SelectedItem reset when unloading?

[runer]

I have a RadAutoCompleteBox in RadGridView CellEditTemplate

public class AutoCompleteCell : RadAutoCompleteBox
{
    public AutoCompleteCell()
    {
        SelectionMode = AutoCompleteSelectionMode.Single;
        Unloaded += unloaded;
        Loaded += loaded;
    }

    private void loaded(object sender, RoutedEventArgs e)
    {
        //all has value
        string searchText = SearchText;
        object selectedItem = SelectedItem;
    }

    private void unloaded(object sender, RoutedEventArgs e)
    {
        string searchText = SearchText; //has value
        object selectedItem = SelectedItem; //no value
    }
}

 

SearchText is in dropdown ItemsSource, when I click the cell and enter edit mode, Loaded event fired and both SearchText and SelectedItem has value, but when I just press Esc to exit edit mode and in Unloaded event, SearchText still has value but SelectedItem is null.

Why this happened and how to fix it? Thanks.

<controls:AutoCompleteCell SelectedItem="{Binding Value, Mode=TwoWay}"  ItemsSource="{Binding Source, Mode=OneWay}" SearchText="{Binding Header, Mode=OneWay}" />

 

"Header" is returned from "Value".

 

 

 

[Martin]

Hi,

I investigated the cause for this behavior and traced it down to a timing issue at the framework binding mechanism. By default, RadAutoCompleteBox clears its selection upon resetting the ItemsSource which in this particular case occurs before the control is unloaded and thus - through the two-way binding the SelectedItem property in your ViewModel is set to null. 

What I can suggest in this case is to explicitly set the DataContext of the control like so:

<telerik:RadAutoCompleteBox
ItemsSource="{Binding Countries}"

DataContext="{Binding}"

DisplayMemberPath="Name"

Unloaded="RadAutoCompleteBox_Unloaded"

Loaded="RadAutoCompleteBox_Loaded"

SelectedItem="{Binding SelectedCountry, Mode=TwoWay}"

SearchText="{Binding Name, Mode=TwoWay}"

SelectionMode="Single"/>

Regards,
Martin Vatev
Progress Telerik