json_path

Description:

json path

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);
}
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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) or Fun2 (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 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(@))]');
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References #

Standard development
Feature comparison matrix