Làm việc với JSON trong Dart

import 'dart:convert';

import 'dart:convert';
 
void main() {
  String jsonString = '{"name": "Alice", "age": 25}';
  
  Map<String, dynamic> data = jsonDecode(jsonString);
  print(data['name']);  // Alice
  print(data['age']);   // 25
}

import 'dart:convert';
 
void main() {
  Map<String, dynamic> data = {
    'name': 'Bob',
    'age': 30,
    'hobbies': ['reading', 'gaming'],
  };
  
  String jsonString = jsonEncode(data);
  print(jsonString);
  // {"name":"Bob","age":30,"hobbies":["reading","gaming"]}
}

import 'dart:convert';
 
class User {
  String name;
  int age;
  String email;
  
  User(this.name, this.age, this.email);
  
  // fromJson factory
  factory User.fromJson(Map<String, dynamic> json) {
    return User(
      json['name'],
      json['age'],
      json['email'],
    );
  }
  
  // toJson method
  Map<String, dynamic> toJson() {
    return {
      'name': name,
      'age': age,
      'email': email,
    };
  }
}
 
void main() {
  // Parse JSON to object
  String jsonString = '{"name":"Alice","age":25,"email":"alice@email.com"}';
  var user = User.fromJson(jsonDecode(jsonString));
  
  // Object to JSON
  print(jsonEncode(user.toJson()));
}

import 'dart:convert';
 
void main() {
  String jsonArray = '[{"name":"Alice"},{"name":"Bob"}]';
  
  List<dynamic> list = jsonDecode(jsonArray);
  
  for (var item in list) {
    print(item['name']);
  }
}

import 'dart:convert';
 
class Address {
  String city;
  String country;
  
  Address(this.city, this.country);
  
  factory Address.fromJson(Map<String, dynamic> json) {
    return Address(json['city'], json['country']);
  }
  
  Map<String, dynamic> toJson() => {'city': city, 'country': country};
}
 
class Person {
  String name;
  Address address;
  
  Person(this.name, this.address);
  
  factory Person.fromJson(Map<String, dynamic> json) {
    return Person(
      json['name'],
      Address.fromJson(json['address']),
    );
  }
  
  Map<String, dynamic> toJson() => {
    'name': name,
    'address': address.toJson(),
  };
}

import 'dart:convert';
 
void main() {
  var data = {'name': 'Alice', 'hobbies': ['a', 'b']};
  
  var encoder = JsonEncoder.withIndent('  ');
  print(encoder.convert(data));
  /*
  {
    "name": "Alice",
    "hobbies": [
      "a",
      "b"
    ]
  }
  */
}

import 'dart:convert';
 
T? tryParseJson<T>(String json, T Function(dynamic) parser) {
  try {
    return parser(jsonDecode(json));
  } catch (e) {
    print('JSON parse error: $e');
    return null;
  }
}
 
void main() {
  String json = '{"name": "Alice"}';
  var user = tryParseJson(json, (data) => User.fromJson(data));
}

import 'dart:io';
import 'dart:convert';
 
Future<void> main() async {
  var file = File('data.json');
  String content = await file.readAsString();
  var data = jsonDecode(content);
  print(data);
}