使用嵌入式类使NotifyOfPropertyChange冒泡

Question

所以这是一个使我陷入困境的问题。我正在使用一个嵌入式类结构，该结构需要保持其子对象私有，但应该能够从这些子对象中的数据向上传递某些NotifyOfPropertyChange事件。做这个的最好方式是什么。

[我当前的方法是下面的代码，其中我的SystemViewModel（SystemView）视图具有绑定到CommunicationStatus属性的元素，并且我有一个父类SystemViewModel，它的子类CommunicationManager带有子类Communicator，如下所示。

困难的事情：

1]在这种情况下，必须假定Communicator没有SystemViewModel的可见性，因此不应将Communicator的NotifyOfPropertyChanged(() => CommunicationStatus)属性的set方法中放置Connected作为选择...除非我缺少某些内容很明显。

2）SystemViewModel应该不能直接访问Communicator，因此无法完成从SystemView.xaml到Connected的绑定。

[在我看来，由于在所有类中都实现了Connected，因此PropertyChangedBase中的NotifyOfPropertyChanged事件应该冒充父级，但这并没有发生。希望有帮助！

public class SystemViewModel : PropertyChangedBase
{
    private CommunicationManager CommunicationManager;
    public string CommunicationStatus
    {
        get
        {
            if (CommunicationManager.YepConnected)
            {
                return "Green";
            }
            else
            {
                return "Red";
            }
        }
    }
}

public class CommunicationManager : PropertyChangedBase
{
    private Communicator Communicator;
    public bool YepConnected { get { return Communicator.Connected; } }
}

public class Communicator: PropertyChangedBase
{
    private bool _connected;

    public bool Connected
    {
        get { return _connected; }
        set 
        {
            _connected = value;
            NotifyOfPropertyChange(() => Connected);
        }
    }
}

Answer 1

这是一个如何使用ReactiveUI进行操作的示例

public class SystemViewModel : ReactiveObject
{
    private readonly CommunicationManager communicationManager;
    private readonly ObservableAsPropertyHelper<string> connectionStatus;

    public SystemViewModel( CommunicationManager communicationManager )
    {
        this.communicationManager = communicationManager ?? throw new ArgumentNullException(nameof(communicationManager));
        this.communicationManager
            .WhenAnyValue( e => e.YepConnected, state => state ? "Green" : "Red" )
            .ToProperty( this, e => e.ConnectionStatus, out connectionStatus );
    }
    public string ConnectionStatus => connectionStatus.Value;
}

---

public class CommunicationManager : ReactiveObject
{
    private readonly Communicator communicator;
    private readonly ObservableAsPropertyHelper<bool> yepConnected;

    public CommunicationManager(Communicator communicator)
    {
        this.communicator = communicator ?? throw new ArgumentNullException(nameof(communicator));
        this.communicator
            .WhenAnyValue( e => e.Connected )
            .ToProperty( this, e => e.YepConnected, out yepConnected );
    }
    public bool YepConnected => yepConnected.Value;
}

---

public class Communicator : ReactiveObject
{
    private bool _connected;
    public bool Connected
    {
        get { return _connected; }
        set { this.RaiseAndSetIfChanged( ref _connected, value); }
    }
}

简单测试

var communicator = new Communicator();
var manager = new CommunicationManager(communicator);
var vm = new SystemViewModel( manager );

vm.PropertyChanged += (s,e) => Console.WriteLine( "SystemViewModel.{0} changed", e.PropertyName );

communicator.Connected = true;
communicator.Connected = false;

生成的输出

SystemViewModel.ConnectionStatus已更改SystemViewModel.ConnectionStatus已更改