.fromJson & .toJson example in Dart

main.dart

// .fromJson , .toJson example in Dart
// .fromJson convert a Map Object to an Instance
// .toJson convert an Instance to a Map Object
class Person {
  Person({required this.name, required this.age});
  String name;
  int age;

  factory Person.fromJson(Map<String, Object> json) {
    final name = json['name'];
    final age = json['age'];
    if (name == null) {
      throw UnimplementedError('Key name unimplemented');
    }
    if (age == null) {
      throw UnimplementedError('Value age unimplemented');
    }

    if (name is String && age is int) {
      return Person(name: name, age: age);
    }
    throw UnsupportedError('Invalid type name');
  }

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

void main() {
  var the_json_in_map = {
    'name': 'Lucy',
    'age': 48,
  };
  var person = Person.fromJson(the_json_in_map);
  print(person);
  var json = person.toJson();
  print(json);
}