public ExerciseSetModel addSetTo(TrainingExerciseModel model, int numberOfRepeats) {

    ArrayList<ExerciseSets> existingSets = exerciseSetsDao.getAllForExercise(model.getId());

    Exercise origEx = exerciseDao.getById(model.getExerciseId());
    Training origTr = trainingDao.getById(model.getTrainingId());

    ExerciseSets set = new ExerciseSets();
    set.setNumberOfRepeats(numberOfRepeats);
    set.setTrainingsExercisesId(model.getId());
    set.setOrder(existingSets.size() + 1);

    ExerciseSets saved = exerciseSetsDao.save(set);

    if (saved != null) {
      ExerciseSetModel exerciseSetModel = new ExerciseSetModel();
      exerciseSetModel.setId(saved.getId());
      exerciseSetModel.setNumberOfRepeats(saved.getNumberOfRepeats());
      exerciseSetModel.setOrder(saved.getOrder());
      exerciseSetModel.setTrainingsExercisesId(saved.getTrainingsExercisesId());
      return exerciseSetModel;
    }

    return null;
  }