Two-way Binding. Avoiding change of CurrentItem and its representation in Breadcrumb.

[Ilya]

Hi.

I have the following code in ViewModel:

  private ITileItemModel _currentItem;
        public ITileItemModel CurrentItem
        {
            get
            {
                return _currentItem;
            }
            set
            {
                if (_currentItem == value) return;
                if (func()) return;
                _currentItem = value;
                RaisePropertyChanged(() => CurrentItem);
            }
        }

For RaisePropertyChanged I have redefinition, so it will work fine.

The *,xaml is as following:

<telerik:RadBreadcrumb x:Name="NavigationBreadcrumb"
                               HorizontalAlignment="Stretch" VerticalAlignment="Top"
                               TextModePath="TilePath"
                               IsTextModeEnabled="False"
                               HeaderMemberPath="Header"
                               HierarchicalItemsSource="Children"
                               HierarchicalMemberPath="Header"
                               IsHistoryEnabled="False"
                               Header="{Binding Root}"
                               ItemsSource="{Binding Root.Children}"
                               CurrentItem="{Binding CurrentItem, Mode=TwoWay}"
                               >
             </telerik:RadBreadcrumb>

If  func() returns true I am not changing CurrentItem, but the breadcrumb shows the item I have selected in it. And I have situation with different values in breadcrumb and CurerntItem.

Could you help me to resolve this issue?

Best regards,
Ilya.

[Zarko]

Hello Ilya,
As far as I understand you want to prevent the selection of a specific item, is that right ? There are two ways to do this:
- you could bind the IsEnabled property of the RadBreadcrumbBarItems to some property in your business object (e.g. CanSelect).
- you could add some custom login in your viewModels:

if (func())
{
    this.Path = this.previousPath;
    return;
}

(in MainViewModel)

public bool IsSelected
{
    get
    {
        return this.isSelected;
    }
    set
    {
        if (this.isSelected != value)
        {
            if (Func()) return;

            this.isSelected = value;
            this.OnPropertyChanged("IsSelected");
        }
    }
}

(in your business item)
I've attached a sample project which shows both approaches so could you please examine it and if you have further questions feel free to ask. (Note: the is isEnabled style setter is commented out by default).

Regards,
Zarko
Telerik