stream-csv-as-json

stream-csv-as-json

stream-csv-as-json is a micro-library of node.js stream components with minimal dependencies for creating custom data processors oriented on processing huge CSV files while requiring a minimal memory footprint. It can parse CSV files far exceeding available memory. Even individual primitive data items can be streamed piece-wise. Streaming SAX-inspired event-based API is included as well.

stream-csv-as-json is a companion project for stream-json and it is meant to be used with its filters, streamers and general infrastructure.

Available components:

• Streaming JSON Parser.
  • It produces a SAX-like token stream.
  • Optionally it can pack individual values.
  • The main module provides helpers to create a parser.
• Essentials:
  • AsObjects uses the first row as a list of field names and produces rows as shallow objects with named fields.
  • Stringer converts a token stream back into a JSON text stream.

All components are meant to be building blocks to create flexible custom data processing pipelines. They can be extended and/or combined with custom code. They can be used together with stream-chain and stream-json to simplify data processing.

This toolkit is distributed under New BSD license.

Introduction

const {chain}  = require('stream-chain');

const {parser} = require('stream-csv-as-json');
const {asObjects} = require('stream-csv-as-json/AsObjects');
const {StreamValues} = require('stream-json/streamers/StreamValues');

const fs   = require('fs');
const zlib = require('zlib');

const pipeline = chain([
  fs.createReadStream('sample.csv.gz'),
  zlib.createGunzip(),
  parser(),
  asObjects(),
  streamValues(),
  data => {
    const value = data.value;
    return value && value.department === 'accounting' ? data : null;
  }
]);

let counter = 0;
pipeline.on('data', () => ++counter);
pipeline.on('end', () =>
  console.log(`The accounting department has ${counter} employees.`));

See the full documentation in Wiki.

Installation

npm install --save stream-csv-as-json
# or:
yarn add stream-csv-as-json

Use

The whole library is organized as a set of small components, which can be combined to produce the most effective pipeline. All components are based on node.js streams, and events. They implement all required standard APIs. It is easy to add your own components to solve your unique tasks.

The code of all components is compact and simple. Please take a look at their source code to see how things are implemented, so you can produce your own components in no time.

Obviously, if a bug is found, or a way to simplify existing components, or new generic components are created, which can be reused in a variety of projects, don't hesitate to open a ticket, and/or create a pull request.

Release History

• 1.0.1 minor readme tweaks, added TypeScript typings and the badge.
• 1.0.0 the first 1.0 release.