具有鍵「JobTitleID」的ViewData項的類型爲「System.Int32」，但必須是「IEnumerable <SelectListItem>」類型的？

遵循教程，並按照步驟進行，但在編輯字段時出現錯誤。具有鍵「JobTitleID」的ViewData項的類型爲「System.Int32」，但必須是「IEnumerable <SelectListItem>」類型的？

源錯誤：

 </div> 
    <div class="editor-field"> 
     @Html.DropDownList("JobTitleID", String.Empty) 
     @Html.ValidationMessageFor(model => model.JobTitleID) 
    </div>

這裏是我的控制器：

// POST: /Employee/Create 

    [HttpPost] 
    [ValidateAntiForgeryToken] 
    public ActionResult Create([Bind(Include = "SIN, FirstName, MiddleName, LastName, StartDate, Salary, JobTitleID, DepartmentID")] Employee employee) 
    { 
     try 
     { 

      if (ModelState.IsValid) 
      { 
       db.Employees.Add(employee); 
       db.SaveChanges(); 
       return RedirectToAction("Index"); 
      } 
     } 
     catch (DataException dex) 
     { 
      if (dex.InnerException.InnerException.Message.Contains("IX_Employee_SIN")) 
      { 
       ModelState.AddModelError("SIN", "Unable to save changes. Remember, you cannot have duplicate SIN numbers."); 
      } 
      else 
      { 
       ModelState.AddModelError("", "Unable to save changes. Try again, and if the problem persists see your system administrator."); 
      } 
     } 

     DepartmentDropDownList(employee.DepartmentID); 
     JobDropDownList(employee.JobTitleID); 
     return View(employee); 
    } 

    // 
    // GET: /Employee/Edit/5 

    public ActionResult Edit(int id = 0) 
    { 
     Employee employee = db.Employees.Find(id); 
     if (employee == null) 
     { 
      return HttpNotFound(); 
     } 
     DepartmentDropDownList(employee.DepartmentID); 
     JobDropDownList(employee.JobTitleID); 
     return View(employee); 
    } 

    // 
    // POST: /Employee/Edit/5 

    [HttpPost] 
    [ValidateAntiForgeryToken] 
    public ActionResult Edit([Bind(Include = "ID, SIN, FirstName, MiddleName, LastName, StartDate, Salary, JobTitleID, DepartmentID")] Employee employee) 
    { 
     try 
     { 

      if (ModelState.IsValid) 
      { 
       db.Employees.Add(employee); 
       db.SaveChanges(); 
       return RedirectToAction("Index"); 
      } 

     } 
     catch (DataException dex) 
     { 
      if (dex.InnerException.InnerException.Message.Contains("IX_Employee_SIN")) 
      { 
       ModelState.AddModelError("SIN", "Unable to save changes. Remember, you cannot have duplicate SIN numbers."); 
      } 
      else 
      { 
       ModelState.AddModelError("", "Unable to save changes. Try again, and if the problem persists see your system administrator."); 
      } 
     } 

     DepartmentDropDownList(employee.DepartmentID); 
     JobDropDownList(employee.JobTitleID); 
     return View(employee); 
    } 


    private void JobDropDownList(object selectedJob = null) 
    { 
     var dQuery = from d in db.JobTitles 
        orderby d.Title 
        select d; 
     ViewBag.JobID = new SelectList(dQuery, "ID", "Title", selectedJob); 
    } 
    private void DepartmentDropDownList(object selectedDepartment = null) 
    { 
     var dQuery = from d in db.Departments 
        orderby d.DepartmentName 
        select d; 
     ViewBag.DepartmentID = new SelectList(dQuery, "ID", "DepartmentName",selectedDepartment); 
    }

我真的不那麼熟悉MVC，只是認爲我會問這個問題是什麼，以及它如何被修復。

來源

2013-10-14 1011 1110

您正在使用哪個版本的MVC？它看起來像你試圖使用這種擴展方法：http://msdn.microsoft.com/en-us/library/dd504970(v=vs.108).aspx - 也許它是在一個晚於你正在使用的一個？ –

我正在使用mvc 4 –

錯誤提示您試圖將一個整數綁定到期望IEnumerable選擇列表項的下拉列表中 – Adween

ViewBag在內部封裝了ViewData，所以您收到的消息是關於ViewBag的。您已在控制器上設置了ViewBag.JobID，並且您認爲您正嘗試使用另一個密鑰JobTitleID。嘗試使用正確的鍵：

@Html.DropDownList("JobID", String.Empty)

來源

2013-10-14 18:55:47

具有鍵「JobTitleID」的ViewData項的類型爲「System.Int32」，但必須是「IEnumerable <SelectListItem>」類型的？

回答

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