Reseting SelectedItem ou ItemsSource

[Cristovao]

I'm binding my slideview

<telerikPrimitives:RadSlideView x:Name="radSlideView"
                                          Grid.Row="0"
                                          Grid.RowSpan="2"
                                          ItemsSource="{Binding Items}"
                                          SelectedItem="{Binding DataContext.SelectedPage, ElementName=LayoutRoot,Mode=TwoWay}"
                                          IsLoopingEnabled="True"
                                          ItemTemplateSelector="{StaticResource templateSelector}"
                                          AdjacentItemsPreviewMode="Next">
              <telerikPrimitives:RadSlideView.ItemTemplate>
                  <DataTemplate/>
              </telerikPrimitives:RadSlideView.ItemTemplate>

          </telerikPrimitives:RadSlideView>

But if I try to reset the SelecedItem to Null on my ViewModel I get an error.. or even I try to clear my Items I get an error....
I'm using MVVM Light ..

Any thoughs?








111

[Todor]

Hi Cristovao,

Thank you for writing.

RadSlideView's SelectedItem is the one that is currently displayed. The SelectedItem gets automatically set to the first item of the collection and as long as there are items, one of them is always visible and is "selected". Therefore, if you want to "reset" the SlideView, you should set your property to the first item and not to null.

I hope this information help. Let me know if you need additional assistance.

Regards,
Todor
Telerik

[Cristovao]

I understand that but  there's a scenario that it's not applicable.

1) You are on a list of item 
2) Taping one element you'll navigate to your details in a form of a page with a SlideView
This is ALL done via MVVM binding a ObservableCollection<Page> to the ItemsSource and a Page to the SelectedItem 
3) You press back
4) you select another item from you list navigating to the detais,
5) you MUST clear you  ObservableCollection<Page> before loading the Pages from the selected Item from the previous list.
Here I get and exception that the SelectedPage that is bindind to the SelectedItem Cannot be null

thank you.

[Todor]

Hi Cristovao,

I agree that you may need to clear the collection and this is why you shouldn't get an exception when trying to clear the ItemsSource. The expected exception is when you do have items, but you try to set the selected item to null.

If you get an exception even without setting the SelectedItem to null, please open a new support ticket with attached sample project that we can use to reproduce the issue and we will assist you further.

Regards,
Todor
Telerik

[Cristovao]

I've opened a Ticket..

because all I do is 

  Items = new ObservableCollection<Models.UI.GuideBasePage>();

and if it's the second time I open the page .. it throws an exception


Thanks

[Todor]

Hi Cristovao,

From our communication in the support ticket, it seems like you have managed to clear the items in the view model before SlideView is loaded. This way it is bound to the correct collection from the very beginning and there is no present issue. This thread is considered closed.

Regards,
Todor
Telerik

[Eng]

i bind the selected item from mvvm and it always be null and take the first item always 

[Kiril Stanoev]

Hi Eng,

Could you please elaborate a bit more on the issue you're experiencing? Also, it would be great if you can send us a sample project reproducing the issue.

Regards,
Kiril Stanoev
Telerik

[Eng]

  i have a list of favorites when i navigate to full screen page i want to set the selected item from viewmodel 
  <DataTemplate x:Key="RadSlideViewItemTemplate">
                <telerikSlideView:PanAndZoomImage Stretch="Uniform" Source="{Binding ImagePath, Converter={StaticResource IsoImageCoverter}}"  ZoomMode="Free">
                    <telerikSlideView:PanAndZoomImage.BusyIndicatorStyle>
                        <Style TargetType="telerikPrimitives:RadBusyIndicator">
                            <Setter Property="AnimationStyle" Value="AnimationStyle9"/>
                        </Style>
                    </telerikSlideView:PanAndZoomImage.BusyIndicatorStyle>
                </telerikSlideView:PanAndZoomImage>
            </DataTemplate>
<telerikPrimitives:RadSlideView x:Name="slideView"  IsLoopingEnabled="False"
                                        ItemsSource="{Binding FavouritesList}" 
                                        
                                        SelectedItem="{Binding selectedItem,Mode=TwoWay}"
                                       
                                        ItemTemplate="{StaticResource RadSlideViewItemTemplate}"
                                         >
            
        </telerikPrimitives:RadSlideView>

[Eng]

the selected item in slideview is always null so it display the first item in slide view 

[Kiril Stanoev]

Hello Eng,

Please examine the attached project and let us know if it helps.

Regards,
Kiril Stanoev
Telerik

[Eng]

Thanks Kiril