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POListbox data binding with Viewmodel not showing up windows phone
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  1. POListbox data binding with Viewmodel not showing up windows phone
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    copied!<p>I am working on a windows phone application that uses a local database and MVVM. My listbox is not showing the WeatherList that it is binded to. I am adding a single WeatherItem to the local database in the App.xaml.cs file and it's being added successfully, but it is not showing up in the listbox when running the app. I would really appreciate any help. I have the following setup:</p> <p>MainPage.xaml:</p> <pre><code>&lt;phone:PhoneApplicationPage.Resources&gt; &lt;DataTemplate x:Key="ForecastListItemTemplate"&gt; &lt;StackPanel Orientation="Horizontal" Margin="0, 400, 0, 0" Width="480" Height="100"&gt; &lt;StackPanel Width="190" VerticalAlignment="Center"&gt; &lt;TextBlock HorizontalAlignment="Center" Text="{Binding Path=DayOfWeek}" FontFamily="Segoe WP" FontWeight="ExtraBold" FontSize="36" Foreground="#545d61"&gt;&lt;/TextBlock&gt; &lt;TextBlock HorizontalAlignment="Center" Text="{Binding Path=ItemDay}" FontFamily="Segoe WP Light" FontSize="36" Foreground="#545d61"&gt;&lt;/TextBlock&gt; &lt;/StackPanel&gt; &lt;Image Height="100" Width="100" Source="{Binding Path=ImageSource}"&gt;&lt;/Image&gt; &lt;StackPanel Width="190" VerticalAlignment="Center"&gt; &lt;StackPanel HorizontalAlignment="Center" Orientation="Horizontal"&gt; &lt;TextBlock Text="↑" FontFamily="Segoe WP" FontWeight="ExtraBold" FontSize="36" Foreground="#545d61"&gt;&lt;/TextBlock&gt; &lt;TextBlock HorizontalAlignment="Center" Margin="4, 0, 4, 0" Text="{Binding Path=High}" FontFamily="Segoe WP" FontWeight="ExtraBold" FontSize="36" Foreground="#0da5d0"&gt;&lt;/TextBlock&gt; &lt;TextBlock Text="↓" FontFamily="Segoe WP" FontWeight="ExtraBold" FontSize="36" Foreground="#545d61"&gt;&lt;/TextBlock&gt; &lt;TextBlock HorizontalAlignment="Center" Margin="4, 0, 4, 0" Text="{Binding Path=Low}" FontFamily="Segoe WP" FontWeight="ExtraBold" FontSize="36" Foreground="#0da5d0"&gt;&lt;/TextBlock&gt; &lt;/StackPanel&gt; &lt;TextBlock HorizontalAlignment="Center" Text="{Binding Path=Condition}" FontFamily="Segoe WP Light" FontSize="24" Foreground="#545d61"&gt;&lt;/TextBlock&gt; &lt;/StackPanel&gt; &lt;/StackPanel&gt; &lt;/DataTemplate&gt; &lt;/phone:PhoneApplicationPage.Resources&gt; &lt;!--LayoutRoot is the root grid where all page content is placed--&gt; &lt;Grid x:Name="LayoutRoot" Background="#e1e4e4"&gt; &lt;Grid.RowDefinitions&gt; &lt;RowDefinition Height="Auto"/&gt; &lt;RowDefinition Height="*"/&gt; &lt;/Grid.RowDefinitions&gt; &lt;ListBox x:Name="WeatherListBox" ItemsSource="{Binding WeatherList}" Margin="0, 400, 0, 96" Width="480" ItemTemplate="{StaticResource ForecastListItemTemplate}"&gt; &lt;/ListBox&gt; &lt;/Grid&gt; </code></pre> <p>WeatherViewModel.cs</p> <pre><code>public class WeatherViewModel : INotifyPropertyChanged { // LINQ to SQL data context for the local database. private ToDoDataContext weatherDB; // Class constructor, create the data context object. public WeatherViewModel() { weatherDB = new ToDoDataContext(); } // All to-do items. private ObservableCollection&lt;WeatherItem&gt; _weatherList; public ObservableCollection&lt;WeatherItem&gt; WeatherList { get { return _weatherList; } set { _weatherList = value; NotifyPropertyChanged("WeatherList"); } } // Write changes in the data context to the database. public void SaveChangesToDB() { weatherDB.SubmitChanges(); } // Query database and load the collections and list used by the pivot pages. public void LoadCollectionsFromDatabase() { // Specify the query for all to-do items in the database. var weatherItemsInDB = from WeatherItem weather in weatherDB.Forecasts select weather; // Query the database and load all to-do items. WeatherList = new ObservableCollection&lt;WeatherItem&gt;(weatherItemsInDB); } // Add a to-do item to the database and collections. public void AddWeatherItem(WeatherItem newWeatherItem) { // Add a to-do item to the data context. weatherDB.Forecasts.InsertOnSubmit(newWeatherItem); // Save changes to the database. weatherDB.SubmitChanges(); // Add a to-do item to the "all" observable collection. WeatherList.Add(newWeatherItem); } #region INotifyPropertyChanged Members public event PropertyChangedEventHandler PropertyChanged; // Used to notify Silverlight that a property has changed. private void NotifyPropertyChanged(string propertyName) { if (PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } } #endregion } </code></pre> <p>ToDoDataContext.cs</p> <pre><code>public class ToDoDataContext : DataContext { // Pass the connection string to the base class. public ToDoDataContext() : base("Data Source=isostore:/AppDB.sdf") { } public ToDoCategory activeCategory; // Specify a table for the to-do items. public Table&lt;ToDoItem&gt; Items; // Specify a table for the categories. public Table&lt;ToDoCategory&gt; Categories; //Weather stuff public WeatherItem currentWeather; // Specify a table for the to-do items. public Table&lt;WeatherItem&gt; Forecasts; } [Table] public class WeatherItem : INotifyPropertyChanged, INotifyPropertyChanging { // Define ID: private field, public property, and database column. private int _weatherItemId; [Column(IsPrimaryKey = true, IsDbGenerated = true, DbType = "INT NOT NULL Identity", CanBeNull = false, AutoSync = AutoSync.OnInsert)] public int WeatherItemId { get { return _weatherItemId; } set { if (_weatherItemId != value) { NotifyPropertyChanging("WeatherItemId"); _weatherItemId = value; NotifyPropertyChanged("WeatherItemId"); } } } // Define item name: private field, public property, and database column. private string _itemDay; [Column] public string ItemDay { get { return _itemDay; } set { if (_itemDay != value) { NotifyPropertyChanging("ItemDay"); _itemDay = value; NotifyPropertyChanged("ItemDay"); } } } private string _dayOfWeek; [Column] public string DayOfWeek { get { return _dayOfWeek; } set { if (_dayOfWeek != value) { NotifyPropertyChanging("DayOfWeek"); _dayOfWeek = value; NotifyPropertyChanged("DayOfWeek"); } } } // Define completion value: private field, public property, and database column. private string _high; [Column] public string High { get { return _high; } set { if (_high != value) { NotifyPropertyChanging("High"); _high = value; NotifyPropertyChanged("High"); } } } private string _low; [Column] public string Low { get { return _low; } set { if (_low != value) { NotifyPropertyChanging("Low"); _low = value; NotifyPropertyChanged("Low"); } } } private string _condition; [Column] public string Condition { get { return _condition; } set { if (_condition != value) { NotifyPropertyChanging("Condition"); _condition = value; NotifyPropertyChanged("Condition"); } } } private string _imageSource; [Column] public string ImageSource { get { return _imageSource; } set { if (_imageSource != value) { NotifyPropertyChanging("ImageSource"); _imageSource = value; NotifyPropertyChanged("ImageSource"); } } } // Version column aids update performance. [Column(IsVersion = true)] private Binary _version; #region INotifyPropertyChanged Members public event PropertyChangedEventHandler PropertyChanged; // Used to notify that a property changed private void NotifyPropertyChanged(string propertyName) { if (PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } } #endregion #region INotifyPropertyChanging Members public event PropertyChangingEventHandler PropertyChanging; // Used to notify that a property is about to change private void NotifyPropertyChanging(string propertyName) { if (PropertyChanging != null) { PropertyChanging(this, new PropertyChangingEventArgs(propertyName)); } } #endregion } </code></pre> <p>Mainpage.xaml.cs</p> <pre><code>// Constructor public MainPage() { InitializeComponent(); this.DataContext = App.WeatherViewModel; } </code></pre> <p>App.xaml.cs</p> <pre><code>public partial class App : Application { private static ToDoViewModel viewModel; public static ToDoViewModel ViewModel { get { return viewModel; } } private static WeatherViewModel weatherViewModel; public static WeatherViewModel WeatherViewModel { get { return weatherViewModel; } } /// &lt;summary&gt; /// Provides easy access to the root frame of the Phone Application. /// &lt;/summary&gt; /// &lt;returns&gt;The root frame of the Phone Application.&lt;/returns&gt; public PhoneApplicationFrame RootFrame { get; private set; } /// &lt;summary&gt; /// Constructor for the Application object. /// &lt;/summary&gt; public App() { // Global handler for uncaught exceptions. UnhandledException += Application_UnhandledException; // Standard Silverlight initialization InitializeComponent(); // Phone-specific initialization InitializePhoneApplication(); // Show graphics profiling information while debugging. if (System.Diagnostics.Debugger.IsAttached) { // Display the current frame rate counters. Application.Current.Host.Settings.EnableFrameRateCounter = true; // Show the areas of the app that are being redrawn in each frame. //Application.Current.Host.Settings.EnableRedrawRegions = true; // Enable non-production analysis visualization mode, // which shows areas of a page that are handed off to GPU with a colored overlay. //Application.Current.Host.Settings.EnableCacheVisualization = true; // Disable the application idle detection by setting the UserIdleDetectionMode property of the // application's PhoneApplicationService object to Disabled. // Caution:- Use this under debug mode only. Application that disables user idle detection will continue to run // and consume battery power when the user is not using the phone. PhoneApplicationService.Current.UserIdleDetectionMode = IdleDetectionMode.Disabled; } // Create the database if it does not exist. using (ToDoDataContext db = new ToDoDataContext()) { if (db.DatabaseExists() == false) { // Create the local database. db.CreateDatabase(); // Prepopulate the categories. db.Categories.InsertOnSubmit(new ToDoCategory { Name = "Home" }); db.Categories.InsertOnSubmit(new ToDoCategory { Name = "Work" }); db.Categories.InsertOnSubmit(new ToDoCategory { Name = "School" }); db.Forecasts.InsertOnSubmit(new WeatherItem { DayOfWeek = "Mon", ItemDay = "Sept 4", Condition = "Mostly Sunny", High = "105", Low = "88", ImageSource = "images/Weather/45.png" }); // Save categories to the database. db.SubmitChanges(); } } // Create the ViewModel object. viewModel = new ToDoViewModel(); weatherViewModel = new WeatherViewModel(); // Query the local database and load observable collections. viewModel.LoadCollectionsFromDatabase(); weatherViewModel.LoadCollectionsFromDatabase(); } </code></pre> <p>Thanks!</p>
 

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