Command binding doesn't function if its inside an item template of a listbox

Question

I have the following user control

<ListBox   ItemsSource="{Binding Persons}" 
           SelectedItem="{Binding SelectedPerson}" 
           VerticalAlignment="Top" Width="166" >
            <ListBox.Template>
                <ControlTemplate>
                    <StackPanel >
                        <ItemsPresenter/>
                        <Button Content="Add" Background="Transparent" Command="{Binding NewItemCommand}"/>
                    </StackPanel>
                </ControlTemplate>
            </ListBox.Template>

            <ListBox.ItemTemplate>
                <DataTemplate>
                    <StackPanel Orientation="Horizontal">
                        <Button  Height="16" Width="16" Background="Transparent" Command="{Binding DeleteItemCommand}">
                            <Image Source="images/delete-icon.png" />
                        </Button>
                        <TextBlock Text="{Binding Name}"/>
                    </StackPanel>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>

and i have a view model for it with two commands, the first command that you can see above NewItemCommand is working fine, how ever the second command DeleteItemCommand doesn't function.

is it because its in the item template?

sa_ddam213 · Accepted Answer · 2013-10-14 03:38:08Z

2

Yes, this is because the DataContext for the ItemTemplate is the Item from Persons not the ViewModel

To bind the DeleteItemCommand on each item you will need to bind back to the ViewModel that is holding the command

Example, binding to the DataContext of the ListBox

<Button Command="{Binding Path=DataContext.DeleteItemCommand, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ListBox}}}" />

Edit:

If you want to remove the item that the button was clicked on you can pass the item the button belongs to as the CommandParameter and handle that in your comman, Not sure what type of command you are using but this is simple if you are using RelayCommand or DelegateCommand

 <Button Command="{Binding Path=DataContext.DeleteItemCommand, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ListBox}}}"
         CommandParameter="{Binding}" />

public MainWindow()
{
    InitializeComponent();
    DeleteItemCommand = new RelayCommand(person => DeletePerson(person as Person));
}

private void DeletePerson(Person person)
{
    Collection.Remove(person);
}

edited Oct 14, 2013 at 3:38

answered Oct 14, 2013 at 3:23

sa_ddam213

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2 Comments

FPGA Over a year ago

perfect thanks, any idea on how would you remove an item from the collection? my delete command deletes the selected item , however the item doesnt get the focused if i click its remove button without focusing it first

sa_ddam213 Over a year ago

You could pass the Item as the CommandParameter and remove it from the collection

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