[2014-09-21]如何在 Asp.net Mvc 开发过程中更好的使用Enum

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场景描述

在web开发过程中，有时候需要根据Enum类型生成下拉菜单；

有时候在输出枚举类型的时候，又希望输出对应的更具描述性的字符串。

喜欢直接用中文的请无视本文

不多说，直接看代码。

以下代码借鉴自http://*.com/

本文针对 Aspnet Mvc 4 开发而言

Enum定义

using System.ComponentModel;
namespace xxxxx.yyyyy
{
    public enum EN_ArticleType
    {
        [Description("软装家饰")]
        RuanZhuang=1,

        [Description("家居风水")]
        FengShui,

        [Description("装修技巧")]
        JiQiao,

        [Description("行业动态")]
        DongTai,

        [Description("样板美图")]
        MeiTu,

        [Description("人才招聘")]
        Jobs
    }
}

扩展HtmlHelper

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Linq.Expressions;
using System.Web.Mvc;
using System.Web.Mvc.Html;

namespace xxxx.ExtendMethods
{
    public static class HtmlHelperUtils
    {
        /// <summary>
        /// Creates the DropDown List (HTML Select Element) from LINQ
        /// Expression where the expression returns an Enum type.
        /// </summary>
        /// <typeparam name="TModel">The type of the model.</typeparam>
        /// <typeparam name="TProperty">The type of the property.</typeparam>
        /// <param name="htmlHelper">The HTML helper.</param>
        /// <param name="expression">The expression.</param>
        /// <returns></returns>
        public static MvcHtmlString DropDownListForEnum<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper,
            Expression<Func<TModel, TProperty>> expression)
            where TModel : class
        {
            return htmlHelper.DropDownListForEnum(expression, null);
        }

        public static MvcHtmlString DropDownListForEnum<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper,
            Expression<Func<TModel, TProperty>> expression, object htmlAttributes)
            where TModel : class
        {
            TProperty value = htmlHelper.ViewData.Model == null
                ? default(TProperty)
                : expression.Compile()(htmlHelper.ViewData.Model);
            string selected = value == null ? String.Empty : value.ToString();
            if (htmlAttributes == null)
            {
                return htmlHelper.DropDownListFor(expression, createSelectList(expression.ReturnType, selected));
            }
            else
            {
                return htmlHelper.DropDownListFor(expression, createSelectList(expression.ReturnType, selected), htmlAttributes);
            }
        }

        /// <summary>
        /// Creates the select list.
        /// </summary>
        /// <param name="enumType">Type of the enum.</param>
        /// <param name="selectedItem">The selected item.</param>
        /// <returns></returns>
        private static IEnumerable<SelectListItem> createSelectList(Type enumType, string selectedItem)
        {
            return (from object item in Enum.GetValues(enumType)
                    let fi = enumType.GetField(item.ToString())
                    let attribute = fi.GetCustomAttributes(typeof(DescriptionAttribute), true).FirstOrDefault()
                    let title = attribute == null ? item.ToString() : ((DescriptionAttribute)attribute).Description
                    select new SelectListItem
                    {
                        Value = item.ToString(),
                        Text = title,
                        Selected = selectedItem == item.ToString()
                    }).ToList();
        }
    }
}

视图层输出下拉菜单

 @Html.DropDownListForEnum(model => model.Type, new { @class = "col-sm-2" })

扩展Enum

using System;
using System.ComponentModel;
using System.Reflection;

namespace xxxx.ExtendMethods
{
    public static class EnumUtils
    {
        public static string GetEnumDescription(this Enum value)
        {
            FieldInfo fi = value.GetType().GetField(value.ToString());

            DescriptionAttribute[] attributes =
                (DescriptionAttribute[])fi.GetCustomAttributes(
                typeof(DescriptionAttribute),
                false);

            if (attributes != null &&
                attributes.Length > 0)
                return attributes[0].Description;
            else
                return value.ToString();
        }
    }
}

输出Enum value对应的Description

@item.Type.GetEnumDescription()  //item是实体，Type是EN_ArticleType类型的属性

结束

请自行尝试。

：）