在 ASP.NET Core 1.0 中将 ModelState 与 RedirectToAction 异步使用

Question

我有一个删除对象的方法。删除不拥有视图，并且是 "EditReport" 中的一个 "Delete" 按钮。成功删除 "Report".

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。我从这里拿走了：

我最近转为对控制器、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，我将代码属性重写如下：

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();
    }
}

我觉得这很合乎逻辑。但是这段代码并不像我预期的那样工作。但以下异步属性工作正常：

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();
        }
    }

请问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 - 如您所见。如果你不打算从它继承，他们就会做到 sealed。在这种情况下使用 ActionFilterAttribute 似乎是合适的。事实上 quick look @ the repo 揭示了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 base 调用中可能存在您的自定义实现中缺少的代码。看看 here.

在 ASP.NET Core 1.0 中将 ModelState 与 RedirectToAction 异步使用

Async using ModelState with RedirectToAction in ASP.NET Core 1.0

c#

async-await

asp.net-core

asp.net-core-mvc

asp.net-core-1.0