如何解决这个修改控制器？答案

【问题标题】：How to solve This modify Controller?如何解决这个修改控制器？
【发布时间】：2014-01-28 00:37:58
【问题描述】：

一切正常我的模型验证状态为真这是我的帖子控制器

[HttpPost]       
    public ActionResult Edit(Problem problem, HttpPostedFileBase fileUpload)
    {
        Problem Edproblem = db.Problems.Find(problem.Id);
        ViewBag.ATMId = new SelectList(db.ATMs, "Id", "AtmNumber", Edproblem.ATM.AtmNumber);
        ViewBag.UserId = WebSecurity.GetUserId(User.Identity.Name);
        ViewBag.ProblemTypeId = new SelectList(db.ProblemTypes, "Id", "Name", Edproblem.ProblemTypeId);
        var bankId = from e in db.ATMs where e.Id == problem.ATMId select e;
        ViewBag.BankId = new SelectList(db.Banks, "Id", "Name", bankId);
        ViewBag.AreaId = new SelectList(db.Areas, "Id", "Name", db.Areas.Where(p => p.Id == Edproblem.ATM.AreaId));
        ViewBag.GovId = new SelectList(db.Governates, "Id", "Name", Edproblem.ATM.Area.GovernateId);

        Problem beforeEdit = db.Problems.AsNoTracking().First(p => p.Id == problem.Id);

        if (ModelState.IsValid)
        {
            DateTime now = DateTime.Now;

            if (!Directory.Exists(Server.MapPath("~/UploadImages/" + now.ToString("yyyy_MM/"))))
            {
                Directory.CreateDirectory(Server.MapPath("~/UploadImages/" + now.ToString("yyyy_MM/")));
            }
            if (!Directory.Exists(Server.MapPath("~/UploadImages/" + now.ToString("yyyy_MM/") + Edproblem.ATMId.ToString())))
            {
                Directory.CreateDirectory(Server.MapPath("~/UploadImages/" + now.ToString("yyyy_MM/") + Edproblem.ATMId.ToString()));
            }
            if (!Directory.Exists(Server.MapPath("~/UploadImages/" + now.ToString("yyyy_MM/") + Edproblem.ATMId.ToString() + now.ToString("/dd/"))))
            {
                Directory.CreateDirectory(Server.MapPath("~/UploadImages/" + now.ToString("yyyy_MM/") + Edproblem.ATMId.ToString() + now.ToString("/dd/")));
            }

            var image = WebImage.GetImageFromRequest();

            if (fileUpload != null)
            {
                string fileName = fileUpload.FileName.ToString();
                fileName = Guid.NewGuid().ToString() + fileName.Substring(fileName.LastIndexOf("."));
                fileName = now.ToString("yyyy_MM/") + problem.ATMId.ToString() + "/" + now.ToString("dd/") + fileName;
                if (fileUpload != null && fileUpload.ContentLength > 0)
                    fileUpload.SaveAs(Server.MapPath("~/UploadImages/" + image));

                image.Save(Server.MapPath("/UploadImages/" + fileName));                   

                problem.ImagePath = fileName;
            }
            else
            {                    
                if (problem.ImagePath == null)
                {
                    var getPath = (from e in db.Problems 
                                  where e.Id == problem.Id
                                  select e.ImagePath).ToList();
                    problem.ImagePath = getPath[0].ToString();
                }
            }
            problem.UserId = WebSecurity.GetUserId(User.Identity.Name);                
            db.Entry(problem).State = EntityState.Modified;                
            db.SaveChanges();
            return RedirectToAction("Index");
        }
        return View(problem);
    }

这是错误，因为它看起来完全正确：

An object with the same key already exists in the ObjectStateManager. The ObjectStateManager cannot track multiple objects with the same key.

【问题讨论】：

如果您不打算使用 Problem 对象，为什么还要在变量 beforeEdit 中加载它？
我正在尝试从存储的现有数据中获取旧值，但失败且错误消息没有变化，您可以说是无用的步骤
你不能用新数据填充 beforeEdit，然后保存那个吗？在没有 AsNoTracking() 的情况下加载它，然后填充 UserId、imagepath 等。
非常感谢，我做了一些改变，它就像你所说的那样工作
太棒了！在下面总结了一个简短的答案。

标签： c# asp.net-mvc-3 entity-framework asp.net-mvc-4

【解决方案1】：

您正在将问题对象加载到变量 beforeEdit 中，并且没有进一步使用它。

如果您尝试使用参数中的新数据更新 beforeEdit，并保存该数据而不是视图返回的对象。

【讨论】：