c# - 将 Command CanExecute 和 Executed 处理程序置于主窗口类之外的问题

Question

基本上，我已经为分配给 Window.CommandBindings 的命令本身获得了一个命令绑定(bind):

<CommandBinding Command="local:TimerViewModel.AddTimer" 
    CanExecute="local:TimerViewModel.AddTimer_CanExecute" 
    Executed="local:TimerViewModel.AddTimer_Executed" />

local是默认生成的命名空间，指向应用的命名空间。我在这里想要实现的是在 TimerViewModel 中处理命令，但我不断收到以下错误:

CanExecute="local:TimerViewModel.AddTimer_CanExecute" is not valid. 'local:TimerViewModel.AddTimer_CanExecute' is not a valid event handler method name. Only instance methods on the generated or code-behind class are valid.

虽然 TimerViewModel 非常简单，但我相信我遗漏了一些东西:

public class TimerViewModel : ViewModelBase
{
    public TimerViewModel()
    {
        _timers = new ObservableCollection<TimerModel>();
        _addTimer = new RoutedUICommand("Add Timer", "AddTimer", GetType());
    }

    private ObservableCollection<TimerModel> _timers;

    public ObservableCollection<TimerModel> Timers
    {
        get { return _timers; }
    }

    private static RoutedUICommand _addTimer;

    public static RoutedUICommand AddTimer
    {
        get { return _addTimer; }
    }

    public void AddTimer_CanExecute(object sender, CanExecuteRoutedEventArgs e)
    {
        e.CanExecute = true;
    }

    public void AddTimer_Executed(object sender, ExecutedRoutedEventArgs e)
    {
        _timers.Add(new TimerModel(TimeSpan.FromSeconds((new Random()).Next())));
    }
}

谁能指出我犯的错误？

Answer 1

另请查看 Josh Smith 的 RelayCommand .使用它可以让你像这样写上面的内容:

public class TimerViewModel : ViewModelBase {
    public TimerViewModel() {
        Timers = new ObservableCollection<TimerModel>();
        AddTimerCommand = new RelayCommand(() => AddTimer());
    }

    public ObservableCollection<TimerModel> Timers {
        get;
        private set;
    }

    public ICommand AddTimerCommand {
        get;
        private set;
    }

    private void AddTimer() {
        Timers.Add(new TimerModel(TimeSpan.FromSeconds((new Random()).Next())));
    }
}