class DatabaseHelperForMeasurements{
  static Database db_instance;
  final String TABLE_NAME = "Measurements";

  Future<Database> get db async{
    if(db_instance == null)
      db_instance = await initDB();
    return db_instance;
  }
  initDB() async {
    io.Directory documentsDirectory = await getApplicationDocumentsDirectory();
    String path = join(documentsDirectory.path,"Measurements_db.db");
    var db = await openDatabase(path,version: 1, onCreate: onCreateFunc);
    return db;
  }

  void onCreateFunc(Database db, int version) async{

    await db.execute('CREATE TABLE $TABLE_NAME(id INTEGER PRIMARY KEY AUTOINCREMENT, typeOfMuscle TEXT, numberOfMuscle TEXT);');

  }

  Future<List<MeasurementsDatabaseModel>> getMeasurementsDatabaseModel() async{
    var db_connection = await db;
    List<Map> list = await db_connection.rawQuery('SELECT * FROM $TABLE_NAME');
    List<MeasurementsDatabaseModel> modelList = new List();
    for(int i = 0; i < list.length; i++){
      MeasurementsDatabaseModel measurementsDatabaseModel = new MeasurementsDatabaseModel();
      measurementsDatabaseModel.id = list[i]['id'];
      measurementsDatabaseModel.typeOfMuscle = list[i]['typeOfMuscle'];
      measurementsDatabaseModel.numberOfMuscle = list[i]['numberOfMuscle'];

      modelList.add(measurementsDatabaseModel);
    }
    return modelList;
  }
  void getMeasurementsData (String typeOfMuscle, String numberOfMuscle, int id) async{
    var db_connection = await db;
    String query =
        'GET $TABLE_NAME SET typeOfMuscle ='$typeOfMuscle', numberOfMuscle ='$numberOfMuscle' WHERE id =$id';
    await db_connection.transaction((transition) async{
      return await transition.rawQuery(query);
    });
  }

  void addNewMeasurementsDatabaseModel(MeasurementsDatabaseModel measurementsDatabaseModel) async {
    var db_connection = await db;
    String query =
        'INSERT INTO $TABLE_NAME(typeOfMuscle, numberOfMuscle) VALUES( '${measurementsDatabaseModel.typeOfMuscle}','${measurementsDatabaseModel.numberOfMuscle}')';
    await db_connection.transaction((transition) async{
      return await transition.rawInsert(query);
    });
  }
  void updateMeasurementsDatabaseModel(MeasurementsDatabaseModel measurementsDatabaseModel) async {
    var db_connection = await db;
    String query =
        'UPDATE $TABLE_NAME SET typeOfMuscle ='${measurementsDatabaseModel.typeOfMuscle}', numberOfMuscle ='${measurementsDatabaseModel.typeOfMuscle}' WHERE id =${measurementsDatabaseModel.id}';
    await db_connection.transaction((transition) async{
      return await transition.rawQuery(query);
    });
  }
  void deleteMeasurementsDatabaseModel(MeasurementsDatabaseModel measurementsDatabaseModel) async {
    var db_connection = await db;
    String query = 'DELETE FROM $TABLE_NAME WHERE id = ${measurementsDatabaseModel.id}';
    await db_connection.transaction((transition) async{
      return await transition.rawQuery(query);
    });
  }
}

class MeasurementsDatabaseModel{
  int id;
  String typeOfMuscle;
  String numberOfMuscle;
  MeasurementsDatabaseModel();
}

class ListItem extends StatefulWidget {
  String detail;
  int index;
  String data;

  ListItem({Key key, this.detail, this.index, this.data}) : super(key: key);

  @override
  _ListItem createState() => _ListItem(); // здесь что-то подсвечивает, сам не смог разобраться
}
class _ListItem extends State<ListItem>  {
  bool isAppear = false;

  DatabaseHelperForMeasurements databaseHelperForMeasurements = new DatabaseHelperForMeasurements();

  databaseHelperForMeasurements.getMeasurementsData(typeOfMuscle, numberOfMuscle, id); // здесь возникает ошибка

  String typeOfMuscle;
  String numberOfMuscle;


  // какой-то код

  }
}