private async void Button_Clicked(object sender, EventArgs e)
        {
            var itemAll = (TreningDetaljiViewModel)((Button)sender).CommandParameter;
            var item    = itemAll.treningDetaljiModel.TreningModel;

            if (item.Ocjena < 1 || item.Ocjena > 5)
            {
                await PopupNavigation.Instance.PushAsync(new PopupView("Error", "Ocjena mora biti izmedju 1 i 5"));
            }
            else
            {
                var clanPrisustvoInsertRequest = new Wellness.Model.Requests.ClanPrisustvoInsertRequest()
                {
                    ClanId       = item.ClanId,
                    Ocjena       = item._Ocjena,
                    Prisustvovao = true,
                    TreningId    = item.Id
                };

                var result = await _apiService_ClanPrisustvo.Update <Wellness.Model.ClanPrisustvo>(item.PrisustvoId, clanPrisustvoInsertRequest);

                await PopupNavigation.Instance.PushAsync(new PopupView("Success", "Uspjesno ste ocijenili trening !"));



                ((Button)sender).IsEnabled = false;
                item.Ocjenjen = true;
            }
        }
        private async void rating_ValueChanged(object sender, Syncfusion.SfRating.XForms.ValueEventArgs e)
        {
            var clanPrisustvoInsertRequest = new Wellness.Model.Requests.ClanPrisustvoInsertRequest()
            {
                ClanId       = model.TreningMod.ClanId,
                Ocjena       = (int)rating.Value,
                Prisustvovao = true,
                TreningId    = model.TreningMod.Id
            };

            var result = await _apiService_ClanPrisustvo.Update <Wellness.Model.ClanPrisustvo>(model.TreningMod.PrisustvoId, clanPrisustvoInsertRequest);

            await PopupNavigation.Instance.PushAsync(new PopupView("Success", "Uspjesno ste ocijenili trening !"));

            rating.ReadOnly = true;
        }