How to bind listbox in windows phone c#

Question

In my windows phone application, I am want to get contact list and I follow this link http://stackoverflow.com/questions/18387249/selecting-contacts-in-windows-phone-8 and working like below:

public class CustomContact
{
   public string Name { get; set; }
   public string Number { get; set; }

   public CustomContact()
    {
    }


    public CustomContact(Contact contact)
    {
        Name = contact.DisplayName;
        var number = contact.PhoneNumbers.FirstOrDefault();
        if(number != null)
            Number = number.PhoneNumber;
        else
            Number = "";
    }
}

In the above code I am creating class class of CustomContact and below is the xaml.cs page

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Navigation;
using Microsoft.Phone.Controls;
using Microsoft.Phone.Shell;
using GetContacts.Resources;
using Microsoft.Phone.UserData;

namespace GetContacts
{
    public partial class MainPage : PhoneApplicationPage
    {
        // Constructor
        public MainPage()
        {
            InitializeComponent();

            // Sample code to localize the ApplicationBar
            //BuildLocalizedApplicationBar();
        }
        private void ButtonContacts_Click(object sender, RoutedEventArgs e)
        {
            Contacts cons = new Contacts();
            cons.SearchCompleted += new EventHandler<ContactsSearchEventArgs>(Contacts_SearchCompleted);

            cons.SearchAsync(String.Empty, FilterKind.None, "Contacts Test #1");
        }
        void Contacts_SearchCompleted(object sender, ContactsSearchEventArgs e)
        {
           // MessageBox.Show(e.Results.Count().ToString());
            try
            {
List<CustomContact> listOfContacts = new List<CustomContact>();
foreach (var c in e.Results)
{
    CustomContact contact  = new CustomContact();
    contact.DisplayName = c.DisplayName;
    var number = c.PhoneNumbers.FirstOrDefault(); //change this to whatever number you want
    if (number != null)
        contact.Number = number.PhoneNumber;
    else
        contact.Number = "";
            }
            catch (System.Exception)
            {
                //No results
            }

            if (ContactResultsData.Items.Any())
            {
                ContactResultsLabel.Text = "results";
            }
            else
            {
                ContactResultsLabel.Text = "no results";
            }
    listOfContacts.Add(contact);
}
ContactResultsData.DataContext = listOfContacts;

xaml page

<Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
    <StackPanel>
        <TextBlock Name="ContactResultsLabel" Text="results are loading..." Style="{StaticResource PhoneTextLargeStyle}" TextWrapping="Wrap" />

        <ListBox Name="ContactResultsData" ItemsSource="{Binding}" Height="200" Margin="24,0,0,0" >
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <TextBlock Name="ContactResults" Text="{Binding Path=DisplayName, Mode=OneWay}" />
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
    </StackPanel>
    <Button x:Name="ButtonContacts"
            Content="Get All Contacts"
            FontSize="15"
            Width="200"
            Height="70"
            Background="AliceBlue"
            Foreground="Blue"
            HorizontalAlignment="Left"
            Click="ButtonContacts_Click"></Button>
</Grid>

But when I put listOfContacts in listbox ContactResultsData it not shows contacts in the list box and when I put breakpoint at this line ContactResultsData.DataContext = listOfContacts the contacts are already exists in the listOfContacts then why it not shows in the listbox ContactResultsData . Kindly suggest me, waiting for your reply. Thanks

Answer 1

My suggestion is to expose listOfContacts to public property. Also change its type to ObservableCollection . Change XAML like this:

<Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
    <StackPanel>
        <TextBlock Name="ContactResultsLabel" Text="results are loading..." Style="{StaticResource PhoneTextLargeStyle}" TextWrapping="Wrap" />

        <ListBox Name="ContactResultsData" ItemsSource="{Binding ContactList}" Height="200" Margin="24,0,0,0" >
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <TextBlock Name="ContactResults" Text="{Binding Path=DisplayName, Mode=OneWay}" />
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
    </StackPanel>
    <Button x:Name="ButtonContacts"
            Content="Get All Contacts"
            FontSize="15"
            Width="200"
            Height="70"
            Background="AliceBlue"
            Foreground="Blue"
            HorizontalAlignment="Left"
            Click="ButtonContacts_Click"></Button>
</Grid>

In your code-behind you should operate on contacts public property only by removing and adding items - NOT changing reference to it, because that'll break binding between XAML and code.