silverlight/windows phone 7 selectedIndex problems with button inside listbox

Question

I've got a listbox with a simple list of items. On my xaml page, I have the following

<ListBox Name="listBox1">
                        <ListBox.ItemTemplate>
                            <DataTemplate>
                                    <TextBlock Text="{Binding firstName}"/>
                                    <TextBlock Text="{Binding lastName}"/>
                                    <Button BorderThickness="0" Click="buttonPerson_Click">
                                        <Image Source="delete-icon.png"/>
                                    </Button>
                                </StackPanel>
                            </DataTemplate>
                        </ListBox.ItemTemplate>
                    </ListBox>

In my codebehind, I try to grab the selectedIndex so I can remove the item from the collection that is bound to my listbox.

private void buttonPerson_Click(object sender, RoutedEventArgs e)
        {

            // If selected index is -1 (no selection) do nothing
            if (listBox1.SelectedIndex == -1)
                return;

            myPersonList.removeAt(listBox1.SelectedIndex);

        }

However, no matter on which row I click the delete button, selectedIndex is always -1

what am I missing?

thanks in advance!

Answer 1

You can do what you want by setting the Tag property of the button to your object like this:

<Button BorderThickness="0" Click="buttonPerson_Click" Tag="{Binding BindsDirectlyToSource=True}">
     <Image Source="delete-icon.png"/>
</Button>

Then in the eventhandler you can do this:

private void buttonPerson_Click(object sender, RoutedEventArgs e)
{
    myPersonList.remove((sender as Button).Tag);
}

Not sure what your Person object is called so I didn't cast the Tag to it, but you will probably have to do that, but looks like you are comfortable with that.

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Is there a missing StackPanel start element in your XAML? This is probably just an oversight, but could cause you some problems if this is your actual code.