Làm việc với JSON

🎯 Mục tiêu: Parse và encode JSON.

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💡 dart:convert

import 'dart:convert';

// JSON String → Map
var jsonString = '{"name": "Alice", "age": 25}';
var map = jsonDecode(jsonString);
print(map['name']);  // Alice

// Map → JSON String
var json = jsonEncode({'name': 'Bob', 'age': 30});
print(json);  // {"name":"Bob","age":30}

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📝 JSON ↔ Class

class User {
  final String name;
  final int age;

  User({required this.name, required this.age});

  factory User.fromJson(Map<String, dynamic> json) {
    return User(
      name: json['name'],
      age: json['age'],
    );
  }

  Map<String, dynamic> toJson() => {
    'name': name,
    'age': age,
  };
}

// Usage
var user = User.fromJson(jsonDecode(jsonString));
var json = jsonEncode(user.toJson());

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📱 Trong Flutter - HTTP

Future<User> fetchUser() async {
  final response = await http.get(Uri.parse('api/user/1'));

  if (response.statusCode == 200) {
    return User.fromJson(jsonDecode(response.body));
  } else {
    throw Exception('Failed to load user');
  }
}

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✅ Checklist

• jsonDecode để parse
• jsonEncode để stringify
• Tạo fromJson và toJson cho models

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