Working with JSON

How to:

Dart provides built-in support for JSON with the dart:convert library, making it straightforward to encode and decode JSON. Below are examples showcasing basic operations:

Parsing JSON String to Dart Object:

import 'dart:convert';

void main() {
  // Example JSON string
  String jsonString = '{"name": "John", "age": 30, "email": "[email protected]"}';
  // Decoding JSON to Dart Map
  Map<String, dynamic> user = jsonDecode(jsonString);
  print('Hello, ${user['name']}! You are ${user['age']} years old.');
  // Output: Hello, John! You are 30 years old.

Encoding Dart Object to JSON String:

import 'dart:convert';

void main() {
  // Example Dart object
  Map<String, dynamic> user = {
    'name': 'Jane',
    'age': 25,
    'email': '[email protected]'
  // Encoding Dart Map to JSON
  String jsonString = jsonEncode(user);
  // Output: {"name":"Jane","age":25,"email":"[email protected]"}

Using json_serializable for Complex Models: For complex data models, manual serialization can be cumbersome. The json_serializable package automates this process. It requires additional setup, including adding dependencies to your pubspec.yaml and creating build files. After setup, you can use it as follows:

  1. Define a model with annotations:
import 'package:json_annotation/json_annotation.dart';

part 'user.g.dart';

class User {
  String name;
  int age;
  String email;
  User({required this.name, required this.age, required this.email});
  factory User.fromJson(Map<String, dynamic> json) => _$UserFromJson(json);
  Map<String, dynamic> toJson() => _$UserToJson(this);
  1. Generate the serialization boilerplate: Use the build runner command to generate the user.g.dart file:
flutter pub run build_runner build
  1. Use your model:
void main() {
  // Parsing JSON to User
  Map userMap = jsonDecode('{"name": "John", "age": 30, "email": "[email protected]"}');
  User user = User.fromJson(userMap);
  print('User: ${user.name}, Age: ${user.age}');
  // Output: User: John, Age: 30

  // Converting User back to JSON
  String jsonString = jsonEncode(user.toJson());
  // Output: {"name":"John","age":30,"email":"[email protected]"}

These examples illustrate basic and advanced JSON interactions in Dart, empowering developers to handle data serialization tasks in their applications seamlessly.