WPF MVVM Combox在驗證失敗時未保留舊值

Question

我有一個綁定到使用MVVM的屬性的combox控件。有一個在價值變動set方法進行驗證。該問題的價值得到改變，以新的價值，即使驗證失敗，而不是保留舊的價值..

下面是XAML：

<ComboBox Grid.Column="1" Grid.Row="1" Width="200" ItemsSource="{Binding Path=Applications, Mode=OneTime}" SelectedItem="{Binding RelativeSource={RelativeSource AncestorType={x:Type UserControl}}, Path=DataContext.Application, Mode=TwoWay}" Margin="3"></ComboBox> 

下面是視圖模型代碼：

private string[] types = new string[] { "A", "B" }; 

private string application; 

public ObservableCollection<string> Applications { get; private set; } 

public Const() { 
     this.Applications = new ObservableCollection<string>(this.types.ToList()); 
    } 

public string Application { 
     get { 
      this.application = this.applicationSpecificRequirements.ContainsKey(Resources.ApplicationKey) ? this.applicationSpecificRequirements[Resources.ApplicationKey] : this.Applications[0]; 
      return this.application; 
     } 

     set { 
      if (this.exchangeViewModel.CheckIfApplicationNameExistsOrIsEmptyAndAssign(this.InstanceName, value)) { 
       System.Windows.Application.Current.Dispatcher.BeginInvoke(
        new Action(() => { 
         this.applicationSpecificRequirements[Resources.ApplicationKey] = this.application; 
         ((IHaveOnPropertyChangedMethod) this).OnPropertyChanged("Application"); 
        }), DispatcherPriority.ContextIdle, null); 

       return; 
      } 

      this.applicationSpecificRequirements[Resources.ApplicationKey] = value; 
     } 
    } 

Answer 1

看起來像你在屬性setter最後一行缺少OnPropertyChanged（...）。