儘管在Windows Phone 8應用程序中使用了Fody PropertyChanged包，但數據綁定視圖元素仍未更新？

Question

我有一個C＃Windows Phone 8 MVVM應用程序與Fody PropertyChanged軟件包安裝。我已經添加了ImplementPropertyChanged指令中的類聲明之前：

[CompilerGenerated] 
[GeneratedCode("Radarc", "4.0")] 
[ImplementPropertyChanged] 
public partial class MilitaryRobots_VideosViewModel : ViewModelsBase.VMBase, IViewModels.IMilitaryRobots_VideosViewModel, INotifyPropertyChanged 

我在班上以下兩個屬性，我結合景觀元素：

private Visibility _showDetailsVideo = Visibility.Collapsed; 

    public Visibility ShowDetailsVideo 
    { 
     get 
     { 
      return this._showDetailsVideo; 
     } 

     set 
     { 
      this._showDetailsVideo = value; 
      this.ShowMainScreen = value == Visibility.Visible ? Visibility.Collapsed : Visibility.Visible; 
     } 
    } 

    private Visibility _showMainScreen = Visibility.Visible; 

    /// <summary> 
    /// Never set this property, instead set ShowDetailsVideo instead. 
    /// </summary> 
    public Visibility ShowMainScreen 
    { 
     get 
     { 
      return this._showMainScreen; 
     } 

     private set 
     { 
      this._showMainScreen = value; 
     } 
    } 

一個查看元素的Visibility屬性必然與View Model的ShowDetailsVideo屬性有關。另一個查看元素的可見性屬性綁定到查看模型的ShowMainScreen屬性。在運行時，訪問屬性獲取者，指示綁定的View元素對正在訪問屬性至少一次。此外，這兩個視圖元素確實具有適當的可見性狀態。但是，如果我改變ShowDetailsVideo酒店在運行時，制定者被訪問，但不的干將，表明性質和視圖元素屬性之間的佈線不工作，儘管我使用Fody PropetyChanged的包。財產訪問行爲與Fody包甚至不在那裏相同。

我該如何解決這個問題並使其工作，以便在運行時正確更新Visibility屬性的視圖元素對？我認爲Fody PropertyChanged軟件包應該使實施屬性更改通知變得不必要。

Answer 1

我在添加這個答案，因爲這個問題花了幾個小時才能找到並修復。我正在將答案標記爲社區wiki，因爲我沒有爲此尋求功勞，只是爲了拯救別人我診斷它的麻煩。

以下是更正後的視圖模型代碼，以使屬性更改通知正常工作。視圖模型中的可綁定屬性發生更改時，View並未更新，因爲我沒有在屬性設置器中調用基本的SetProperty（）方法，而是僅執行直接分配，因此未觸發屬性更改通知。你可以在我原來的帖子中的屬性設置器中看到這個。只需添加SetProperty（）調用即可解決所有問題。

所以，如果您的視圖模型類從像BindableBase（見下文）一類下降，你不需要Fody的PropertyChanged插件可言，但要確保你在你的屬性設置器調用的SetProperty（）而不是做直接分配給支持該屬性的數據成員。

更新屬性setter/getter方法

private Visibility _showDetailsVideo = Visibility.Collapsed; 

    public Visibility ShowDetailsVideo 
    { 
     get 
     { 
      return this._showDetailsVideo; 
     } 

     set 
     { 
      SetProperty(ref this._showDetailsVideo, value); 
      this.ShowMainScreen = value == Visibility.Visible ? Visibility.Collapsed : Visibility.Visible; 
     } 
    } 

    private Visibility _showMainScreen = Visibility.Visible; 

    /// <summary> 
    /// Never set this property, instead set ShowDetailsVideo instead. 
    /// </summary> 
    public Visibility ShowMainScreen 
    { 
     get 
     { 
      return this._showMainScreen; 
     } 

     private set 
     { 
      SetProperty(ref this._showMainScreen, value); 
     } 
    } 

我的視圖模型從

/// <summary> 
/// Abstraction of data-binder that notifies properties changes to the suitable View. 
/// </summary> 
public abstract class BindableBase : INotifyPropertyChanged 
{ 
    /// <summary> 
    /// Event launched when a property of the bindable object has changed. 
    /// </summary> 
    public event PropertyChangedEventHandler PropertyChanged; 

    /// <summary> 
    /// Sets the value of the binded property. 
    /// </summary> 
    /// <typeparam name="T">The generic type.</typeparam> 
    /// <param name="storage">The type of the property.</param> 
    /// <param name="value">The value of the property.</param> 
    /// <param name="propertyName">The name of the property.</param> 
    /// <returns>A boolean indicating the success of the assignation.</returns> 
    protected bool SetProperty<T>(ref T storage, T value, [CallerMemberName]String propertyName = null) 
    { 
     if (Equals(storage, value)) return false; 

     storage = value; 
     OnPropertyChanged(propertyName); 
     return true; 
    } 

    /// <summary> 
    /// Event handler for the PropertyChanged event. 
    /// </summary> 
    /// <param name="propertyName">The name of the property that has changed.</param> 
    protected void OnPropertyChanged(string propertyName = null) 
    { 
     //if (Debugger.IsAttached) 
     // Debug.WriteLine("Property changed: " + propertyName); 

     var eventHandler = PropertyChanged; 
     if (eventHandler != null) 
      eventHandler(this, new PropertyChangedEventArgs(propertyName)); 
    } 

    /// <summary> 
    /// Initializes the bindable object. 
    /// </summary> 
    /// <param name="parameters">Dictionary with the parameters.</param> 
    public virtual void Initialize(IDictionary<string, string> parameters) 
    { 

    } 
}