Flutter: _CastError (type 'Null' is not a subtype of type 'String' in type cast)

Question

I am building an app where the user is able to store favorites locally on their device. Therefor I am using the SQFlite package.

Opening the Favorite page I am running the following error:

Exception has occurred. _CastError (type 'Null' is not a subtype of type 'String' in type cast)

This is my model class:

class Model {
  late String name;
  late String description;
  final String imagePath;
  late int id;

  Model({
    required this.name,
    required this.id,
    required this.description,
    required this.imagePath,
  });

  Map<String, dynamic> toMap() {
    return {
      'id': id,
      'name': name,
      'imagePath': imagePath,
      'description': description,
    };
  }
}

And here where the exception occurs:

  Future<List<Model>> getMechanism() async {
    final Database db = await database;

    final List<Map<String, dynamic>> maps = await db.query('fav');
    return List.generate(maps.length, (i) {
      return Model(
        id: maps[i]['id'],
        name: maps[i]['name'] as String,
        imagePath: maps[i]['imagePath'] as String,
        description: maps[i]['description'] as String,
      );
    });
  }

Printing the map variable I receive the following:

flutter: [{id: 1, name: Model, imagePath: null, description: null}]

This is the model class:

  List<Model> model = <Model>[
    Model(
      name: 'Test',
      id: 1,
      imagePath: 'assets/images/model.png',
      description: 'description'
    ),

Edit:

The function adding the items to the favorites database:

  Future initDb() async {
    database = openDatabase(
      join(await getDatabasesPath(), 'fav'),
      onCreate: (db, version) {
        return db.execute(
            "CREATE TABLE fav(id INTEGER PRIMARY KEY, name TEXT, imagePath TEXT, description TEXT)");
      },
      version: 1,
    );
  }

  Future<void> insertEntry(Model model) async {
    final Database db = await database;

    await db.insert(
      'fav',
      model.toMap(),
      conflictAlgorithm: ConflictAlgorithm.replace,
    );
  }

Answer 1

There are no errors found in your code.

You may please check the maps variable with print or log, to see whether the data is valid or not.