Question

我是MVC的新手并且还在学习我的方法，我正在尝试填写下拉列表。我有以下代码（型号）：

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();
    }

现在，我在索引控制器中收到以下错误：错误1无法隐式转换类型＆＃39; System.Collections.Generic.IEnumerable＆＃39;到＆＃39; System.Collections.Generic.IEnumerable＆＃39;。存在显式转换（您是否错过了演员？）。我被困在这里，完全不知道该怎么做。任何帮助都会很棒。

Answer 1

Ypu不需要再次创建SelectList，因为您正在重新调动IEnumerable<SelectListItem>，您只需以这种方式返回SelectList：

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


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

或者如果您想要返回IEnumerable<SelectListItem>，那么您可以这样做，无需再次创建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;
    }

将数据库绑定到下拉列表

1 个答案: