如何在 C# 中为枚举值添加描述以与 ASP.NET MVC 中的下拉列表一起使用？ [复制]

Question

如果我想在我的 ASP.NET MVC 视图中将我的枚举用于下拉列表，以便我可以将枚举值或枚举名称作为选择列表项值，并将更具描述性的文本作为选择列表项文本我该怎么做？

Answer 1

这是一个如何做到这一点的示例：

public enum ExampleEnum
{
    [ComponentModel.Description("Example One")]
    ExampleOne,
    [ComponentModel.Description("Example Two")]
    ExampleTwo,
    [ComponentModel.Description("Example Three")]
    ExampleThree,
    [ComponentModel.Description("Example Four")]
    ExampleFour,
    ExampleWithNoDescription
}

@using Mvc4Scratch.Web.Helpers
@model Mvc4Scratch.Web.ViewModels.EnumExampleViewModel

@{
    ViewBag.Title = "EnumDropDownExample";
}

<h2>@Model.ExampleTitle</h2>

<div>
    @Html.LabelFor(model => model.ExampleEnum)
    @Html.EnumDropDownListFor(model => model.ExampleEnum)
</div>

using Mvc4Scratch.Web.Helpers;

namespace Mvc4Scratch.Web.ViewModels
{
    public class EnumExampleViewModel
    {
        public string ExampleTitle { get; set; }

        public ExampleEnum ExampleEnum { get; set; }
    }
}

using System;
using System.ComponentModel;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
using System.Web.Mvc;
using System.Web.Mvc.Html;

namespace Mvc4Scratch.Web.Helpers
{
    public static class Extensions
    {
        public static string GetName(this Enum value)
        {
            return Enum.GetName(value.GetType(), value);
        }

        public static string GetDescription(this Enum value)
        {
            var fieldInfo = value.GetType().GetField(value.GetName());
            var descriptionAttribute = fieldInfo.GetCustomAttributes(typeof(DescriptionAttribute), false).FirstOrDefault() as DescriptionAttribute;
            return descriptionAttribute == null ? value.GetName() : descriptionAttribute.Description;
        }

        public static MvcHtmlString EnumDropDownListFor<TModel, TEnum>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TEnum>> enumAccessor)
        {
            var propertyInfo = enumAccessor.ToPropertyInfo();
            var enumType = propertyInfo.PropertyType;
            var enumValues = Enum.GetValues(enumType).Cast<Enum>();
            var selectItems = enumValues.Select(s => new SelectListItem
                                                     {
                                                         Text = s.GetDescription(),
                                                         Value = s.ToString()
                                                     });

            return htmlHelper.DropDownListFor(enumAccessor, selectItems);
        }

        public static PropertyInfo ToPropertyInfo(this LambdaExpression expression)
        {
            var memberExpression = expression.Body as MemberExpression;
            return (memberExpression == null) ? null : memberExpression.Member as PropertyInfo;
        }
    }
}