parquetjs_lite_schema_write_read_with_async_cursor.ts

1import * as parquet from 'parquetjs-lite';
2
3async function example() {
4  // Declare a schema for the parquet file
5  const schema = new parquet.ParquetSchema({
6    name: { type: 'UTF8' },
7    quantity: { type: 'INT64' },
8    price: { type: 'DOUBLE' },
9    date: { type: 'TIMESTAMP_MILLIS' },
10    in_stock: { type: 'BOOLEAN' }
11  });
12
13  // Create a new ParquetWriter to write the file 'fruits.parquet'
14  const writer = await parquet.ParquetWriter.openFile(schema, 'fruits.parquet');
15
16  // Append data rows
17  await writer.appendRow({ name: 'apples', quantity: 10n, price: 2.5, date: new Date(), in_stock: true });
18  await writer.appendRow({ name: 'oranges', quantity: 20n, price: 3.5, date: new Date(), in_stock: true });
19  
20  // Close the writer
21  await writer.close();
22
23  // Create a new reader and read all rows
24  const reader = await parquet.ParquetReader.openFile('fruits.parquet');
25  const cursor = reader.getCursor();
26
27  let record = null;
28  while (record = await cursor.next()) {
29    console.log(record);
30  }
31
32  await reader.close();
33}
34
35example().catch(console.error);