7

有这个代码它给了我一个警告：Because this call is not awaited, execution of the current method continues before the call is completed. Consider applying the 'await' operator to the result of the call.

    public async Task<ActionResult> Details(Guid id)
    {
        var calendarEvent = await service.FindByIdAsync(id);
        if (calendarEvent == null) return RedirectToAction<CalendarController>(c => c.Index());
        var model = new CalendarEventPresentation(calendarEvent);
        ViewData.Model = model;
        return View();
    }

    public async Task<RedirectResult> Create(CalendarEventBindingModel binding)
    {
        var model = service.Create(binding);
        await context.SaveChangesAsync();
        return this.RedirectToAction<CalendarController>(c => c.Details(model.CalendarEventID));
    }

如果我确实添加了await运算符，我会得到：

Error CS4034 The 'await' operator can only be used within an async lambda expression. Consider marking this lambda expression with the 'async' modifier.

如果我async像这样添加修饰符：

return this.RedirectToAction<CalendarController>(async c => await c.Details(model.CalendarEventID));

错误是Error CS1989 Async lambda expressions cannot be converted to expression trees

那么如何将强类型的 RedirectToAction（我正在使用 MVC Futures）与异步控制器一起使用？

4

1 回答 1

2

我已经想通了！

我有一个基本控制器，并且我有一个用于异步重定向的扩展方法

protected ActionResult RedirectToAsyncAction<TController>(Expression<Func<TController, Task<ActionResult>>> action)
        where TController : Controller
    {
        Expression<Action<TController>> convertedFuncToAction = Expression.Lambda<Action<TController>>(action.Body, action.Parameters.First());
        return ControllerExtensions.RedirectToAction(this, convertedFuncToAction);
    }

这将防止警告。然后你可以从你的控制器调用 RedirectToAsyncAction。

public ActionResult MyAction()
    {
       // Your code
        return RedirectToAsyncAction<MyController>(c => c.MyAsyncAction(params,..)); // no warnings here
    }
于 2018-08-02T07:31:17.363 回答