具有關鍵的ViewData的項目「CityId」的類型「System.Int32」的，但必須是類型「的IEnumerable <SelectListItem>」我使用的創建頁面及其工作有

Question

`  public ActionResult Edit(int id = 0) 
    { 
     property property = db.Properties.Find(id); 

     try 
     { 
      ViewBag.City = new SelectList(db.Cities, "CityId", "City", property.CityId); 
      ViewBag.Locality_Id = new SelectList(db.Areas, "Locality_Id", "Locality", property.Locality_Id); 
      ViewBag.citylist = _data.getCity(); 
      ViewBag.typeproperty = _data.TypeProperty(); 
      ViewBag.Rooms = _data.RoomDetails(); 
      ViewBag.bath = _data.Bathroom(); 
      ViewBag.twowheel = _data.twowheeler(); 
      ViewBag.fourwheel = _data.fourwheeler(); 
      ViewBag.dir = _data.Direction(); 
      ViewBag.floor = _data.Flooring(); 
      ViewBag.water = _data.WaterSupplies(); 
      ViewBag.furnish = _data.Furnishes(); 
      ViewBag.Amenities = new SelectList(db.Amenities, "AmenitiesId", "Amenitie"); 
     } 
     catch (Exception ex) 
     { 
      Console.Write(ex.InnerException.StackTrace.ToString()); 
     } 



     if (property == null) 
     { 
      return HttpNotFound(); 
     } 
     return View(property); 
    }`  

<div class="form-box-left"> 
        <h5>* Select The City :</h5> 
       @Html.DropDownList("CityId", null, "Select City", new { @class = "text-box", Id = "City" }) 
        @Html.ValidationMessageFor(model => model.CityId) 
        <h5>* Locality :</h5> 

相同的代碼，但不在編輯頁面上。我改變了我的代碼，但仍未提交數據。雖然時間過得還可以。

Answer 1

您傳遞null作爲Html.DropDownList的元素。在這種情況下，引擎從ViewData字典中的「CityId」的鍵下選取元素。我假設有一個Int32類型的對象（即ViewData [「CityId」]）。這是默認行爲。

Answer 2

下面的代碼是使用空的DropDownList的例子：

@Html.DropDownList("CityId", Enumerable.Empty<SelectListItem>(), "Select City", new { @class = "text-box", Id = "City" }) 

來填充相關數據，你可以使用ViewBag發送數據一個DropDownList。

例子：

首先，你需要到市瘡列表分爲ViewBag.City。

ViewBag.City = new SelectList(cityList, value, text, selectedCity) 

然後你可以使用ViewBag.City到DropDownList。

@Html.DropDownList("CityId", ViewBag.City as SelectList, "Select City", new { @class = "text-box", Id = "City" })