Exception when databinding result from contact query in wp8 c#

Question

I have been attempting to embed a contact picker within my windows phone 8 app. The idea is simple...show contacts, allow the user to tap the contacts they wish to save for use by my app, save selected items. Implementing this has not been as simple as i thought though.

I have the following code, mainly from MSDN samples:

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 Microsoft.Phone.UserData;
using System.Diagnostics;

namespace appNamespace
{
    public partial class contact : PhoneApplicationPage
    {
        public contact()
        {
            InitializeComponent();
        }

        private void showContacts(object sender, RoutedEventArgs e)
        {
            Contacts cons = new Contacts();

            //Identify the method that runs after the asynchronous search completes.
            cons.SearchCompleted += new EventHandler<ContactsSearchEventArgs>(Contacts_SearchCompleted);

            //Start the asynchronous search.
            cons.SearchAsync(String.Empty, FilterKind.None, "Contacts Test #1");
        }

        void Contacts_SearchCompleted(object sender, ContactsSearchEventArgs e)
        {
            //Do something with the results.
            MessageBox.Show(e.Results.Count().ToString());
            try
            {
                //Bind the results to the user interface.
                ContactResultsData.DataContext = e.Results;
            }
            catch (System.Exception)
            {
                //No results
            }

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

        public void saveContacts(object sender, RoutedEventArgs e)
        {
            String strItem;
            foreach (Object selecteditem in ContactResultsData.SelectedItems)
            {
                MessageBox.Show(selecteditem.ToString());
                strItem = selecteditem as String;
                ContactResultsLabel.Text = strItem;
                System.Diagnostics.Debug.WriteLine(strItem);
                MessageBox.Show("Saving " + strItem);
            }
        }

    }
}

When running the code on a device, Lumia 920, the app shows the count of how many contacts, but does not show the databound list. (See XAML below) Instead, the app halts and an exception is thrown (ApplicationException, no details offered b debugger)

<phone:PhoneApplicationPage
    x:Class="appNamespace.contact"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
    xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    FontFamily="{StaticResource PhoneFontFamilyNormal}"
    FontSize="{StaticResource PhoneFontSizeNormal}"
    Foreground="{StaticResource PhoneForegroundBrush}"
    SupportedOrientations="Portrait" Orientation="Portrait"
    mc:Ignorable="d"
    shell:SystemTray.IsVisible="True">

    <!--LayoutRoot is the root grid where all page content is placed-->
    <Grid x:Name="LayoutRoot" Background="Transparent">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>

        <!--TitlePanel contains the name of the application and page title-->
        <StackPanel Grid.Row="0" Margin="12,17,0,28">
            <TextBlock Text="appName" Style="{StaticResource PhoneTextNormalStyle}"/>
            <TextBlock Text="contacts" Margin="9,-7,0,0" Style="{StaticResource PhoneTextTitle1Style}"/>
        </StackPanel>

        <!--ContentPanel - place additional content here-->
        <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
            <StackPanel Height="Auto" Width="Auto" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Margin="0,0,0,10" >

                <TextBlock Name="ContactResultsLabel" Text="results are loading..." Style="{StaticResource PhoneTextLargeStyle}" TextWrapping="Wrap" />

                <ListBox Name="ContactResultsData" ItemsSource="{Binding}" Height="436" Margin="12,0" SelectionMode="Multiple" >
                    <ListBox.ItemTemplate>
                        <DataTemplate>
                            <TextBlock Name="ContactResults" Style="{StaticResource PhoneFontSizeMedium}" Text="{Binding Path=DisplayName, Mode=OneWay}" />
                        </DataTemplate>
                    </ListBox.ItemTemplate>
                </ListBox>
            </StackPanel>
            <Button x:Name="showButton" Content="Show Contacts" HorizontalAlignment="Left" VerticalAlignment="Top" Width="218" Height="90" Margin="0,531,0,0" Click="showContacts"/>
            <Button x:Name="saveButton" Content="Save Contacts" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="238,531,0,0" Width="218" Height="90"/>
        </Grid>
    </Grid>
</phone:PhoneApplicationPage>

Really hope someone can help, I cannot figure out why this exception arises. Thank you.

Answer 1

<TextBlock Name="ContactResults" Style="{StaticResource PhoneFontSizeMedium}" Text="{Binding Path=DisplayName, Mode=OneWay}" />

PhoneFontSizeMedium is, as the name indicates, a size. You can't apply it directly to a TextBlock.

What you're trying to do is:

<TextBlock Name="ContactResults" FontSize="{StaticResource PhoneFontSizeMedium}" Text="{Binding Path=DisplayName, Mode=OneWay}" />