CODEWITHSUNDEEP
wpfbindingtabcontrol
Morgan M.
Morgan M.

Reputation: 856

Strange behavior with two-way Binding and TabControl

In my application, I have the following TabControl:

<TabControl ItemsSource="{Binding MyItemsSource}"
            ContentTemplate="{StaticResource ResourceKey=MyContentTemplate}"
            IsSynchronizedWithCurrentItem="True" />

Here is the ContentTemplate used:

<DataTemplate x:Key="MyContentTemplate">
    <Canvas>
        <TextBox Text="{Binding Path=MyFirstText, Mode=TwoWay}" />
        <TextBox Text="{Binding Path=MySecondText, Mode=TwoWay}" />
    </Canvas>
</DataTemplate>

And the ItemsSource:

public ObservableCollection<MyData> MyItemsSource { get; set; }

public class MyData
{
    public string MyFirstText { get; set; }
    public string MySecondText { get; set; }
}

Please consider this scenario:

Another scenario:

Is that a normal behavior? Or am I doing something wrong? Thank you.

Upvotes: 2

Views: 549

Answers (3)

Derrick Moeller
Derrick Moeller

Reputation: 4950

The issue is that LostFocus isn't fired when changing tabs, you can change the UpdateSourceTrigger to PropertyChanged as previously mentioned, but I preferred extending TabControl and firing LostFocus manually. This way I don't have to add UpdateSourceTrigger=PropertyChanged to every TextBox in my Tab. I also avoid updating the viewmodel with every key press.

This is a derivative of the solution mentioned here. WPF: Data bound TabControl doesn't commit changes when new tab is selected

public class SmartTabControl : TabControl
{
    protected override void OnSelectionChanged(SelectionChangedEventArgs e)
    {
        if (Keyboard.FocusedElement is TextBox)
            Keyboard.FocusedElement.RaiseEvent(new RoutedEventArgs(LostFocusEvent));

        base.OnSelectionChanged(e);
    }
}

Upvotes: 0

VidasV
VidasV

Reputation: 4895

It may be related to a focused element and OnLostFocus event being not fired when switching between tabs. Try altering your bindings with UpdateSourceTriger attribute like this:

<DataTemplate x:Key="MyContentTemplate">
    <Canvas>
        <TextBox Text="{Binding Path=MyFirstText, UpdateSourceTrigger=PropertyChanged}" />
        <TextBox Text="{Binding Path=MySecondText, UpdateSourceTrigger=PropertyChanged}" />
    </Canvas>
</DataTemplate>

Also, you do not need to specify twoway mode as in wpf it is the default one.

Upvotes: 1

CKII
CKII

Reputation: 1486

It happens because TextBox's update trigger is set to LostFocus by default. Change it to PropertyChanged, and it should work:

<TextBox Text="{Binding Path=MyFirstText, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />

UpdateSourceTrigger: http://msdn.microsoft.com/en-us/library/system.windows.data.updatesourcetrigger.aspx

Upvotes: 2

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