[Solved] SelectedItem Binding Issue

[develuser]

Hello Telerik,

I think I've found an issue with the RadGridView SelectedItem.
When I bind it to my ViewModel, and set my property, the view never select the row.

Here is a little example to illustrate this :

My ViewModel

public class VisitorsViewModel : NotificationObject {

 

    VisitorViewModel _chuck = new VisitorViewModel() { ID = 2, FirstName = "Chuck", LastName = "Noris" };

    VisitorViewModel _selectedItem;

 

    public VisitorViewModel SelectedItem {

        get { return _selectedItem; }

        set {

            _selectedItem = value;

            RaisePropertyChanged( "SelectedItem" );

        }

    }

 

    public ObservableCollection<VisitorViewModel> Items { get; set; }

 

    public VisitorsViewModel() {

        Items = new ObservableCollection<VisitorViewModel>( new VisitorViewModel [] {

            new VisitorViewModel() { ID = 1, FirstName = "Bruce", LastName = "Lee" },

            _chuck,

            new VisitorViewModel() { ID = 3, FirstName = "Steven", LastName = "Seagal" },

            new VisitorViewModel() { ID = 4, FirstName = "Jean-Claude", LastName = "Van Damme" }

        } );

        SelectedItem = _chuck;

    }

}


My View :

<UserControl x:Class="GridViewSelectedItemTest.MainPage"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"
        mc:Ignorable="d" d:DesignWidth="640" d:DesignHeight="480">
    <Grid x:Name="LayoutRoot">
        <telerik:RadGridView x:Name="gvVisitor" ItemsSource="{Binding Items}" SelectionMode="Single" SelectionUnit="FullRow"
                             SelectedItem="{Binding SelectedItem, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
    </Grid>
</UserControl>

If I want to select the right row, I need to do something like this :

public MainPage() {
    InitializeComponent();
    this.DataContext = new VisitorsViewModel();
    this.Loaded += new System.Windows.RoutedEventHandler( MainPage_Loaded );
}

void MainPage_Loaded( object sender, System.Windows.RoutedEventArgs e ) {
    gvVisitor.SelectedItems.Add( (DataContext as VisitorsViewModel).SelectedItem );
}

Greetings,
Laurent

[Pavel Pavlov]

Hi Laurent,

Can you please clarify - you manipulate a selected items collection , but the selection mode is single . What is the desired result  - binding a single  or persisting multiple selected items in RadGridView.

Regards,
Pavel Pavlov
the Telerik team

[develuser]

Hello Pavel,

Thanks for your quick reply.

I try to bind a single value to the GridView SelectedItem property in order to get the selection on that single row. But the GridView don't select whatever.

My binding

SelectedItem="{Binding SelectedItem, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"

My ViewModel property :

VisitorViewModel _selectedItem;

public VisitorViewModel SelectedItem {
    get { return _selectedItem; }
    set {
        _selectedItem = value;
        RaisePropertyChanged( "SelectedItem" );
    }
}

Greetings,
Laurent

[Pavel Pavlov]

Hello Laurent ,

I have found the problem is related to the fact the selected item is being set at a stage when RadGridView has not yet build its Items collection. Since it can not find it there the first attempt of setting the selected visual fails. Further changes in the ViewModel would be reflected properly.
To avoid duplication I will continue further communication on this matter in your relevant support ticket.

Kind regards,
Pavel Pavlov
the Telerik team

[Rami Abughazaleh]

Hi.

I am experiencing the same issue and I am wondering what needs to be changed to resolve it?

Thank you.

[Rami Abughazaleh]

I was able to resolve the issue by using a custom behavior as described in this blog post:
http://blogs.telerik.com/blogs/posts/10-05-31/how-to-synchronize-your-ui-selected-items-with-your-data-context-using-mvvm-and-blend-behaviors-for-silverlight-and-wpf.aspx