How does the json_serializable package let you automatically generate the required fromJson and toJson methods for your own Dart model classes, avoiding needing to write that particular repetitive boilerplate code entirely completely by hand yourself?

The json_serializable package works together with the build_runner code generation tool to automatically generate a genuinely complete, fully correct fromJson factory constructor and a corresponding toJson method directly for a given Dart class simply annotated with @JsonSerializable, meaningfully reducing the total amount of genuinely repetitive, error prone manual serialization boilerplate code you would otherwise genuinely need to write and separately maintain completely by hand yourself, particularly valuable for a model class containing a genuinely large number of individual specific fields.

@JsonSerializable()
class User {
  final String name;
  final int age;
  User({required this.name, required this.age});
  factory User.fromJson(Map<String, dynamic> json) => _$UserFromJson(json);
  Map<String, dynamic> toJson() => _$UserToJson(this);
}