JSONPath defines a string syntax for selecting and extracting JSON (RFC 8259) values from within a given JSON value.

This library is a Dart implementation of the RFC 9535 JsonPath specification. It is also expected to pass the latest version of the Compliance Test Suite. If you find a missing or incorrectly implemented feature, please open an issue.

For installation instructions and a detailed API documentation, see the pub.dev page.

import 'dart:convert';

import 'package:json_path/json_path.dart';

void main() {
  final json = jsonDecode('''
{
  "store": {
    "book": [
      {
        "category": "reference",
        "author": "Nigel Rees",
        "title": "Sayings of the Century",
        "price": 8.95
      },
      {
        "category": "fiction",
        "author": "Evelyn Waugh",
        "title": "Sword of Honour",
        "price": 12.99
      },
      {
        "category": "fiction",
        "author": "Herman Melville",
        "title": "Moby Dick",
        "isbn": "0-553-21311-3",
        "price": 8.99
      },
      {
        "category": "fiction",
        "author": "J. R. R. Tolkien",
        "title": "The Lord of the Rings",
        "isbn": "0-395-19395-8",
        "price": 22.99
      }
    ],
    "bicycle": {
      "color": "red",
      "price": 19.95
    }
  }
}  
  ''');

  final prices = JsonPath(r'$..price');

  print('All prices in the store:');

  /// The following code will print:
  ///
  /// $['store']['book'][0]['price']:	8.95
  /// $['store']['book'][1]['price']:	12.99
  /// $['store']['book'][2]['price']:	8.99
  /// $['store']['book'][3]['price']:	22.99
  /// $['store']['bicycle']['price']:	19.95
  prices
      .read(json)
      .map((match) => '${match.path}:\t${match.value}')
      .forEach(print);
}

Each JsonPathMatch produced by the .read() method contains the .pointer property which is a valid JSON Pointer and can be used to alter the referenced value. If you only need to manipulate JSON data, check out my JSON Pointer implementation.

The JSONPath parser may be extended with user-defined functions. The user-defined functions take precedence over the built-in ones specified by the standard. Currently, only functions of 1 and 2 arguments are supported.

To create your own function:

1. Import package:json_path/fun_sdk.dart.
2. Create a class implementing either Fun1 (1 argument) or Fun2 (2 arguments).

To use it:

1. Create a new JsonPathParser with your function: final parser = JsonPathParser(functions: [MyFunction()]);
2. Use it to parse you expression: final jsonPath = parser.parse(r'$[?my_function(@)]');

For more details see the included example.

This package comes with some non-standard functions which you might find useful.

• count(<NodeList>) - returns the number of nodes selected by the argument
• index(<SingularNodeList>) - returns the index under which the array element is referenced by the parent array
• key(<SingularNodeList>) - returns the key under which the object element is referenced by the parent object
• is_array(<Maybe>) - returns true if the value is an array
• is_boolean(<Maybe>) - returns true if the value is a boolean
• is_number(<Maybe>) - returns true if the value is a number
• is_object(<Maybe>) - returns true if the value is an object
• is_string(<Maybe>) - returns true if the value is a string
• reverse(<Maybe>) - reverses the string
• siblings(<NodeList>) - returns the siblings for the nodes
• xor(<bool>, <bool>) - returns the XOR of two booleans arguments

To use them, import package:json_path/fun_extra.dart and supply them to the JsonPath() constructor:

final jsonPath = JsonPathParser(functions: [
  const Key(),
  const Reverse(),
]).parse(r'$[?key(@) == reverse(key(@))]');

• Standard development
• Feature comparison matrix