具有关键的ViewData的项目“CityId”的类型“System.Int32”的，但必须是类型“的IEnumerable <SelectListItem>”我使用的创建页面及其工作有

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> 

相同的代码，但不在编辑页面上。我改变了我的代码，但仍未提交数据。虽然时间过得还可以。

Answer 1

您传递null作为Html.DropDownList的元素。在这种情况下，引擎从ViewData字典中的“CityId”的键下选取元素。我假设有一个Int32类型的对象（即ViewData [“CityId”]）。这是默认行为。

Answer 2

下面的代码是使用空的DropDownList的例子：

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

来填充相关数据，你可以使用ViewBag发送数据一个DropDownList。

例子：

首先，你需要到市疮列表分为ViewBag.City。

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

然后你可以使用ViewBag.City到DropDownList。

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