[ARROW-5532] [JS] Field Metadata Not Read

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.13.0
• Fix Version/s: 0.14.0
• Component/s: JavaScript
• Labels: Javas
• Environment: Mac OSX 10.14, Chrome 74
• External issue URL: https://github.com/apache/arrow/issues/4495
• Assignee: Paul Taylor
• Reporter: Trey Hakanson
• Created: 07/Jun/19 22:40
• Updated: 11/Jan/23 07:41
• Resolved: 21/Jun/19 22:14

Description

Field metadata is not read when using @apache-arrow/ts@0.13.0. Example below also uses pyarrow==0.13.0

Steps to reproduce:

Adding metadata:

toarrow.py

import pyarrow as pa
import pandas as pd

source = "sample.csv"
output = "sample.arrow"
df = pd.read_csv(source)
table = pa.Table.from_pandas(df)
schema = pa.schema([
 column.field.add_metadata({"foo": "bar"}))
 for column
 in table.columns
])
writer = pa.RecordBatchFileWriter(output, schema)
writer.write(table)
writer.close()

Reading field metadata using pyarrow:

readarrow.py

source = "sample.arrow"
field = "foo"
reader = pa.RecordBatchFileReader(source)
reader.schema.field_by_name(field).metadata # Correctly shows `{"foo": "bar"}`

Reading field metadata using @apache-arrow/ts:

toarrow.ts

import { Table, Field, Type } from "@apache-arrow/ts";

const url = "https://example.com/sample.arrow";
const buf = await fetch(url).then(res => res.arrayBuffer());
const table = Table.from([new Uint8Array(buf)]);
for (let field of table.schema.fields) {
 field.metadata; // Incorrectly shows an empty map
}