Question

I’m using a ListBox to display all values contained in Dictionary<> object:

<ListBox Height="519" x:Name="ContactsListBox" Width="460" Margin="0,0,0,0" SelectionChanged="ContactsListBox_SelectionChanged">
        <ListBox.ItemTemplate>
            <DataTemplate>
                <StackPanel Orientation="Vertical">
                    <TextBlock Text="{Binding Key}" Margin="5" Foreground="{StaticResource PhoneAccentBrush}"/>
                    <TextBlock x:Name ="LastNameData" Text="{Binding Value}" Margin="20, 0" />
                </StackPanel>
            </DataTemplate>
        </ListBox.ItemTemplate>
</ListBox>

Content is filled by the following code:

Dictionary<long, Contact> contacts = new Dictionary<long, Contact>();
this.ContactsListBox.ItemsSource = contacts;

Now, I would like to ‘know’ which specific “Contact” in ListBox is currently selected, either by knowing its Key, or just by extracting value from “LastNameData” TextBlock.

I tried doing something like that, but obviosly it doesn’t work:

private void ContactsListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    ListBox lb = this.ContactsListBox.SelectedItem as ListBox;
    this.Test_SomeOtherTextBlock.Text = lb.ToString();
}

I would really appreciate your help!

Answer 1

There are several problems:

In Xaml you probably don’t want to display the class name, but a reasonable string, for example:

<TextBlock x:Name ="LastNameData" Text="{Binding Value.LastName}" Margin="20, 0" />

In the selection processing the selected item is KeyValuePair<…>. You could easily find it yourself, if you looked at the returned type in debugger. (Should be kind of a reflex for a programmer, hence a questions like above should never appear :))

private void ContactsListBox_SelectionChanged(object sender, SelectionChangedEventArgs e) { 
    KeyValuePair<long, Contact> kv = (KeyValuePair<long, Contact>)this.ContactsListBox.SelectedItem;
    Contact c = (Contact)kv.Value;
    Debug.WriteLine(c.LastName);
}