Question

尝试加载Drop，我在视图中收到此错误：值不能为null或为空。参数名称：名称

这是控制器

    static List<AccountList> _acc = new List<AccountList>();
    public ActionResult Index()
    {
        _acc = GetAccounts();
        return View(_acc);
    }
    private List<AccountList> GetAccounts()
    {
        List<AccountList> temp = new List<AccountList>();
        string sSource = "Test";
        string sClinicId = "4";
        string sStatus = null;
        //This is simply retrieving the class from the web service where the list data is stored
        ReconUIDataLayer.ClinicAccts retClinicAccts = new     ReconUIDataLayer.ClinicAccts();

     retClinicAccts = ReconUIDataLayer.UIDataLayer.LoadAccountInfo(sSource, sClinicId, ref sStatus);

        temp = (from rows in retClinicAccts.ClinicAccts
                select new AccountList
                {
                        Text = rows.AcctName.ToString(),
                        Value = rows.AcctName.ToString(),
                }).ToList();
        return temp;
    }

这是视图：

    @model IEnumerable<C1MvcWebApplication3.Models.AccountList>
    @using C1MvcWebApplication3.Models
    @{
        Layout = null;
    }

    <!DOCTYPE html>

    <html>
    <head>
        <meta name="viewport" content="width=device-width" />
        <title>Index</title>
    </head>
    <body>
        <div>
            <table>
                <tr><td>@Html.DropDownList("", new SelectList(Model.Select(x => new { Value = x, Text = x}),"AcctName","AcctName"))</td></tr>
</table>
        </div>
    </body>
    </html>

帮助程序发生错误以创建下拉列表。

Answer 1

我实际上做了两件事来解决这个问题： 1）刚刚将List移动到我的控制器

public ActionResult Index()
{
     List<AccountList> _acc = new List<AccountList>();
    _acc = GetAccounts();
    return View(_acc);

}

我不知何故认为我不需要将List声明移动到ActionResult中，以后可能会因为不使它静止而咬我。

2）在我的视图中更改了呼叫

@Html.DropDownList("AccountList",new SelectList(Model, "Value", "Text"),"-Select")

Answer 2

控制器代码

 readonly DBDashboardEntities DB = new DBDashboardEntities();// DB Entity Object  

   public ActionResult Index()  
   {  
       //using viewdata  
       ViewData["SelectDropDown_List"] =new SelectList(DB.tblStudents.ToList(), "studID", "studName"); 
       //using viewbag  
       ViewBag.SelectDropDownList = new SelectList(DB.tblStudents.ToList(), "studID", "studName");  
       return View();  
   }

查看页面代码：index.cshtml

 <tr>  
     <td>  
        @Html.DropDownListFor(c => c.studName, new SelectList(  
              new List<Object>{   
                   new { value = 0 , text = "Rose"  },  
                   new { value = 1 , text = "John" },  
                   new { value = 2 , text = "Smith"}  
                },  
              "value",  
              "text", 2))  
    </td>   
    <td>  
        @Html.DropDownListFor(c => c.studID, ViewData["SelectDropDown_List"] as SelectList) @*ViewData requires type casting*@
    </td>  
    <td>  
         @Html.DropDownList("SelectDropDownList") @*String must be same as  ViewBag.SelectDropDownList*@ 
    </td>  
 </tr>

MVC：从<list>加载DropDown

2 个答案: