json_path 0.5.0-dev.3

Implementation of JSONPath expressions like "$.store.book[2].price". Reads and writes values in parsed JSON objects.

JSONPath in Dart

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
  /// $['store']['bicycle']['price']:	19.95
  prices
      .read(json)
      .map((node) => '${node.path}:\t${node.value}')
      .forEach(print);
}

Features and Limitations

This library follows the JsonPath internet draft specification. Since the spec itself is an evolving document, this implementation may lag behind, and some features may not be implemented in-full. Please refer to the tests (there are hundreds of them, including the CTS) to see what is supported.

Currently supported built-in functions:

• length()
• count()
• match()
• search()

Data manipulation

Each Node 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.

User-defined functions (beta)

The JSONPath parser may be extended by user-defined functions. The user-defined functions take precedence over the built-in ones which are defined by the standard. The functions are polymorphic: you may define functions with the same name, and the parser will pick the first of them which fits the use case (the return type, the number and the type or arguments).

References

• Standard development
• Feature comparison matrix