JSONPath Typescript

Type inference for JSONPath queries, as per the JSONPath query expressions RFC (see limitations below).

npm i jsonpath-ts

Usage

1import { Parse } from "jsonpath-ts";
2
3type Result = Parse<"$.store.book[*].author[2:6]", Data>;
4//	 ^? ["Herman Melville", "J. R. R. Tolkien"]
5
6// Given input type
7export type Data = {
8  store: {
9    book: [
10      {
11        category: "reference";
12        author: "Nigel Rees";
13        title: "Sayings of the Century";
14        price: 8.95;
15      },
16      {
17        category: "fiction";
18        author: "Evelyn Waugh";
19        title: "Sword of Honour";
20        price: 12.99;
21      },
22      {
23        category: "fiction";
24        author: "Herman Melville";
25        title: "Moby Dick";
26        isbn: "0-553-21311-3";
27        price: 8.99;
28      },
29      {
30        category: "fiction";
31        author: "J. R. R. Tolkien";
32        title: "The Lord of the Rings";
33        isbn: "0-395-19395-8";
34        price: 22.99;
35      }
36    ];
37    bicycle: {
38      color: "red";
39      price: 399;
40    };
41  };
42};

Limitations

• Slice steps not supported (::-1)
• Filtering not supported (?@.hasField)
• Descendant segments not supported ($...X)

How does it work?

This implementation first converts the input path into an abstract, shallow ordered tree of Selectors, such as NameSelector, IndexSelector etc. This representation is then iterated over to retrieve the derive the correct type from the data.

This functionality can be imported independently via:

1import {
2	ParsePath, // Input path -> ParsedPath
3	ExtractValue // ParsedPath -> Return data type
4} from "jsonpath-ts