c# - 在 ASP.NET Core 1.0 中使用 ModelState 和 RedirectToAction 进行异步

Question

我有一个方法来删除该对象。删除不拥有 View ，是“EditReport”中的“删除”按钮。成功删除“报告”上的重定向后。

[HttpPost]
[Route("{reportId:int}")]
[ValidateAntiForgeryToken]
public async Task<IActionResult> DeleteReport(int reportId)
{
    var success = await _reportService.DeleteReportControlAsync(reportId);
    if (success == false)
    {
        ModelState.AddModelError("Error", "Messages");
        return RedirectToAction("EditReport");
    }
    ModelState.AddModelError("OK", "Messages");
    return RedirectToAction("Report");
}

在 ASP.NET Core 1.0(完整的 .NET Framework)中，我使用以下属性在方法之间保存 ModelState。我从这里获取:https://stackoverflow.com/a/35987804/3878213

我最近转而对 Controller 、服务和存储库使用异步方法。 在我看来，action的属性也应该是异步的。 最初，我重写了代码属性，如下:

public class SetTempDataModelStateAttribute : Attribute, IAsyncActionFilter
    {
        public async Task OnActionExecutionAsync(ActionExecutingContext filterContext, ActionExecutionDelegate next)
        {    
            var controller = filterContext.Controller as Controller;
            var modelState = controller?.ViewData.ModelState;
            if (modelState != null)
            {
                var listError = modelState.ToDictionary(m => m.Key, m => m.Value.Errors
                    .Select(s => s.ErrorMessage)
                    .FirstOrDefault(s => s != null));
                var listErrorJson = await Task.Run(() => JsonConvert.SerializeObject(listError));
                controller.TempData["ModelState"] = listErrorJson;
            }
            await next();
        }
    }
public class RestoreModelStateFromTempDataAttribute : Attribute, IAsyncActionFilter
{
    public async Task OnActionExecutionAsync(ActionExecutingContext filterContext, ActionExecutionDelegate next)
    {
        var controller = filterContext.Controller as Controller;
        var tempData = controller?.TempData?.Keys;
        if (controller != null && tempData != null)
        {
            if (tempData.Contains("ModelState"))
            {
                var modelStateString = controller.TempData["ModelState"].ToString();
                var listError = await Task.Run(() => 
                    JsonConvert.DeserializeObject<Dictionary<string, string>>(modelStateString));
                var modelState = new ModelStateDictionary();
                foreach (var item in listError)
                {
                    modelState.AddModelError(item.Key, item.Value ?? "");
                }

                controller.ViewData.ModelState.Merge(modelState);
            }
        }
        await next();
    }
}

这对我来说似乎很合乎逻辑。但这段代码并没有按照我的预期工作。 但以下异步属性可以正常工作:

public class SetTempDataModelStateAttribute : ActionFilterAttribute
    {
        public override async Task OnActionExecutionAsync(ActionExecutingContext filterContext, ActionExecutionDelegate next)
        {
            await base.OnActionExecutionAsync(filterContext, next);

            var controller = filterContext.Controller as Controller;
            var modelState = controller?.ViewData.ModelState;
            if (modelState != null)
            {
                var listError = modelState.ToDictionary(m => m.Key, m => m.Value.Errors
                    .Select(s => s.ErrorMessage)
                    .FirstOrDefault(s => s != null));
                var listErrorJson = await Task.Run(() => JsonConvert.SerializeObject(listError));
                controller.TempData["ModelState"] = listErrorJson;
            }
            await next();
        }
    }
public class RestoreModelStateFromTempDataAttribute : ActionFilterAttribute
    {
        public override async Task OnActionExecutionAsync(ActionExecutingContext filterContext, ActionExecutionDelegate next)
        {
            await base.OnActionExecutionAsync(filterContext, next);

            var controller = filterContext.Controller as Controller;
            var tempData = controller?.TempData?.Keys;
            if (controller != null && tempData != null)
            {
                if (tempData.Contains("ModelState"))
                {
                    var modelStateString = controller.TempData["ModelState"].ToString();
                    var listError = await Task.Run(() => 
                        JsonConvert.DeserializeObject<Dictionary<string, string>>(modelStateString));
                    var modelState = new ModelStateDictionary();
                    foreach (var item in listError)
                    {
                        modelState.AddModelError(item.Key, item.Value ?? "");
                    }

                    controller.ViewData.ModelState.Merge(modelState);
                }
            }
            await next();
        }
    }

请告诉我这两个选项哪个更正确？为什么第一个选项不起作用？

Answer 1

Please tell me which of the two options more correct.

选项二更正确，因为它确实有效 - 正如您所注意到的。如果您不打算继承它，他们就会将其密封。在这种情况下使用 ActionFilterAttribute 似乎是合适的。事实上quick look @ the repo表明这实际上是一种非常常见的方法。

Why does the first option not work?

它没有调用base调用。关键是您的自定义实现中可能缺少base 调用中的代码。看看here .