即使在使用 TempData.Keep() asp.net 核心 mvc 后也无法多次使用 TempData

Question

我有一个 mvc 项目，它将在我的中间件中传递一个 tempdata["username"] 。但是在 if(tempdata.ContainsKey("username") 中调试我的中间件时，我注意到它只进入该 if 语句一次并且再也不会进入它。我阅读了这篇文章，解释了如何使用 TempData 以及如何保留数据以便能够多次使用它，但在我的情况下它不起作用。为了实现这一目标，我缺少什么吗？

我的应用程序有 4 个页面，在家庭控制器上它会要求我输入用户名。当我这样做时，然后在中间件中传递临时数据并输入 if 语句。当继续 post 方法并在新页面上时，它将不包含任何值。所以基本上在第 3 次请求时，tempdata 被删除。我该如何解决这个问题，以便它可以在我的所有页面中传递？

HomeController:

    public IActionResult Index()
    {
        // Gather IP

       var userip = Request.HttpContext.Connection.RemoteIpAddress;


        _logger.LogInformation("IP address of user logged in: {@IP-Address}", userip);

        // Call AddressService API

         var result = _addressServiceClient.SampleAsync().Result;
        _logger.Log(LogLevel.Information, "Home Page...");

        return View();
    }


        [HttpPost]
        public IActionResult AddressValidate(IFormCollection form)
        {
            // if radio button was checked, perform the following var request.

            // username

            username = form["UserName"];
            TempData["username"] = username;
            TempData.Keep("username");

            //HttpContext.Items["username"] = username;

            string status = form["Status"];

            _logger.LogInformation("Current user logged in: {@Username}", username);
          

            switch (status)
            {
                case "1":
                    _logger.LogInformation("Address entered was valid!");
                    break;
                case "2":
                    _logger.LogError("Address entered was invalid!");
                    ViewBag.Message = string.Format("You did not enter your address correctly! Please enter it again!");
                    return View("Index");
                case "3":
                    _logger.LogError("Invalid Address");
                    throw new Exception("Invalid Address");
                    
            }

            var request = new AddressRequest
            {

                StatusCode = Convert.ToInt32(status),
                Address = "2018 Main St New York City, NY, 10001"
            };


            var result = _addressServiceClient.ValidateAddress(request).Result;


            return RedirectToAction("SecIndex", "Second");
        }

middleware:

    public class CorrelationIdMiddleware
    {
        private readonly RequestDelegate _next;
        private readonly ILogger _logger;
        private readonly ITempDataDictionaryFactory _tempDataDictionaryFactory;
        public CorrelationIdMiddleware(RequestDelegate next, ILoggerFactory loggerFactory, ITempDataDictionaryFactory tempDataDictionaryFactory)
        {
            _next = next;
            _logger = loggerFactory.CreateLogger<CorrelationIdMiddleware>();
            _tempDataDictionaryFactory = tempDataDictionaryFactory;
        }

        public async Task Invoke(HttpContext context)
        {
            string correlationId = null;
            string userName;
            var tempData = _tempDataDictionaryFactory.GetTempData(context);

            var key = context.Request.Headers.Keys.FirstOrDefault(n => n.ToLower().Equals("x-correlation-id"));
            if (!string.IsNullOrWhiteSpace(key))
            {
                correlationId = context.Request.Headers[key];
                _logger.LogInformation("Header contained CorrelationId: {@CorrelationId}", correlationId);
            }
            else
            {
                if (tempData.ContainsKey("username"))
                {
                    userName = tempData["username"].ToString();
                    context.Response.Headers.Append("X-username", userName);
                }

                correlationId = Guid.NewGuid().ToString();
                _logger.LogInformation("Generated new CorrelationId: {@CorrelationId}", correlationId);
            }
            context.Response.Headers.Append("x-correlation-id", correlationId);
            using (LogContext.PushProperty("CorrelationId", correlationId))
            {
                await _next.Invoke(context);
            }
        }
    }

Answer 1

当您总是想为另一个请求保留值时，可以使用 Peek。当保留值取决于附加逻辑时使用 Keep。

在您的情况下，您必须使用 Peek。而不是 var val= TempData["username"] 使用 val = TempData.Peek("username");

当您调用 val= TempData["username"] 时，在后台返回数据后自动调用 TempData.Remove("username").

即使在使用 TempData.Keep() asp.net 核心 mvc 后也无法多次使用 TempData

Unable to use TempData more than once even after using TempData.Keep() asp.net core mvc

html

c#

middleware

asp.net-core-mvc

.net-core