无法从 'System.Collections.Generic.IEnumerable 转换<system.web.mvc.selectlistitem>在将 ViewData 用于 @Html.DropDownListFor 时，将 ' 转换为 'string'</system.web.mvc.selectlistitem>

Question

I've found many posts regarding the same questions but none of them were with view data and connected with a repository. I need to use only one class no separate class for Countries and Gender , please.

Error:

Controller

[HttpGet]
        public ActionResult Member(int? MemberId)
        {
            if (MemberId == null)
            {
                Member m = new Member();
                ViewData["CountriesList"] = _dal.GetCountryList();
                ViewData["GenderList"] = _dal.GetGenderList();
                return View(m);
            }
            var data = _dal.GetMemberData(MemberId);
            if (data == null)
            {
                return View();
            }

            return View(data);
        }

Class

public string Country { get; set; }
public string Gender { get; set; }
public string Address { get; set; }
public int Phone { get; set; }
public IEnumerable<SelectListItem> _CountriesList { get; set; }
public IEnumerable<SelectListItem> _GenderList { get; set; }

View

 <div class="col-md-8">
                <div class="col-md-4">
                    <label id="country">Country</label>
                    @Html.DropDownListFor(m => m.Country, Model._CountriesList, ViewData["CountriesList"] as IEnumerable<SelectListItem>, new { @class = "form-control", placeholder = "-- Select Country --" })
                </div>
                <div class="col-md-4">
                    <label id="gender">Gender</label><br />
                    @Html.DropDownListFor(m => m.Gender, Model._GenderList, ViewData["GenderList"] as IEnumerable<SelectListItem>, new { @class = "form-control", placeholder = "-- Select Gender --" })
                </div>
            </div>

Repository

[public IEnumerable<SelectListItem> GetCountryList()
        {
             var _country = new List<SelectListItem>();
            using (SqlConnection con = new SqlConnection(connectionString))
            {
                SqlCommand cmd = new SqlCommand("sp_CountryList", con);
                cmd.CommandType = CommandType.StoredProcedure;
                cmd.Parameters.AddWithValue("@Flag", "getCountryList");
                con.Open();
                SqlDataReader sdr = cmd.ExecuteReader();
                while (sdr.Read())
                {
                    _country.Add(new SelectListItem { Text = sdr["CountryName"].ToString(), Value = sdr["rowId"].ToString() });
                }
                con.Close();
            }
            return _country;
        }]

Answer 1

It seems you are trying to set two datasources to DropDownList at same time which are Model._CountriesList and ViewData["CountriesList"] and it causes build error. There is no such a overload method of DropDownListFor , you have to choose one of them ViewBag or Model .

As I understood correctly, you don't need to use _CountriesList or _GenderList so just remove Model._CountriesList since you use ViewBag :

<div class="col-md-8">
    <div class="col-md-4">
        <label id="country">Country</label>
        @Html.DropDownListFor(m => m.Country, ViewData["CountriesList"] as IEnumerable<SelectListItem>, new { @class = "form-control", placeholder = "-- Select Country --" })
    </div>
    <div class="col-md-4">
        <label id="gender">Gender</label><br />
        @Html.DropDownListFor(m => m.Gender,  ViewData["GenderList"] as IEnumerable<SelectListItem>, new { @class = "form-control", placeholder = "-- Select Gender --" })
    </div>
</div>

For more info, have a look at overloads of DropDownListFor