I have an error when I tried to run de future: DB_helper().fetchData(),

    Future<List<Scale>>fetchData() async {
    final Database db = await _initDatabase();
    final List<Map<String, dynamic>> queryResult = await db.query(table);
    //inspect(queryResult);
    return queryResult.map((e) => Scale).toList(); //error
  }

CodePudding user response：

In here

return queryResult.map((e) => Scale).toList(); 

You are returning the type Scale instead of the Scale data.

it should be something like this

return queryResult.map((e) => Scale.fromMap(e)).toList(); 

CodePudding user response：

Code Scale

Maybe I need to change something in toMap() line?

    class Scale {
  int id;
  String codigo,
      ubicacion,
      capacidad,
      resolucion,
      unidades,
      marca,
      modelo,
      serie;

  Scale({
    required this.id,
    required this.codigo,
    required this.ubicacion,
    required this.capacidad,
    required this.resolucion,
    required this.unidades,
    required this.marca,
    required this.modelo,
    required this.serie,
  });

  Map<String, dynamic> toMap() {
    return {
      'id': id,
      'codigo': codigo,
      'ubicacion': ubicacion,
      'capacidad': capacidad,
      'resolucion': resolucion,
      'unidades': unidades,
      'marca': marca,
      'modelo': modelo,
      'serie': serie,
    };
  }

  @override
  String toString() {
    return 'Scale{id: $id, codigo: $codigo, ubicacion: $ubicacion, capacidad: $capacidad, resolucion: $resolucion, unidades: $unidades, marca: $marca, modelo: $modelo, serie: $serie}';
  }

  static fromMap(e) {}
}