我在我的引导程序中有以下代码:
private SimpleContainer container;
protected override void Configure()
{
container = new SimpleContainer();
container.Singleton<IEventAggregator, EventAggregator>();
container.PerRequest<InitialViewModel>();
}
protected override object GetInstance(Type service, string key)
{
return container.GetInstance(service, key);
}
protected override IEnumerable<object> GetAllInstances(Type service)
{
return container.GetAllInstances(service);
}
protected override void BuildUp(object instance)
{
container.BuildUp(instance);
}
在OnStartup方法中,我调用了DisplayRooViewFor方法:
DisplayRooViewFor
。protected override void OnStartup(object sender, StartupEventArgs e)
{
DisplayRootViewFor<InitialViewModel>();
}
这是InitialViewModel:
private IEventAggregator eventAggregator;
public InitialViewModel(IEventAggregator ea)
{
eventAggregator = ea;
}
不幸的是,它抛出了一个NullReferenceException:
类型为'System.NullReferenceException'的异常在Caliburn.Micro.Platform.dll中发生,但未在用户代码中处理
我检查了CM的源代码并使用相同的代码进行测试:
protected override void OnStartup(object sender, StartupEventArgs e)
{
var viewModel = IoC.GetInstance(typeof(InitialViewModel), null);
var view = ViewLocator.LocateForModel(viewModel, null, null);
ViewModelBinder.Bind(viewModel, view, null);
var activator = viewModel as IActivate;
if (activator != null)
activator.Activate();
DisplayRootViewFor<InitialViewModel>();
}
奇怪的是,在这些代码行中没有任何异常。 view 和 viewmodel 都有引用,InitialView 的构造函数已被调用,但当它到达并调用 DisplayRootViewFor
时,仍然会抛出异常。
我应该做出哪些改变?