Azure Mobile Services, Part 1: Listing 3

MainPage.xaml.cs

using System.Collections.Generic;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Navigation;
using System.Threading.Tasks;

// The Blank Page item template is documented at http://go.microsoft.com/fwlink/?LinkId=234238

namespace VSMMobileServiceClient
{
    /// <summary>
    /// An empty page that can be used on its own or navigated to within a Frame.
    /// </summary>
    public sealed partial class MainPage : Page
    {
        List<ContactItem> _contacts;
        ContactItem _item;
        bool _update = false;

        public MainPage()
        {
            this.InitializeComponent();
            ClearItem();
        }

        private async void ClearItem()
        {
            _item = new ContactItem();
            Contact.DataContext = _item;
            Delete.IsEnabled = false;
            _update = false;
            await UpdateStatus(string.Empty);
        }

        private async Task UpdateStatus(string status)
        {
            Status.Text = status;
            await Task.Delay(250);
        }

        /// <summary>
        /// Invoked when this page is about to be displayed in a Frame.
        /// </summary>
        /// <param name="e">Event data that describes how this page was reached.  The Parameter
        /// property is typically used to configure the page.</param>
        protected async override void OnNavigatedTo(NavigationEventArgs e)
        {
            await GetContacts();
        }

        private async Task GetContacts()
        {
            _contacts = await App.MobileService.GetTable<ContactItem>().ToListAsync();
            Contacts.ItemsSource = _contacts;
        }

        private async void Save_Click(object sender, RoutedEventArgs e)
        {
            if (_update)
                await App.MobileService.GetTable<ContactItem>().UpdateAsync(_item);
            else
                await App.MobileService.GetTable<ContactItem>().InsertAsync(_item);

            await UpdateStatus("Saved");
            await GetContacts();
            ClearItem();
        }

        private void Contacts_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            var selectedItem = (sender as ListBox).SelectedItem as ContactItem;
            if (selectedItem != null)
            {
                _item = selectedItem;
                Contact.DataContext = _item;
                _update = true;
                Delete.IsEnabled = true;
            }
        }

        private async void Delete_Click(object sender, RoutedEventArgs e)
        {
            await App.MobileService.GetTable<ContactItem>().DeleteAsync(_item);
            await UpdateStatus("Deleted");
            ClearItem();
            await GetContacts();
        }
    }
}

About the Author

Eric Vogel is a Senior Software Developer for Red Cedar Solutions Group in Okemos, Michigan. He is the president of the Greater Lansing User Group for .NET. Eric enjoys learning about software architecture and craftsmanship, and is always looking for ways to create more robust and testable applications. Contact him at vogelvision@gmail.com.