mysql - 在 DropDownListFor 中使用枚举值

Question

这是我的 View 模型:

public class EntityViewModel
{
    [Required(ErrorMessage = "Title is required")]
    [StringLength(255)]
    [DisplayName("Title")]
    public string Title { get; set; }
    [Required(ErrorMessage = "Description is required")]
    [DisplayName("Description")]
    public string Description { get; set; }
    [Required]
    public DateTime StartTime { get; set; }
    [Required]
    public DateTime EndTime { get; set; }

    [Required]
    public Decimal InstantSellingPrice { get; set; }
    public Nullable<Decimal> ShippingPrice { get; set; }
    public Int64 Views { get; set; }

    public Int32 UserId { get; set; }

    public int RegionId { get; set; }

    public short SelectCategoryId { get; set; }
    public SelectList Categories { get; set; }

    public IEnumerable<HttpPostedFileBase> Files { get; set; }

    public Condition? Condition { get; set; }
}

public enum Condition
{
    New=1,
    Used=2
}

这是我在 Controller 中创建的操作:

public ActionResult Create()
{
    ViewBag.DropDownList = ReUzze.Helpers.EnumHelper.SelectListFor<Condition>();

    var model = new ReUzze.Models.EntityViewModel
    {
        Categories = new SelectList(this.UnitOfWork.CategoryRepository.Get(), "Id", "Name")
    };
    return View(model);
  }

在我的创建 View 中:

<div class="form-group">
    @Html.LabelFor(model => model.Condition)
    @Html.DropDownListFor(model => model.Condition, ViewBag.DropDownList as SelectList, null)
</div>   

我正在使用您可以找到的 Enumhelper here .

但现在我总是在创建 View 时出现这个错误:

@Html.DropDownListFor(model => model.Condition, ViewBag.DropDownList as SelectList, null)

错误:

Error 1 The call is ambiguous between the following methods or properties: 'System.Web.Mvc.Html.SelectExtensions.DropDownListFor(System.Web.Mvc.HtmlHelper, System.Linq.Expressions.Expression>, System.Collections.Generic.IEnumerable, string)' and 'System.Web.Mvc.Html.SelectExtensions.DropDownListFor(System.Web.Mvc.HtmlHelper, System.Linq.Expressions.Expression>, System.Collections.Generic.IEnumerable, System.Collections.Generic.IDictionary)' c:\Users\Niels\Documents\Visual Studio 2012\Projects\ReUzze\ReUzze\Views\Entity\Create.cshtml 57 30 ReUzze

Answer 1

我通常使用这样的代码。

public static class Enums {

    public static IList<SelectListItem> SelectListOf<TEnum>(bool empty = false)
    {
        var type = typeof(TEnum);
        if (type.IsEnum)
        {
            var list = Enum.GetValues(type)
                .Cast<TEnum>()
                .OrderBy(x => x)
                .Select(x => new SelectListItem { Text = GetDescription(x), Value = x.ToString() })
                .ToList();

            if (empty)
            {
                list.Insert(0, new SelectListItem());
            }

            return list;

        }

        return new List<SelectListItem>();
    }

    private static string GetDescription(object enumerator)
    {
        try
        {
            //get the enumerator type
            Type type = enumerator.GetType();

            //get the member info
            MemberInfo[] memberInfo = type.GetMember(enumerator.ToString());

            //if there is member information
            if (memberInfo != null && memberInfo.Length > 0)
            {
                //we default to the first member info, as it's for the specific enum value
                object[] attributes = memberInfo[0].GetCustomAttributes(typeof(DescriptionAttribute), false);

                //return the description if it's found
                if (attributes != null && attributes.Length > 0)
                    return ((DescriptionAttribute)attributes[0]).Description;
            }

            //if there's no description, return the string value of the enum
            return enumerator.ToString();
        }
        catch (Exception e)
        {
            return string.Empty;
        }
    }

}

然后你可以像这样使用它:

Conditions = Enums.SelectListOf<Condition>();