c# - Wpf CheckedListbox - how to get selected item

Question

I've made a CheckedListbox in xaml using this code:

                    <ListBox Height="340" ItemsSource="{Binding Sections}" SelectedItem="{Binding SelectedSection}">
                    <ListBox.ItemTemplate>
                        <DataTemplate>
                            <CheckBox IsChecked="{Binding IsChecked}" Content="{Binding Path=Item}" />
                        </DataTemplate>
                    </ListBox.ItemTemplate>
                </ListBox>

And its bind to this collection:

public ObservableCollection<CheckedListItem<String>> Sections { get; set; }
private CheckedListItem<String> _selectedSection;
public CheckedListItem<String> SelectedSection
    {
        get { return _selectedSection; }
        set 
        {
            _selectedSection = value; 
            RaisePropertyChanged("SelectedSection"); 
        }
    }

The CheckedListItem class looks like this:

    public class CheckedListItem<T> : INotifyPropertyChanged
    {
    public event PropertyChangedEventHandler PropertyChanged;

    private bool isChecked;
    private T item;

    public CheckedListItem()
    { }

    public CheckedListItem(T item, bool isChecked = false)
    {
        this.item = item;
        this.isChecked = isChecked;
    }

    public T Item
    {
        get { return item; }
        set
        {
            item = value;
            if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs("Item"));
        }
    }


    public bool IsChecked
    {
        get { return isChecked; }
        set
        {
            isChecked = value;
            if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs("IsChecked"));
        }
    }
}

I tried to set a breakpoint in the _selectedSection = value; part of the code but it never gets triggered when i select/deselect an item in the CheckedListBox.

My question is how can I get the selected item every time its selected/deselected ?

Thanks

Answer 1

Change your XAML to

<ListBox Height="340" ItemsSource="{Binding Sections}" SelectedItem="{Binding SelectedSection}">
    <ListBox.ItemTemplate>
        <DataTemplate>
            <ListBoxItem IsSelected="{Binding IsChecked}">
                <CheckBox IsChecked="{Binding IsChecked}" Content="{Binding Path=Item}" />
            </ListBoxItem>
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>

You are probably clicking on the actual textblock control inside the checkbox or the square control which doesn't trigger selectionchanged for a listbox. If you try to click outside the bounds of the rectangle say the whitespace then it will fire.

It'll be more work if you just want the checkbox as the datatemplate since you want to select/deselect listboxitem' based on the checkbox IsChecked property. So just wrap it inside a ListBoxItem and you should be good to go.