兩個視圖模型如何使用catel進行通信wpf

Question

我閱讀文檔如何與視圖模型進行通信，然後嘗試使用它。但是不能改變。就像從GitHub上的例子，我創建CommunicationViewModel：

public abstract class CommunicationViewModel : ViewModelBase 
{ 
    public CommunicationViewModel() 
    { 
     ExampleCommand = new Command(OnExampleCommandExecute); 
    } 

    public string Property 
    { 
     get { return GetValue<string>(PropertyProperty); } 
     set { SetValue(PropertyProperty, value); } 
    } 
    public static readonly PropertyData PropertyProperty = RegisterProperty("Property", typeof(string), null); 

    public void UpdateProperty(string modifier) 
    { 
     Property = modifier.ToString(); 
    } 

    public Command ExampleCommand { get; private set; } 

    private void OnExampleCommandExecute() 
    { 
     ExecuteCommand(); 
    } 

    protected abstract void ExecuteCommand(); 

    protected void AddPropertyChange(string propertyName, Type senderType) 
    { 
     Argument.IsNotNull(() => propertyName); 
     Argument.IsNotNull(() => senderType); 
     // do some stuff 
    } 
} 

然後從OpenViewModel我想將信息發送到MainWindowViewModel。

的OpenViewModel的源代碼：

public class OpenViewModel : CommunicationViewModel 
{ 
    private readonly IMessageService iMessage; 
    private readonly IPleaseWaitService iPleaseWait; 
    private readonly ILanguageService iLanguage; 

    public OpenViewModel(IMessageService iMessageService, IPleaseWaitService iPleaseWaitService, ILanguageService iLanguageService) 
    { 
     Argument.IsNotNull(() => iMessageService); 
     Argument.IsNotNull(() => iPleaseWaitService); 
     Argument.IsNotNull(() => iLanguageService); 

     iMessage = iMessageService; 
     iPleaseWait = iPleaseWaitService; 
     iLanguage = iLanguageService; 

     ChooseDatabaseForOpen = new Command(HandleChooseDatabaseForOpen); 
    } 

    public ObservableCollection<string> Databases 
    { 
     get { return new ObservableCollection<string>(SettingGenerator.ReadFewSameDatabaseSettings("Databases", "Database", "Value")); } 
     set { SetValue(DatabasesProperty, value); } 
    }   
    public static readonly PropertyData DatabasesProperty = RegisterProperty("Databases", typeof(ObservableCollection<string>),() => new ObservableCollection<string>()); 

    public Command ChooseDatabaseForOpen { get; private set; } 

    protected override async Task InitializeAsync() 
    { 
     await base.InitializeAsync(); 
     // TODO: subscribe to events here 
    } 

    protected override async Task CloseAsync() 
    { 
     // TODO: unsubscribe from events here 
     await base.CloseAsync(); 
    } 

    private void HandleChooseDatabaseForOpen() 
    { 
     iPleaseWait.Show(iLanguage.GetString("PleaseWaitMessage")); 
     SettingGenerator.ChangeDatabaseSetting(null, "ActiveDatabase", this.Database); 
     iPleaseWait.Hide(); 
    } 

    protected override void ExecuteCommand() 
    { 
     // InterestedIn does not required any custom logic 
    } 
} 

而且MainWindowViewModel

[InterestedIn(typeof(OpenViewModel))] 
public class MainWindowViewModel : CommunicationViewModel 
{ 
    private const string PATH_TO_CHECKED_IMAGE = @"./../Resources/Images/Icons/Settings/Checked Checkbox.png"; 
    private const string PATH_TO_UNCHECKED_IMAGE = @"./../Resources/Images/Icons/Settings/Checkbox.png"; 

    private readonly IUIVisualizerService iUIVisualizer; 
    private readonly IPleaseWaitService iPleaseWait; 
    private readonly IMessageService iMessage; 
    private readonly IOpenFileService iOpenFile; 
    private readonly ILanguageService iLanguage; 
    private readonly ISplashScreenService iSplashScreen; 

    private readonly string settingFile = AppDomain.CurrentDomain.BaseDirectory + FileConstants.PATH_TO_SETTINGS_FILE; 

    public MainWindowViewModel(IUIVisualizerService iUIVisualizerService, IPleaseWaitService iPleaseWaitService, IMessageService iMessageService, IOpenFileService iOpenFileService, ILanguageService iLanguageService, ISplashScreenService iSplashScreenService) 
    { 
     Argument.IsNotNull(() => iOpenFileService); 
     Argument.IsNotNull(() => iUIVisualizerService); 
     Argument.IsNotNull(() => iMessageService); 
     Argument.IsNotNull(() => iPleaseWaitService); 
     Argument.IsNotNull(() => iLanguageService); 
     Argument.IsNotNull(() => iSplashScreenService); 

     this.iOpenFile = iOpenFileService; 
     this.iUIVisualizer = iUIVisualizerService; 
     this.iMessage = iMessageService; 
     this.iPleaseWait = iPleaseWaitService; 
     this.iLanguage = iLanguageService; 
     this.iSplashScreen = iSplashScreenService; 

     Minimize = new Command(HandleMinimizeCommand); 
     Restore = new Command(HandleRestoreCommand); 
     CloseApplication = new Command(HandleCloseApplicationCommand); 

     if (SettingGenerator.ReadDatabaseSetting(null, "Update") == "Automatic") 
     { 
      this.AutoUpgradeCheckbox = PATH_TO_CHECKED_IMAGE; 
     } 
     else if (SettingGenerator.ReadDatabaseSetting(null, "Update") == "Manual") 
     { 
      this.AutoUpgradeCheckbox = PATH_TO_UNCHECKED_IMAGE; 
     } 

     SelectIconForMainMenuItems(); 

     //this.Property = this.Database; 
    } 

    protected override void OnViewModelPropertyChanged(IViewModel viewModel, string propertyName) 
    { 
     AddPropertyChange(propertyName, viewModel.GetType()); 
    } 

    protected override void ExecuteCommand() 
    { 
     // InterestedIn does not required any custom logic 
    } 
} 

而且從XAML

的的OpenView

<ListView Name="DatabasesListView" MinHeight="150" Width="200" ItemsSource="{Binding Databases}" SelectedItem="{Binding Property}" /> 

的MainWindowView

<Label Content="{Binding Property}" HorizontalAlignment="Center" Margin="0 0 0 0" FontSize="14" /> 

如何溝通這兩個視圖模型。在例子中工作在我的情況下不工作。當我更換Property時，每次都是null。是不是每次都給我一些例外是空的。

編輯：我用了兩個數據窗口，不使用用戶控件

Answer 1

隨着documentation explains，有幾種方法視圖模型之間的通信：

1. 服務
2. InterestedIn（你使用的是什麼）
3. MessageMediator

它看起來像你在做什麼是正確的。如果您覺得它不能按預期工作，請在official tracker中提供一個repro。