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AutoCompleteBox SelectedItems Binding problem

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AutoCompleteBox

This is a migrated thread and some comments may be shown as answers.

Marcelo asked on 14 Feb 2013, 03:18 PM

Hi,

I have a Listbox with a datatemplate:

<DataTemplate x:Key="ListBoxDataTemplate">

<StackPanel Orientation="Horizontal">

<TextBlock Text="{Binding FieldName, Mode=TwoWay}" Width="120" />

<telerik:RadAutoCompleteBox Width="197" Name="autoCompBox"

Background="Beige" SelectionMode="Multiple" TextSearchMode="StartsWith"

TextSearchPath="Code" AutoCompleteMode="Suggest"

DropDownItemTemplate="{StaticResource ContactSearchTemplate}" DataContext="{Binding}"

ItemsSource="{Binding DataContext.Codes, Mode=TwoWay, RelativeSource={RelativeSource AncestorType=telerik:RadListBox}}"

SelectedItems="{Binding Path=AssociatedCodes, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}">

</telerik:RadAutoCompleteBox>

</StackPanel>

</DataTemplate>

My ListBox ItemsSource property is binded to a property in ViewModel named:

public List<ReportDataAssociation> ReportDataAssociation

{

get { return m_reportDataAssociation; }

set { m_reportDataAssociation = value; OnPropertyChanged("ReportDataAssociation"); }

}

This property is an object with the following properties:

string FieldName;

ObservableCollection<ReportCodes> AssociatedCodes;

The FieldName is binded to the TextBlock
The AssociatedCodes is binded to the SelectedItemsProperty of each AutoCompleteBox.

I load an ObservableCollection<ReportCodes> named Codes which is binded to all AutoCompleteBoxes.
The AssociatedCodes is a property of ReportDataAssociation which is binded to SelectedItems.
Any ReportCode I add to the AssociatedCodes' List is from the ObservableCollection<ReportCodes> named Codes
so the referece to the object is the same.

The problem is:
When I select or delete some items from some autocompletebox,
the property AssociatedCodes does not change.
When I change the property AssociatedCodes at runtime, the selectedItems in autocompletebox
don't change.
I think it's a binding problem but i can't figure out what it is.
Maybe because the AutoCompleteBoxes are in a template.

I tried to bind the selectedItems in many ways, the binding shown above is one of my many tries..
Please help
Thanx in advance

18 Answers, 1 is accepted

answered on 23 May 2013, 08:02 AM

Hi again,

I bypass the issue using blend.

in the XAML:
<i:Interaction.Triggers>
<i:EventTrigger EventName="SelectionChanged">
<i:InvokeCommandAction Command="{Binding SelectionChangedCommand}"
CommandParameter="{Binding SelectedItems, ElementName=elementsCompleteBox}"/>
</i:EventTrigger>
</i:Interaction.Triggers>

and in the VM:
public ICommand SelectionChangedCommand { get; set; }
SelectionChangedCommand = new DelegateCommand<ObservableCollection<object>>(UpdateMultiSelect);

private void UpdateMultiSelect(ObservableCollection<object> objects)
{
myModelListSelected = new ObservableCollection<myModel>(objects.Cast<myModel>());
}

answered on 05 Aug 2016, 03:33 PM

Hi Yana,

it was not my intention to become a Telerik Bug-Expert. Since this is a very basic scenario i'm sure you will find someone who will agree to code a repro for you.

Environment:
- Visual Studio 2015 with Update 3
- .NET 4.5
- Telerik WPF Controls 2016.2.613.45.NoXaml

Conditions:
- RadAutoCompleteBox was placed inside a TabControl
- SelectedItems Binding to an ObservableCollection<object>

As soon as you switch tabs and come back to the tab where the RadAutoCompletBox is located the VS debug out will show the error.

System.Windows.Data Error: 2 : Cannot find governing FrameworkElement or FrameworkContentElement for target element. BindingExpression:Path=SelectedItems; DataItem='RadAutoCompleteBox' (Name=''); target element is 'AddItemAdapterCollection' (HashCode=19355258); target property is 'Source' (type 'IEnumerable')

Thanks,
Stefan

answered on 10 Aug 2016, 07:32 AM

Hello Stefan,

I am sorry for my misunderstanding.

Actually this is a known error related to a timing issue in WPF platform. More information can be found in the official social MSDN forums here: http://social.msdn.microsoft.com/Forums/vstudio/en-US/564e7160-df70-4e95-945d-60954dd7a2ae/wpf-binding-errors-systemwindowsdata-error-4?forum=wpf

Such issues should be ignored as they are timing issues in the WPF platform itself and are not critical for runtime. If you would like not to see them in the output after building your project you could use the following workaround:
- In your project's code behind set the DataBindingSource.Switch.Level to Critical. The next code snippet shows the described workaround:
System.Diagnostics.PresentationTraceSources.DataBindingSource.Switch.Level = System.Diagnostics.SourceLevels.Critical;

You could also set IsContentPreserved property of RadTabControl to true, so that the content is not reloaded every time you switch the tabs.

Regards,
Yana
Telerik by Progress

Do you need help with upgrading your AJAX, WPF or WinForms project? Check the Telerik API Analyzer and share your thoughts.

answered on 12 Aug 2016, 02:16 PM

Hi Stefan,

Again, I apologize for the confusion.

The observed behavior is reproducible when the AutoCompleteBox is placed inside the native WPF TabControl. The control is reloading its content each time when the tabs are switching. Because of that the elements from the previously selected tab get removed from the Visual Tree and the one from the newly selected are loaded - the observed error is a timing issue that gets resolved.

What we could suggest you is instead of using the native WPF TabControl to use the one provided by Telerik RadTabControl. It provides a property named IsContentPreserved that by setting it to True prevents the controls from removing from the Visual Tree when switching between the Tabs and the bindings are preserved.

Regards,
Yana
Telerik by Progress

Do you need help with upgrading your AJAX, WPF or WinForms project? Check the Telerik API Analyzer and share your thoughts.