Question

我正试图找到一种方法来在命令的生命周期内更改ReactiveUI ReactiveCommand的谓词：

 public class Form1ViewModel
{
    public Form1ViewModel()
    {
        TestAction = () => Observable.Start(() => { MessageBox.Show("Initial step"); });
        TestCommand = ReactiveCommand.CreateFromObservable(TestAction);
        TestCommand.ThrownExceptions.Subscribe(ex => MessageBox.Show(string.Format("Something went wrong while executing test command: {0}", ex)));
        TestAction = () => Observable.Start(() => { MessageBox.Show("Another step"); });

    }
    public ReactiveCommand TestCommand { get; set; }
    public Func<IObservable<Unit>> TestAction { get; set; }
}

从绑定到此viewmodel的视图执行命令时，它始终显示“Initial step”消息而不是“Another step”。任何想法都将不胜感激。

Answer 1

您将TestAction的当前值传递给CreateFromObservable，然后更改了TestAction的值。那永远不会奏效。

你可以试试。

   at SimpleInjector.Scope.GetScopelessInstance[TImplementation](ScopedRegistration`1 registration)
   at SimpleInjector.Scope.GetInstance[TImplementation](ScopedRegistration`1 registration, Scope scope)
   at SimpleInjector.Advanced.Internal.LazyScopedRegistration`1.GetInstance(Scope scope)
   at lambda_method(Closure )
   at SimpleInjector.InstanceProducer.GetInstance()
   at SimpleInjector.Container.GetInstance(Type serviceType)
   at Service.Core.ResolvingActivator.CreateInstance(Type type) in Service.Core\ResolvingActivator.cs:line 43
   at Service.Core.ResolvingActivator.CreateInstance(String typeName) in Service.Core\ResolvingActivator.cs:line 35
   at Service.Core.ResolvingActivator.CreateInstance[TService](String typeName) in Service.Core\ResolvingActivator.cs:line 69

具有动态谓词的ReactiveUI ReactiveCommand

1 个答案: