Binding ListBos ItemSource to Combobox's selectedVAlue - wpf

Question

I have a ComboBox which is Binded to a List<String> defined in the ViewModel.
I have as well a ListBox who's ItemSource depends on SelectedValue from the ComboBox.
In the ViewModel, I have the following properties:
List<String> ComboBoxSource
string SelectedValue (ComboBox selected value)
ObservableCollection<String> ListBoxSource
Now, when the ComboBox selectedvalue changes, I am setting the SelectedVAlue property in the ViewModel(DataContext) explicitly which is raising a PropertyChange Event on ListBoxSource in order to update the ListBox.
My question is how can I do this without explicitly setting SelectedVAlue in ViewModel i.e Can I bind the ComboBox.SelectedVAlue to my SelectedVAlue property ?
Here is my XAML:
<ComboBox Grid.Column="0" Grid.Row="0" x:Name="ComboBoxVersions" SelectedIndex="0" Margin="10" SelectionChanged="ComboBoxVersions_OnSelectionChanged" ItemsSource="{Binding EnvironmentVersions}">
<ComboBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Text="Version " />
<TextBlock Text="{Binding}" />
</StackPanel>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
<ListBox x:Name="ListBoxEnvironments" Grid.Column="0" Grid.Row="1" Height="300" Grid.ColumnSpan="2" HorizontalAlignment="Stretch" Margin="10" SelectionMode="Multiple" ItemsSource="{Binding Environments}">
<ListBox.ItemsPanel>
<ItemsPanelTemplate>
<WrapPanel Orientation="Horizontal" HorizontalAlignment="Left" Width="800" >
</WrapPanel>
</ItemsPanelTemplate>
</ListBox.ItemsPanel>
<ListBox.ItemTemplate>
<DataTemplate>
<CheckBox x:Name="CheckBoxEnvironment" Content="{Binding}" IsChecked="{Binding RelativeSource={RelativeSource AncestorType={x:Type ListBoxItem}}, Path=IsSelected}" Margin="5">
</CheckBox>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
Here is the Code Behind:
/// <summary>
/// Handles the OnSelectionChanged event of the ComboBoxVersions control.
/// </summary>
/// <param name="sender">The source of the event.</param>
/// <param name="e">The <see cref="SelectionChangedEventArgs"/> instance containing the event data.</param>
private void ComboBoxVersions_OnSelectionChanged(object sender, SelectionChangedEventArgs e)
{
var dataContext = this.DataContext as TestRunnerControlViewModel;
dataContext.SelectedVersion = ((ComboBox) sender).SelectedValue.ToString();
}

Answer 1

Use SelectedItem instead of SelectedValue because it is more appropriate to bind, just create a SelectedVersion property, bind this property to the combobox's SelectedItem, whenever the SelectedItem is changed, update you ListBox itemSource in the setter of that property.
INotifyPropertyChanged interface is necessary to let the ListBox know that their source has been changed
private List<String> _environmentVersions;
public List<String> EnvironmentVersions
{
get
{
return _environmentVersions;
}
set
{
if (_environmentVersions == value)
{
return;
}
_environmentVersions = value;
OnPropertyChanged();
}
}
private ObservableCollection<String> _environments ;
public ObservableCollection<String> Environments
{
get
{
return _environments;
}
set
{
if (_environments == value)
{
return;
}
_environments = value;
OnPropertyChanged();
}
}
private String _selectedVersion ;
public String SelectedVersion
{
get
{
return _selectedVersion;
}
set
{
if (_selectedVersion == value)
{
return;
}
_selectedVersion = value;
//update your listBox itemSource
// ...
}
}
and in the Xaml:
<ComboBox Grid.Column="0" Grid.Row="0" x:Name="ComboBoxVersions" SelectedIndex="0" Margin="10" SelectedItem="{Binding SelectedVersion}" ItemsSource="{Binding EnvironmentVersions}">
<ComboBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Text="Version " />
<TextBlock Text="{Binding}" />
</StackPanel>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>