如何使用INotifyPropertyChanged更新派生屬性

Question

我有一個綁定列表中的XTratreeList（DevExress）其中一個子節點需要顯示parentnode'e屬性的幾個屬性。我有以下代碼。

public abstract class ClassBase : INotifyPropertyChanged 
{ 
    protected static int initialId = 0; 

    private int id; 
    private int parentID; 
    private string productName; 
    private string productType; 
    private string colorProductType; 

    private void RaisePropertyChanged(string propertyName) 
    { 
     if (PropertyChanged != null) 
      PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); 
    } 

    public int ID 
    { 
     get { return id; } 
     set 
     { 
      if (id == value) 
       return; 

      id = value; 
      RaisePropertyChanged("ID"); 
     } 
    } 

    public int ParentID 
    { 
     get { return parentID; } 
     set 
     { 
      if (parentID == value) 
       return; 

      parentID = value; 
      RaisePropertyChanged("ParentID"); 
     } 
    } 

    public string ProductName 
    { 
     get { return productName; } 
     set 
     { 
      if (productName == value) 
       return; 

      productName = value; 
      RaisePropertyChanged("ProductName"); 
     } 
    } 

    public string ProductType 
    { 
     get { return productType; } 
     set 
     { 
      if (productType == value) 
       return; 

      productType = value; 
      RaisePropertyChanged("ProductType"); 
      RaisePropertyChanged("ColorProductType"); 
     } 
    } 

    public string ColorProductType 
    { 
     get { return colorProductType ; } 
     set 
     { 
      if (colorProductType == value) 
       return; 

      colorProductType = value; 
      RaisePropertyChanged("ColorProductType"); 
     } 
    } 

    #region INotifyPropertyChanged Members 

    public event PropertyChangedEventHandler PropertyChanged; 

    #endregion 
}` 

我的要求是有ColorProductType屬性更改時ProductType屬性發生變化，基本上ProductType是父節點屬性和ColorProductType - 孩子的。所以在改變父母的財產時，孩子需要改變。我將這兩個屬性綁定到2個文本框。所以改變父道具應該改變兩個文本框，但反之亦然。 RaisePropertyChanged("ColorProductType");父母內部沒有工作，colorproducttype爲空，這裏有什麼問題？

Answer 1

RaisePropertyChanged實際上並未更新該屬性。它只是表示PropertyChanged事件。某處某處必須訂閱它並相應地更新其他屬性。就像這樣：

public abstract class ClassBase : INotifyPropertyChanged 
{ 
    private string productType; 
    private string colorProductType; 

    public ClassBase() 
    { 
     this.PropertyChanged += HandlePropertyChanged; 
    } 

    private void HandlePropertyChanged(object sender, PropertyChangedEventArgs e) 
    { 
     if(e.PropertyName == "ProductType") 
     { 
      // update ColorProductType here 
     } 
    } 

    private void RaisePropertyChanged(string propertyName) 
    { 
     if (PropertyChanged != null) 
      PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); 
    } 

    public string ProductType 
    { 
     get { return productType; } 
     set 
     { 
      if (productType == value) 
       return; 

      productType = value; 
      RaisePropertyChanged("ProductType"); 
     } 
    } 

    public string ColorProductType 
    { 
     get { return colorProductType ; } 
     set 
     { 
      if (colorProductType == value) 
       return; 

      colorProductType = value; 
      RaisePropertyChanged("ColorProductType"); 
     } 
    } 

    #region INotifyPropertyChanged Members 

    public event PropertyChangedEventHandler PropertyChanged; 

    #endregion 
} 

當然，這是完全矯枉過正。當ProductType更新，您可以更新ColorProductType，讓PropertyChanged事件和數據綁定處理文本框更新：

public string ProductType 
{ 
    get { return productType; } 
    set 
    { 
     if (productType == value) 
      return; 

     productType = value; 

     // update ColorProductType here 

     RaisePropertyChanged("ProductType"); 
    } 
}