json_path 0.7.3 json_path: ^0.7.3 copied to clipboard
Implementation of RFC 9535 - JSONPath: Query Expressions for JSON. Reads and writes values in parsed JSON objects using queries like `$.store.book[2].price`.
RFC 9535 - JSONPath: Query Expressions for JSON in Dart #
JSONPath defines a string syntax for selecting and extracting JSON (RFC 8259) values from within a given JSON value.
This library is a Dart implementation of the RFC 9535 JsonPath specification. It is also expected to pass the latest version of the Compliance Test Suite. If you find a missing or incorrectly implemented feature, please open an issue.
For installation instructions and a detailed API documentation, see the pub.dev page.
Usage example: #
import 'dart:convert';
import 'package:json_path/json_path.dart';
void main() {
final json = jsonDecode('''
{
"store": {
"book": [
{
"category": "reference",
"author": "Nigel Rees",
"title": "Sayings of the Century",
"price": 8.95
},
{
"category": "fiction",
"author": "Evelyn Waugh",
"title": "Sword of Honour",
"price": 12.99
},
{
"category": "fiction",
"author": "Herman Melville",
"title": "Moby Dick",
"isbn": "0-553-21311-3",
"price": 8.99
},
{
"category": "fiction",
"author": "J. R. R. Tolkien",
"title": "The Lord of the Rings",
"isbn": "0-395-19395-8",
"price": 22.99
}
],
"bicycle": {
"color": "red",
"price": 19.95
}
}
}
''');
final prices = JsonPath(r'$..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${match.value}')
.forEach(print);
}
Data manipulation #
Each JsonPathMatch
produced by the .read()
method contains the .pointer
property which is a valid JSON Pointer
and can be used to alter the referenced value. If you only need to manipulate JSON data,
check out my JSON Pointer implementation.
User-defined functions #
The JSONPath parser may be extended with user-defined functions. The user-defined functions take precedence over the built-in ones specified by the standard. Currently, only functions of 1 and 2 arguments are supported.
To create your own function:
- Import
package:json_path/fun_sdk.dart
. - Create a class implementing either
Fun1
(1 argument) orFun2
(2 arguments).
To use it:
- Create a new JsonPathParser with your function:
final parser = JsonPathParser(functions: [MyFunction()]);
- Use it to parse you expression:
final jsonPath = parser.parse(r'$[?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 argumentindex(<SingularNodeList>)
- returns the index under which the array element is referenced by the parent arraykey(<SingularNodeList>)
- returns the key under which the object element is referenced by the parent objectis_array(<Maybe>)
- returns true if the value is an arrayis_boolean(<Maybe>)
- returns true if the value is a booleanis_number(<Maybe>)
- returns true if the value is a numberis_object(<Maybe>)
- returns true if the value is an objectis_string(<Maybe>)
- returns true if the value is a stringreverse(<Maybe>)
- reverses the stringsiblings(<NodeList>)
- returns the siblings for the nodesxor(<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(@))]');