phpsxg opened a new issue, #14728:
URL: https://github.com/apache/arrow/issues/14728
### Describe the usage question you have. Please include as many useful
details as possible.
pa.field sets the metadata parameter, prints schema.metadata, but the
metadata of columns is empty, how to correctly display the metadata of columns
```
class Dimension:
INSTRUMENT_TYPE = 'instrument_type'
INSTRUMENT_CODE = 'instrument_code'
INSTRUMENT_NAME = 'instrument_name'
schema = pa.schema([
pa.field(Dimension.INSTRUMENT_CODE, pa.string(),
metadata={b"table_filed": b"FUND_CODE"}),
pa.field(Dimension.INSTRUMENT_NAME, pa.string(),
metadata={b"table_filed": b"FUND_NAME"}),
pa.field(Dimension.INSTRUMENT_TYPE, pa.string())
],
metadata={
Dimension.INSTRUMENT_CODE: 'code',
Dimension.INSTRUMENT_NAME: 'name',
Dimension.INSTRUMENT_TYPE: 'type',
}
)
df = cls.query(sql)
df.rename(columns=cls.etl_rename_dict, inplace=True)
df[Dimension.INSTRUMENT_TYPE] = InstrumentType.FUND
table = pa.Table.from_pandas(df, schema=cls.schema)
# pq.write_table(table, 'test_parquet')
table_schema = table.schema
print(table_schema.metadata)
```
**Print the results**
```
{b'instrument_code': b'code', b'instrument_name': b'name',
b'instrument_type': b'type', b'pandas': b'{"index_columns": [],
"column_indexes": [{"name": null, "field_name": null, "pandas_type": "unicode",
"numpy_type": "object", "metadata": {"encoding": "UTF-8"}}], "columns":
[{"name": "instrument_code", "field_name": "instrument_code", "pandas_type":
"unicode", "numpy_type": "object", "metadata": null}, {"name":
"instrument_name", "field_name": "instrument_name", "pandas_type": "unicode",
"numpy_type": "object", "metadata": null}, {"name": "instrument_type",
"field_name": "instrument_type", "pandas_type": "unicode", "numpy_type":
"object", "metadata": null}], "creator": {"library": "pyarrow", "version":
"10.0.0"}, "pandas_version": "1.5.1"}'}
```
- python:3.10
- pyarrow: 10.0.0
### Component(s)
Parquet, Python
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