MVC3,EF,根据枚举生成下拉框,获取枚举的自定义属性值.自动扩展，快速开发。

项目中经常用到枚举,根据枚举定义的下拉框比如用户状态等,就非常麻烦,所以写个根据枚举项自动生成下拉框,并扩展htmlhelper类去显示枚举的值.

定义管理员状态枚举值：

/// <summary>
    /// 管理员状态
    /// </summary>
    public enum ManageState
    {
        /// <summary>
        /// 正常
        /// </summary>
        [Display(Name="正常")]
        Normal = 0,
        /// <summary>
        /// 已禁用
        /// </summary>
        [Display(Name = "已禁用")]
        Stop = 1
    }

更具枚举生成下拉框：

简单helpers 方法:

@*将枚举变为下拉框*@
@helper DropEnumFor(Type enumType,string name="state",KeyValuePair<string,string>? defu=null){
    Dictionary<string, int> dir = new Dictionary<string, int>();
    var discriptType = typeof(System.ComponentModel.DataAnnotations.DisplayAttribute);
    var defultChecked = HttpContext.Current.Request["state"];
    foreach (var filed in enumType.GetFields())
    {
        if (!filed.FieldType.IsEnum) {continue;}
        var val = (int)enumType.InvokeMember(filed.Name, System.Reflection.BindingFlags.GetField, null, null, null);
        var key = "";
        var attrs=filed.GetCustomAttributes(discriptType,true);
        if (attrs.Length > 0)
        {
            key = ((DisplayAttribute)attrs[0]).Name;
        }
        else
        {
            key = filed.Name;
        }
        dir.Add(key, val);
    }
    <select id="@name" name="@name">
        @if (defu != null)
        { 
        <option value="@defu.Value.Value">@defu.Value.Key</option>
        }
            @foreach (var item in dir.OrderByDescending(p=>p.Value))
            {
                var check = string.Empty;
                if (defultChecked == item.Value.ToString())
                { check = "selected=\"true\""; }
            <option value="@item.Value" @check >@item.Key</option>
            }
        </select>
}

全局静态扩展：

/// <summary>
       /// 获取枚举的下拉框
       /// </summary>
       /// <typeparam name="TEnum">枚举类型</typeparam>
       /// <param name="name">空间name属性</param>
       /// <param name="defaultValue">默认值</param>
       /// <returns>select 下拉框</returns>
       public static string DropEnumFor<TEnum>(this HtmlHelper helper, string name = "state", KeyValuePair<string, string>? defaultValue = null)
           where TEnum : struct
       {
           var result = new StringBuilder("<select");
           var enumType = typeof(TEnum);
           var defultChecked = HttpContext.Current.Request["state"];
           Dictionary<string, int> dir = new Dictionary<string, int>();
           var discriptType = typeof(System.ComponentModel.DataAnnotations.DisplayAttribute);
           foreach (var filed in enumType.GetFields())
           {
               if (!filed.FieldType.IsEnum) { continue; }
               var val = (int)enumType.InvokeMember(filed.Name, System.Reflection.BindingFlags.GetField, null, null, null);
               var key = "";
               var attrs = filed.GetCustomAttributes(discriptType, true);
               if (attrs.Length > 0)
               {
                   key = ((DisplayAttribute)attrs[0]).Name;
               }
               else
               {
                   key = filed.Name;
               }
               dir.Add(key, val);
           }
           result.AppendFormat(" id=\"{0}\" name=\"{1}\">", name, name);
           if (defaultValue != null)
           {

           }
           foreach (var item in dir.OrderByDescending(p => p.Value))
           {
               var check=string.Empty;;
               if (defultChecked == item.Value.ToString())
                   check = "selected=\"true\"";
               result.AppendFormat("<option value=\"{0}\" {2}>{1}</option>", item.Value, item.Key, check);
           }
           result.Append("</select>");
           return result.ToString();
       }
    }

扩展htmlhelper进行显示

/// <summary>
       /// 获取枚举的display属性
       /// </summary>
       /// <param name="helper"></param>
       /// <param name="state"></param>
       /// <returns></returns>
       public static string Display<TEnum>(this HtmlHelper helper, TEnum state) where TEnum : struct
       {
           var enumType = typeof(TEnum);
           var discriptType = typeof(System.ComponentModel.DataAnnotations.DisplayAttribute);
           var enumName = enumType.GetEnumName(state);
           var result = enumName;
           var attributes= enumType.GetField(enumName).GetCustomAttributes(discriptType, true);
           if (attributes.Length <= 0) return result;
           var dispay=attributes[0] as System.ComponentModel.DataAnnotations.DisplayAttribute;
           result = dispay == null ? result : dispay.Name;
           return result;
       }

使用方式
下拉框:

@Helpers.DropEnumFor(typeof(ManageState), "state", new KeyValuePair<string, string>("全部", "0"))

显示:

<span>
     [@Html.Display(item.ManageState)]
</span>

注：如果在反射时候加上缓存，效率会提升。