How to disable deselection of items in ListView? - wpf

Question

I've got
<ListView SelectionMode="Single" SelectedIndex="0" ItemsSource="{Binding AccountViewModels}" SelectedItem="{Binding SelectedItem}" Style="{StaticResource AccountsList}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<LocalViews:AccountView Margin="{StaticResource ControlMargin}" />
</DataTemplate>
</ItemsControl.ItemTemplate>
</ListView>
Is there a way to disable deselection of an item from the ListView (i.e. ctrl+click)? In other words, I don't want the user to be able to de-select an item, but of course it's OK to select another item.

Answer 1

Since this functionality is purely view/control related it should not be implemented in the view model but you could handle the PreviewMouseLeftButtonDown event of the ListBoxItem container like this:
<ListView SelectionMode="Single" SelectedIndex="0" ItemsSource="{Binding AccountViewModels}" SelectedItem="{Binding SelectedItem}" Style="{StaticResource AccountsList}">
<ListBox.ItemContainerStyle>
<Style TargetType="ListBoxItem">
<EventSetter Event="PreviewMouseLeftButtonDown" Handler="ItemPreviewMouseLeftButtonDown" />
</Style>
</ListBox.ItemContainerStyle>
<ItemsControl.ItemTemplate>
<DataTemplate>
<LocalViews:AccountView Margin="{StaticResource ControlMargin}" />
</DataTemplate>
</ItemsControl.ItemTemplate>
</ListView>
private void ItemPreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
ListBoxItem lbi = sender as ListBoxItem;
e.Handled = lbi.IsSelected;
}

Answer 2

One way to handle this would be to use binding and add logic to disallow de-selection in the view model.
From this answer, change the IsSelected as follows:
private bool isSelected;
public bool IsSelected
{
get { return isSelected; }
set
{
if (value && !isSelected)
{
isSelected = value;
RaisePropertyChanged("IsSelected");
}
}
}