@trkm/object-json-path-ts

Using a small subset of JSONpath features, object-json-path-ts gets or sets a value in a JSON object.

Features

• A 100% typescript library.

Usage

Construct and access an object using JSONPath. The two functions provided are:

• insertIntoObject - Inserts a value to an object given a JSON path.
• getFromObject - Returns the value from a JSON path.

insertIntoObject

Inserts a value to an object given a JSON path.

1import { insertIntoObject } from '@trkm/object-json-path-ts';
2
3// build an admin using one path/value at a time.
4const adminUser = {};
5insertIntoObject(adminUser, { path: 'fullName', value: 'Happy Admin' });
6insertIntoObject(adminUser, { path: 'privileges', value: ['admin', 'reader'] });
7
8// Resulting adminUser value
9{
10  fullName: 'Happy Admin',
11  privileges: [ 'admin', 'reader' ]
12}
13
14// build a user providing multiple path/values at the same time.
15const user = {};
16insertIntoObject(user, [
17  { path: 'name.first', 'Happy'},
18  { path: 'name.last', 'User'}
19]);
20
21// Resulting user value
22{
23  name: {
24    first: 'Happy',
25    last: 'User'
26  }
27}

getFromObject

Returns a value from an object given a JSON path.

1import { getFromObject } from 'object-json-path-ts';
2
3
4const user = {
5  name: {
6    first: 'Happy',
7    last: 'User'
8  }
9};
10
11const value = getFromObject(user, 'name.first');
12

Intent

The intent is to compose objects whose shapes are not known ahead of time. The following code uses javascript object composition:

1const firstName = 'Happy';
2const lastName = 'User';
3
4const user = {
5  name: {
6    first: firstName,
7    last: lastName,
8  }
9}

However, this requires knowledge of the object's shape at development time.

Example Usage

We want to build an object based on web page context dynamically. We pull context from different sources on the page, such as HTML parameters, cookies, local storage, etc., and store them in an object. Instead of composing the final object using javascript, we define the mapping between a given context value and the object using JSON. The JSON is passed to a builder, http-context for example, which uses this library to get and set values to a javascript object.

Development

See the monorepo readme.

License

Licensed under MIT.