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我有一个使用 WPF 和 Prism 的小型应用程序。我有我的外壳和两个模块。我可以以“正常方式”(例如通过单击按钮)在它们之间成功导航,因此我知道它们已正确连接以进行导航。但是,如果我执行一些在完成时触发事件的异步操作,我将无法从该事件处理程序内部导航。我尝试的最后一件事是使用事件聚合将事件发布回 UI 线程,但它仍然无法导航。事件的订阅者成功获取事件并触发 RequestNavigate(...) 但 UI 没有更新。

现在,一些代码:我的第一个模块的视图模型LoginModule

public class LoginViewModel : ViewModelBase, ILoginViewModel, INavigationAware
{
    ...

    [ImportingConstructor]
    public LoginViewModel(IRegionManager regionManager, IUnityContainer container, IEventAggregator eventAggregator)
    {
        _regionManager = regionManager;
        _container = container;
        _eventAggregator = eventAggregator;
    }

    private DelegateCommand _Login;
    public DelegateCommand Login
    {
        get
        {
            if (_Login == null)
                _Login = new DelegateCommand(() => LoginHandler());
            return _Login;
        }
    }
    private void LoginHandler()
    {
        _client = new JabberClient();
        _client.Server = "gmail.com";
        _client.User = Username;
        _client.Password = Password;

        ...

        _client.OnAuthenticate += client_OnAuthenticate;
        _client.Connect();
    }

    private void client_OnAuthenticate(object sender)
    {
        Console.WriteLine("Authenticated!");
        _eventAggregator.GetEvent<UserAuthenticatedEvent>().Publish("");
    }

    public bool IsNavigationTarget(NavigationContext navigationContext)
    {
        return true;
    }
    ...
}

我的第二个模块的 ViewModel RosterModule

public class RosterViewModel : IRosterViewModel, INavigationAware
{
    private readonly IEventAggregator _eventAggregator;
    private readonly IRegionManager _regionManager;

    [ImportingConstructor]
    public RosterViewModel(IRegionManager regionManager, IEventAggregator eventAggregator)
    {
        _regionManager = regionManager;
        _eventAggregator = eventAggregator;

        _eventAggregator.GetEvent<UserAuthenticatedEvent>().Subscribe(o =>
        {
            Console.WriteLine("Requesting navigation...");
            _regionManager.RequestNavigate(RegionNames.ContentRegion, new Uri(WellKnownViewNames.RosterView, UriKind.Relative));
        });
    }

    public bool IsNavigationTarget(NavigationContext navigationContext)
    {
        return true;
    }

    public void OnNavigatedFrom(NavigationContext navigationContext)
    {

    }

    public void OnNavigatedTo(NavigationContext navigationContext)
    {
        Console.WriteLine("I'm here at the RosterViewModel");
    }
}

关于我可能做错了什么的任何提示?

4

1 回答 1

2

来自 OP,

好的,所以在发布几分钟后,我重读了一篇我昨天遇到的文章,看到了我错过的东西......

http://neverindoubtnet.blogspot.com/2009/05/event-aggregator-in-prism-explorer.html

他们解释说,Subscribe 方法的重载之一包括 ThreadOption。

所以:

_eventAggregator.GetEvent<UserAuthenticatedEvent>()
    .Subscribe(
    o =>
    {
        Console.WriteLine("Requesting navigation...");
        _regionManager.RequestNavigate(
            RegionNames.ContentRegion,
            new Uri(WellKnownViewNames.RosterView, UriKind.Relative));
    });

成为:

_eventAggregator.GetEvent<UserAuthenticatedEvent>()
    .Subscribe(
    o =>
    {
        Console.WriteLine("Requesting navigation...");
        _regionManager.RequestNavigate(
            RegionNames.ContentRegion,
            new Uri(WellKnownViewNames.RosterView, UriKind.Relative));
    }, 
    ThreadOption.UIThread);

现在它起作用了!

希望这可以帮助其他人。

享受!

于 2013-12-11T20:56:23.423 回答