inherit constructor and factory in flutter

Question

I'm learning flutter and I'm trying to turn requests results into more convenient objects, so I created the basic schema of a response (which is not supposed to be instantiated anytime) :

class BaseModel {
  final String id;
  final DateTime createdAt;
  final DateTime updatedAt;
  final String databaseId;
  final String collectionId;

  BaseModel(
      {required this.id,
      required this.createdAt,
      required this.updatedAt,
      required this.databaseId,
      required this.collectionId});

  factory BaseModel.fromMap(Map<String, dynamic> map) {
    return BaseModel(
        id: map['\$id'].toString(),
        collectionId: map['\$collectionId'].toString(),
        createdAt: DateTime.tryParse(map['\$createdAt'].toString())!,
        updatedAt: DateTime.tryParse(map['\$updatedAt'].toString())!,
        databaseId: map['\$databaseId'].toString());
  }
}

I'd like to use this basis to create all the other objects I'll need, but I feel like I'm forced to write some useless code everytime I extend the class :

class ProfilePictureModel extends BaseModel {
  final String userId;
  final Uri pfp;

  ProfilePictureModel(
      {required super.id,
      required super.createdAt,
      required super.updatedAt,
      required super.databaseId,
      required super.collectionId,
      // everything above that has been written already in super class
      required this.userId,
      required this.pfp});

  factory ProfilePictureModel.fromMap(Map<String, dynamic> map) {
    return ProfilePictureModel(
      id: map['\$id'].toString(),
      collectionId: map['\$collectionId'].toString(),
      createdAt: DateTime.tryParse(map['\$createdAt'].toString())!,
      updatedAt: DateTime.tryParse(map['\$updatedAt'].toString())!,
      databaseId: map['\$databaseId'].toString(),
      // everything above that has been written already in super class
      userId: map['user_id'].toString(),
      pfp: Uri.dataFromString(map['pfp_url'].toString()),
    );
  }
}

So here's my question eventually : how can I take advantage of super constructor and factory in this situation ? I felt stuck with setting BaseModel abstract. Maybe am I going on the wrong way ? Thanks already peeps !

Answer 1

You can just directly use the BaseModel as an object instead of using it as a super class.

class BaseModel {
  final String id;
  final DateTime? createdAt;
  final DateTime? updatedAt;
  final String databaseId;
  final String collectionId;

  BaseModel({
    required this.id,
    required this.createdAt,
    required this.updatedAt,
    required this.databaseId,
    required this.collectionId,
  });

  factory BaseModel.fromMap(Map<String, dynamic> map) {
    return BaseModel(
      id: map['id'] as String,
      createdAt: DateTime.tryParse(map['createdAt'].toString()),
      updatedAt: DateTime.tryParse(map['updatedAt'].toString()),
      databaseId: map['databaseId'] as String,
      collectionId: map['collectionId'] as String,
    );
  }
}

class ProfilePictureModel {
  final String userId;
  final String pfp;
  final BaseModel baseModel;

  ProfilePictureModel({
    required this.userId,
    required this.pfp,
    required this.baseModel,
  });


  factory ProfilePictureModel.fromMap(Map<String, dynamic> map) {
    return ProfilePictureModel(
      userId: map['userId'] as String,
      pfp: map['pfp'] as String,
      baseModel: BaseModel.fromMap(map['baseModel'] as Map<String, dynamic>),
    );
  }
}

Note: To create model classes in dart you can use extensions for VsCode or android studio.

-> In VS code just add the "dart data class generator" extension.

-> Create your class and define parameters.

-> Hover over the class name and a bulb icon will appear, then tap on that bulb icon and then some options will visible (like: for data class, constructor, toJson()...).

-> Then tap on "Generate data class".

-> Your data class will be generated.

or you can use: Quicktype