@json/path-transform

Transforms JSON objects using a path-based approach.

Description

This package provides a simple way to transform JSON objects using a path-based approach.

The purpose is to make it possible to write declarative transformations for json objects, hence make it useable in a configuration file or from user inputs.

Installation

Using npm

npm install @json/path-transform

Using yarn

yarn add @json/path-transform

Using pnpm

pnpm add @json/path-transform

Usage

The schema defines the transformation rules. The keys are the target keys and the values are the paths to the source keys.

import { PathTransform } from '@json/path-transform';

const schema = {
  name: '$.user.name',
  age: '$.user.age',
};

const data = {
  user: {
    name: 'John Doe',
    age: 30,
  },
};

const transformer = new PathTransform(schema).compile();

console.log(transformer(data)); // { name: 'John Doe', age: 30 }

Syntax

The JSONPath syntax is used to define the paths. The package uses the jsonpath-plus package under the hood to resolve the paths.

Exmaples can be found at https://goessner.net/articles/JsonPath/.

Root ($) key

The root key can be used to define the root of the object at any given depth. This copies the main object to that level.

import { PathTransform } from '@json/path-transform';

const schema = {
  $: '$.user',
};

const data = {
  user: {
    name: 'John Doe',
    age: 30,
  },
};

const transformer = new PathTransform(schema).compile();

console.log(transformer(data)); // { name: 'John Doe', age: 30 }

Performance

The performance is dependant on the complexity of the schema and the size of the data. The package makes a AOT compilation of the schema to make the transformation as fast as possible, and uses jsonpath-plus package under to hood to resolve results from each path.

On a M1 Macbook Air (16GB RAM) we can expect the following performance as seen under the benchmark folder.

| Test Name | ops/sec | Confidence Interval | |-----------------|--------------|---------------------| | root | 4,907,733 | ±0.20% | | allAuthors | 479,267 | ±0.35% | | allAuthorsDot | 1,007,505 | ±1.30% | | addKey | 449,904 | ±0.76% |