:
Note: This issue was originally created as ARROW-7022. Please see the migration documentation for further details.