public void Filter() { if (SelectedFestivaldate == null && SelectedStage != null) { LineUpList = LineUp.GetLineUpByStageID(SelectedStage.ID); } else if (SelectedFestivaldate != null && SelectedStage == null) { LineUpList = LineUp.GetLineUpByDateID(SelectedFestivaldate.ID); } else if (SelectedFestivaldate != null && SelectedStage != null) { LineUpList = LineUp.GetLineUpByStageAndDateID(SelectedStage.ID, SelectedFestivaldate.ID); } }