.NET 4.x WPF ComboBox Databinding SelectedIndex not working - c#

I'm updating my project from .NET Framework 3.5 to .NET Framework 4.5.1. Everything works, except my databinding to a ComboBox. The ComboBox is part of a Itemscontrol. The XAML code:
<ItemsControl x:Name="AfmetingenLijst" BorderBrush="{DynamicResource {x:Static SystemColors.ActiveBorderBrushKey}}" BorderThickness="0" VerticalContentAlignment="Bottom" >
<ItemsControl.ItemTemplate>
<DataTemplate>
<Grid Margin="5,5,5,5">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="2*" />
<ColumnDefinition Width="2*" />
<ColumnDefinition Width="2*" />
<ColumnDefinition Width="2*" />
<ColumnDefinition Width="2*" />
<ColumnDefinition Width="1*" />
</Grid.ColumnDefinitions>
<TextBox Grid.Column="0" Text="{Binding Lengte}" Tag="{Binding LID}" Margin="5,5,5,5" TextChanged="UpdateList"/>
<TextBox Grid.Column="1" Text="{Binding Breedte}" Tag="{Binding BID}" Margin="5,5,5,5" TextChanged="UpdateList"/>
<TextBox Grid.Column="2" Text="{Binding Hoogte}" Tag="{Binding HID}" Margin="5,5,5,5" TextChanged="UpdateList"/>
<TextBox Grid.Column="3" Text="{Binding Naam}" Margin="5,5,5,5" />
<ComboBox Grid.Column="4" ItemsSource="{Binding Path=items}" SelectedIndex="{Binding geselecteerdProduct}" SelectedValuePath="Code" DisplayMemberPath = "Naam" SelectionChanged="UpdateList" Height="25" HorizontalAlignment="Stretch" VerticalAlignment="Center"></ComboBox>
<Button Tag="{Binding ID}" Grid.Column="5" Margin="5,5,5,5" Content="{Binding Title}" Click="Afmeting_handler" />
</Grid>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
In C# a list is filled with the databinding values:
afm = new List<Afmeting>();
if (afm.Count == 0)
{
afm.Add(new Afmeting() { ID = "+", LID = "L+", BID = "B+", HID = "H+", Title = "+", items = items });
afm[afm.Count - 1].geselecteerdProduct = 0;
afmetingen_counter++;
}
AfmetingenLijst.ItemsSource = afm;
The items in the ComboBox exists, I can select them by mouse. But by default SelectedIndex = -1. But in the list "geselecteerdProduct" (the databinding to SelectedIndex) is set to 0.
In .NET 3.5 it is working perfect, but in 4.x SelectedIndex and the value in "afm" is automatically set to -1.
Items is not empty, there are +- 5 items in the list.
Can someone help me?

I think this is a bug for WPF.
When ComboBox is nested in ItemsControl, and set SelectedIndex and SelectedValuePath at the same time, ComboBox's OnSelectionChanged will be fired tiwce at initialize, but SelectionChanged only once.
WPF ComboBox SelectedIndex debug:
To solve the problem is simple, just remove SelectedValuePath from the ComboBox.
XAML:
<ItemsControl x:Name="AfmetingenLijst" BorderBrush="{DynamicResource {x:Static SystemColors.ActiveBorderBrushKey}}" BorderThickness="0" VerticalContentAlignment="Bottom" >
<ItemsControl.ItemTemplate>
<DataTemplate>
<Grid Margin="5,5,5,5">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="2*" />
<ColumnDefinition Width="2*" />
<ColumnDefinition Width="2*" />
<ColumnDefinition Width="2*" />
<ColumnDefinition Width="2*" />
<ColumnDefinition Width="1*" />
</Grid.ColumnDefinitions>
<TextBox Grid.Column="0" Text="{Binding Lengte}" Tag="{Binding LID}" Margin="5,5,5,5" TextChanged="UpdateList"/>
<TextBox Grid.Column="1" Text="{Binding Breedte}" Tag="{Binding BID}" Margin="5,5,5,5" TextChanged="UpdateList"/>
<TextBox Grid.Column="2" Text="{Binding Hoogte}" Tag="{Binding HID}" Margin="5,5,5,5" TextChanged="UpdateList"/>
<TextBox Grid.Column="3" Text="{Binding Naam}" Margin="5,5,5,5" />
<ComboBox Grid.Column="4"
ItemsSource="{Binding Path=items}"
SelectedIndex="{Binding geselecteerdProduct}"
DisplayMemberPath = "Naam"
SelectionChanged="UpdateList"
Height="25"
HorizontalAlignment="Stretch"
VerticalAlignment="Center">
</ComboBox>
<Button Tag="{Binding ID}" Grid.Column="5" Margin="5,5,5,5" Content="{Binding Title}" Click="Afmeting_handler" />
</Grid>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>

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How to bind Observablecollection<T> with combobox in wpf

I am trying to bind Observablecollection<T> with ComboBox. ComboBox having Datatemplete
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ItemsSource="{Binding AdComboBox}"
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<ComboBox.ItemTemplate>
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<Grid.ColumnDefinitions>
<ColumnDefinition Width="1*"/>
<ColumnDefinition Width="1*"/>
<ColumnDefinition Width="1*"/>
</Grid.ColumnDefinitions>
<TextBlock Grid.Column="0"
Text="{Binding Path=LOC, Mode=OneWay}"
Margin="5,0,5,0"/>
<TextBlock Grid.Column="1"
Text="{Binding Path=PUB, Mode=OneWay}"
Margin="0,0,5,0"/>
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Side note: you might want to rename the collection to something more functional instead of AdComboBox. E.g., Ads Because it is not a ComboBox but it is a collection of Ads(?)

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I'd really appreciate any help in the right direction! This seems to be a question that is not easily answered around the web.
#Frederik I've implemented what you've done in the code above using the SelectionChanged event of the ListBox - it still works fine for me.
I've been banging my head against the wall for a bit, but finally managed to solve it. First of all for the ItemTemplate I've made sure that the template is placed in a ListBoxItem element as it follows:
<DataTemplate x:Key="ExpanderViewItems" >
<ListBoxItem DataContext="{Binding}" Tap="ListBoxItem_Tap_1">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="15" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="auto" />
<ColumnDefinition Width="auto" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Image Source="{Binding flagIcon}" Grid.Row="0" Grid.RowSpan="3" Grid.Column="0" />
<TextBlock FontSize="26" Text="{Binding N}" Foreground="Black" FontWeight="Normal" Grid.Row="0" Grid.Column="1"/>
<TextBlock FontSize="20" Text="{Binding RNG}" Foreground="Black" FontWeight="Normal" HorizontalAlignment="Right" Grid.Row="0" Grid.Column="2"/>
<TextBlock FontSize="26" Text="{Binding ValueAndUnit}" Foreground="Black" FontWeight="Medium" HorizontalAlignment="Right" Grid.Row="1" Grid.Column="1" Grid.ColumnSpan="2"/>
<TextBlock FontSize="18" Text="{Binding COM}" Foreground="Black" FontWeight="Normal" Grid.Row="2" Grid.Column="1" Grid.ColumnSpan="2" TextWrapping="Wrap" />
<Line StrokeThickness="1" Stroke="#C4C6CC" Stretch="Fill" X1="0" X2="1" Y1="0" Y2="0" VerticalAlignment="Center" Grid.Row="3" Grid.Column="0" Grid.ColumnSpan="3" />
</Grid>
</ListBoxItem>
</DataTemplate>
Once this is in place, go in the code behind and in the Tap event declared for the ListBoxItem use something like this:
ListBoxItem item = sender as ListBoxItem;
ExpanderItemModel model = item.DataContext as ExpanderItemModel;
Of course, ExpanderItemModel will be whatever you're using for your expander items...
This worked fine for me
Hope this helps!
Good luck!
You can use the "tap" event on the listbox:
In your XAML file add a tap event listner:
<!--Listbox Containing ExpanderViews-->
<ListBox Name="testsList" Grid.Row="3" Grid.Column="0" Tap="testsList_Tap" >
<ListBox.ItemTemplate>
<DataTemplate>
<!--ExpanderView-->
<toolkit:ExpanderView Header="{Binding}"
...
In your code behind file, implement the tap handler:
private void testsList_Tap(object sender, System.Windows.Input.GestureEventArgs e)
{
someModel selectedItem = (someModel)this.testsList.SelectedItem;
// Do something with your seleted data
...
}
you can get the selected values by listbox selectionchanged or expanderview expanded events.
For listbox :
private void lstExams_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
if (e.AddedItems.Count > 0)
{
Model.ExamTitles data = (sender as ListBox).SelectedItem as Model.ExamTitles;
}
}
Here ExamTitles is a class which contains collections
For expanderview Expanded
private void ExpanderView_Expanded(object sender, RoutedEventArgs e)
{
ExpanderView expview = (sender as ExpanderView);
Model.ExamTitles data = expview.Header as Model.ExamTitles;
}
Hope this helps!

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