綁定數據庫到下拉列表

Question

我是MVC的新手，仍然在學習我的方法，我正在填充一個下拉列表。我有以下代碼（模型）：

public class SchoolCodes 
{ 
    public int escuelaCode { get; set; } 
    public string escuelaName { get; set; } 
} 

public class AllSchoolCodes 
{ 
    public List<SchoolCodes> GetSchools() 
    { 
     List<SchoolCodes> Codes = new List<SchoolCodes>(); 
     SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["MCE"].ConnectionString); 
     SqlCommand comm = new SqlCommand("SELECT EscuelaCode, EscuelaName from Escuelas", conn); 
     conn.Open(); 
     using (var dataReader = comm.ExecuteReader()) 
     { 
      while (dataReader.Read()) 
      { 

       SchoolCodes ur = new SchoolCodes(); 
       ur.escuelaCode = Convert.ToInt32(dataReader["EscuelaCode"]); 
       ur.escuelaName = Convert.ToString(dataReader["EscuelaName"]); 
       Codes.Add(ur); 
      } 

     } 
     return Codes; 


    } 
} 
public class GetSchoolCodeViewModel 
{ 

    [Display(Name = "Escuela: ")] 
    public int SelectedEscuelaCode { get; set; } 
    public IEnumerable<SelectListItem> AllSchoolCodes { get; set; } 
} 

控制器：

private IEnumerable<SelectListItem> GetCode() 
    { 
     var dbSchoolCodes = new AllSchoolCodes(); 
     var code = dbSchoolCodes 
        .GetSchools() 
        .Select(x => 
          new SelectListItem 
          { 
           Value = x.escuelaCode.ToString(), 
           Text = x.escuelaName 
          }); 

     return new SelectList(code, "Value", "Text"); 
    } 


public ActionResult Index() 
    { 
     var model = new GetSchoolCodeViewModel 
     { 
     AllSchoolCodes = GetCode() 
     }; 
     return View(model); 
    // return View(); 
    } 

現在，我收到以下錯誤教室後面的指數控制器：錯誤1無法隱式轉換類型「System.Collections中.Generic.IEnumerable'到'System.Collections.Generic.IEnumerable'。存在明確的轉換（您是否缺少演員？）。我被困在這裏，完全不知道該怎麼做。任何幫助都是極好的。

Answer 1

YPU不需要重新創建SelectList因爲你是reutrning IEnumerable<SelectListItem>，你可以簡單地返回SelectList這樣：

private SelectList GetCode() 
{ 
     var dbSchoolCodes = new AllSchoolCodes(); 
     var code = dbSchoolCodes.GetSchools(); 


     return new SelectList(code, "escuelaCode", "escuelaName"); 
} 

，或者如果你想回到IEnumerable<SelectListItem>那麼你可以做這樣沒有必要再次創建SelectList：

private IEnumerable<SelectListItem> GetCode() 
    { 
     var dbSchoolCodes = new AllSchoolCodes(); 
     var code = dbSchoolCodes 
        .GetSchools() 
        .Select(x => 
          new SelectListItem 
          { 
           Value = x.escuelaCode.ToString(), 
           Text = x.escuelaName 
          }); 

     return code; 
    }