class Vehicle { final String id; final String make; final String model; final String color; final String licensePlate; Vehicle({ required this.id, required this.make, required this.model, required this.color, required this.licensePlate, }); String get displayName => '$color $make $model ($licensePlate)'; Vehicle copyWith({ String? make, String? model, String? color, String? licensePlate, }) { return Vehicle( id: id, make: make ?? this.make, model: model ?? this.model, color: color ?? this.color, licensePlate: licensePlate ?? this.licensePlate, ); } Map toJson() => { 'id': id, 'make': make, 'model': model, 'color': color, 'licensePlate': licensePlate, }; factory Vehicle.fromJson(Map json) => Vehicle( id: json['id'] as String, make: json['make'] as String, model: json['model'] as String, color: json['color'] as String, licensePlate: json['licensePlate'] as String, ); }