Question

我有一个DelegateCommand的子类，它失败并出现InvalidProgramException，“Command Language Runtime检测到一个无效的程序。”当我打电话给执行时。

我的子类看起来像这样：

    public class SaveOrderCommand : DelegateCommand<IOrder>
{
    [Dependency]
    public IOrderService OrderService { get; set; }

    public SaveOrderCommand()
        : base(p => this.ExecuteSaveOrder(p), p => this.CanExecuteSaveOrder(p))
    { }

    public bool CanExecuteSaveOrder(IOrder order)
    {
        return true;
    }

    public void ExecuteSaveOrder(IOrder order)
    {
        if (order == null)
            return;

        IProductOrderService productSpecificOrderService = this.OrderService.RegisteredServices[order.GetType()] as IProductOrderService;
        order = productSpecificOrderService.Save(order);
    }
}

我可以看到给基类引用子类中的方法可能是一个问题，但如果这是问题，那么有人可以建议更好的实现吗？

Answer 1

也许您应该自己实施ICommand？你的班级将成为：

public class SaveOrderCommand : ICommand
{
    [Dependency]
    public IOrderService OrderService { get; set; }

    public event EventHandler CanExecuteChanged;

    public bool CanExecute(object parameter)
    {
        return parameter is IOrder;
    }

    public void Execute(object parameter)
    {
        var order = parameter as IOrder;
        if (order == null)
            return;

        IProductOrderService productSpecificOrderService = this.OrderService.RegisteredServices[order.GetType()] as IProductOrderService;
        order = productSpecificOrderService.Save(order);
    }
}

在DelegateCommand子类上调用Execute时出现InvalidProgramException

1 个答案: