[SPARK-46540][PYTHON] Respect column names when Python data source read function outputs named Row objects #44531
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HyukjinKwon
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| pylist[col].append(column_converters[col](result[col])) | ||
| # Assign output values by name of the field, not position, if the result is a | ||
| # named `Row` object. | ||
| if isinstance(result, Row) and hasattr(result, "__fields__"): |
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Can we match the implementation with python worker? See assign_cols_by_name at worker.py.
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This is actually different from assign_cols_by_name which re-arranges arrow batch columns by the arrow type names. Here we want to match a single named Row object to the return schema. The only way to tell whether it's named Row(a=1, b=1) from an unnamed Row(1,2) is by checking this __fields__.
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Merged to master. |
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What changes were proposed in this pull request?
This PR fixes an issue when the
readmethod of Python DataSourceReader yields namedRowobjects.Currently, it ignores the name in the Row object:
The result should be
[Row(a=1, b=2), Row(a=2, b=3)], instead of[Row(a=1 , b=2), Row(a=3, b=2)].Why are the changes needed?
To fix an incorrect behavior.
Does this PR introduce any user-facing change?
No
How was this patch tested?
Unit test
Was this patch authored or co-authored using generative AI tooling?
No