値を設定し、viewmodelでRaisePropertyChangedを呼び出した後、Prism Xamarinフォームビューが更新されませんか？

Question

ViewmodelからViewに値をバインドできませんでした。値が設定されていることがわかり（ProductList）、デバッグ中にRaisePropertyChangedを呼び出すことができます。私はApp.csの最初のページ（NavigationService.NavigateAsync（ "StudentPage/NavigationPage/StudentRedeemPage"）;）に設定している間、それは動作しますが、呼び出された/別のページからStudentRedeemPageにナビゲートされたときには機能しません。

XAML

<?xml version="1.0" encoding="utf-8" ?> 
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" 
      xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
      xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms" 
      prism:ViewModelLocator.AutowireViewModel="True" 
      x:Class="mySeeds.Views.StudentRedeemPage" 
      Title="Redeem"> 
    <ContentPage.Content> 
     <Grid x:Name="MainGrid"> 
      <Grid.RowDefinitions> 
       <RowDefinition Height="2*" /> 
       <RowDefinition Height="3*" /> 
      </Grid.RowDefinitions> 
      <Grid Grid.Row="0" 
        Grid.RowSpan="1" 
        HorizontalOptions="FillAndExpand" 
        VerticalOptions="FillAndExpand" 
        BackgroundColor="{StaticResource RedeemBanner}"> 
       <Grid.RowDefinitions> 
        <RowDefinition Height="3*"/> 
        <RowDefinition Height="1*"/> 
       </Grid.RowDefinitions> 
       <Grid.ColumnDefinitions> 
        <ColumnDefinition Width="6*" /> 
        <ColumnDefinition Width="4*" /> 
       </Grid.ColumnDefinitions> 

       <Image Source="Icon" 
         VerticalOptions="Center" 
         HorizontalOptions="Center" 
         Grid.Column="1" 
         Grid.Row="0"/> 
       <StackLayout Grid.Column="0" 
          Grid.Row="0" 
          HorizontalOptions="CenterAndExpand" 
          VerticalOptions="Center"> 
        <Label Text="REWARD SHOP" 
          TextColor="White" 
          FontSize="Medium" 
          FontAttributes="Bold" 
          VerticalTextAlignment="Center" 
          LineBreakMode="TailTruncation"/> 
        <Label Text="{Binding User_Profile_Table.Points_Earned, StringFormat='{0} Seeds'}" 
          TextColor="White" 
          FontSize="Large" 
          FontAttributes="Bold" 
          VerticalTextAlignment="Center" 
          LineBreakMode="WordWrap"/> 
       </StackLayout> 
       <StackLayout Grid.Row="1" Grid.ColumnSpan="2" > 
        <Label Text="Partners" BackgroundColor="{StaticResource RedeemTab}" HorizontalOptions="FillAndExpand" VerticalOptions="Center" /> 
        <ListView 
          Margin="0,0,0,0" 
          HorizontalOptions="FillAndExpand" 
          VerticalOptions="FillAndExpand" 
          ItemsSource="{Binding ProductList}" 
          HasUnevenRows="true" 
          CachingStrategy="RecycleElement"> 
         <ListView.ItemTemplate> 
          <DataTemplate> 
           <ViewCell> 
            <Grid Padding="0, 0, 10, 0"> 
             <Grid.RowDefinitions> 
              <RowDefinition Height="Auto"/> 
             </Grid.RowDefinitions> 
             <Grid.ColumnDefinitions> 
              <ColumnDefinition Width="30"/> 
              <ColumnDefinition Width="*"/> 
              <ColumnDefinition Width="Auto"/> 
             </Grid.ColumnDefinitions> 
             <Image x:Name="Img" 
             Grid.Row="0" Grid.Column="0" 
             HorizontalOptions="Center" 
             VerticalOptions="Center" 
             HeightRequest="30" 
             WidthRequest="30" 
             Source="{Binding ImageUrl}"/> 
             <StackLayout Grid.Row="0" Grid.Column="1" VerticalOptions="Center"> 
              <Label Text="{Binding SalesPriceIncVat,StringFormat='{0} Seeds'}" 
             TextColor="{StaticResource RedeemStatusBar}" 
             FontAttributes="Bold" 
             VerticalOptions="Center"/> 
              <Label Text="{Binding Name}" 
             VerticalOptions="Center"/> 
             </StackLayout> 
             <Button x:Name="btnRedeem" 
             Text="GET IT!" 
             TextColor="White" 
             BackgroundColor="{StaticResource RedeemLightGreen}" 
             Grid.Row="0" Grid.Column="2"> 

             </Button> 
            </Grid> 
           </ViewCell> 
          </DataTemplate> 
         </ListView.ItemTemplate> 
        </ListView> 

       </StackLayout> 
      </Grid> 
     </Grid> 
    </ContentPage.Content> 
</ContentPage> 

のViewModel

public class StudentRedeemPageViewModel : NavigationViewModelBase 
{ 
    private List<Data> _productList; 
    public List<Data> ProductList 
    { 
     get { return _productList; } 
     set 
     { 
      SetProperty(ref _productList, value); 
      RaisePropertyChanged(nameof(ProductList)); 
     } 
    } 

    private User_Profile_Table user_Profile_Table; 
    public User_Profile_Table User_Profile_Table 
    { 
     get { return user_Profile_Table; } 
     set 
     { 
      SetProperty(ref user_Profile_Table, value); 
      RaisePropertyChanged(nameof(User_Profile_Table)); 
     } 
    } 

    private ProductModel _product_Table; 
    public ProductModel Product_Table 
    { 
     get { return _product_Table; } 
     set 
     { 
      SetProperty(ref _product_Table, value); 
      RaisePropertyChanged(nameof(Product_Table)); 
     } 
    } 

    public DelegateCommand GetProductListCommand { get; private set; } 
    public DelegateCommand UserProfileCommand { get; private set; } 

    public DelegateCommand NavigateToRedeemPage { get; set; } 

    private IRequestProvider _requestProvider; 

    public StudentRedeemPageViewModel(IDeviceService deviceService, INavigationService navigationService, 
     IPageDialogService pageDialogService, IRequestProvider requestProvider) 
     : base(deviceService, navigationService, pageDialogService) 
    { 

     _requestProvider = requestProvider; 

     NavigateToRedeemPage = new DelegateCommand(() => NavigateCommand.Execute("VocherPage")); 

     GetProductListCommand = new DelegateCommand(async() => await GetProductList()); 
     UserProfileCommand = new DelegateCommand(async() => await GetUserProfile()); 


     UserProfileCommand.Execute(); 
     GetProductListCommand.Execute(); 
    } 
    async Task GetProductList() 
    { 
     List<Data> Test = new List<Data>(); 
     string username = "admin@xxxx.com"; 
     string password = "xxxxxxxxx"; 
     string svcCredentials = Convert.ToBase64String(System.Text.Encoding.UTF8.GetBytes(username + ":" + password)); 

     if (svcCredentials != null) 
     { 
      var client = new HttpClient(); 
      client.BaseAddress = new Uri("https://xxxxxx.com/"); 
      client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", svcCredentials); 
      var productsResponse = await client.GetAsync("xxxxxx/api/xxxx/"); 
      var productsJson = productsResponse.Content.ReadAsStringAsync().Result; 
      ProductModel members = JsonConvert.DeserializeObject<ProductModel>(productsJson); 
      ProductList = members.Data; 
     } 
    } 

    async Task GetUserProfile() 
    { 
     User_Profile_Table = await _requestProvider.GetAsync<User_Profile_Table>(
      GlobalSetting.Instance.UserProfileTableEndpoint, Settings.AuthAccessToken); 
    } 
} 

モデル

public class ProductModel 
{ 
    public List<Data> Data { get; set; } 
    public string FirstItem { get; set; } 
    public string HasNextPage { get; set; } 
    public string HasPreviousPage { get; set; } 
    public string LastItem { get; set; } 
    public string PageNumber { get; set; } 
    public string PageSize { get; set; } 
    public string TotalItems { get; set; } 
    public string TotalPages { get; set; } 
} 

public class Data 
{ 
    [JsonProperty("Data")] 
    public string ProductId { get; set; } 
    public string PartnerId { get; set; } 
    public string Name { get; set; } 
    public string Description { get; set; } 
    public string SalesPriceIncVat { get; set; } 
    public string SalesPriceExcVat { get; set; } 
    public string SalesVat { get; set; } 
    public string ValidFromDateUtc { get; set; } 
    public string ValidToDateUtc { get; set; } 
    public string TermsAndConditions { get; set; } 
    public string UsageInstructions { get; set; } 
    public string SlaTime { get; set; } 
    public string SlaText { get; set; } 
    public string Units { get; set; } 
    public string StockRequired { get; set; } 
    public string UseVariableValues { get; set; } 
    public string MinVariableValue { get; set; } 
    public string MaxVariableValue { get; set; } 
    public string VariableValueAllowedIncrements { get; set; } 
    public string ImageUrl { get; set; } 
    public string ImageCaption { get; set; } 
    public string CurrentStockBalance { get; set; } 
} 

Answer 1

はどのようにあなたのビューにのviewmodelを結合した、上記の一切のBindingContextはありません。