我有一个公共(public)枚举，如下所示:

public enum occupancyTimeline
{
    TwelveMonths,
    FourteenMonths,
    SixteenMonths,
    EighteenMonths
}

我将把它用于 DropDown 菜单，如下所示:

@Html.DropDownListFor(model => model.occupancyTimeline, 
   new SelectList(Enum.GetValues(typeof(CentralParkLCPreview.Models.occupancyTimeline))), "")

现在我正在寻找这样的地方来拥有我的值(value)观

12 个月、14 个月、16 个月、18 个月，而不是 TweleveMonths、FourteenMonths、SixteenMonths、EighteenMonths

我将如何完成这个？

最佳答案

我给自己做了一个扩展方法，我现在在每个项目中都使用它:

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

namespace App.Extensions
{
    public static class EnumExtensions
    {
        public static SelectList ToSelectList(Type enumType)
        {
            return new SelectList(ToSelectListItems(enumType));
        }

        public static List<SelectListItem> ToSelectListItems(Type enumType, Func<object, bool> itemSelectedAction = null)
        {
            var arr = Enum.GetValues(enumType);
            return (from object item in arr
                    select new SelectListItem
                    {
                        Text = ((Enum)item).GetDescriptionEx(typeof(MyResources)),
                        Value = ((int)item).ToString(),
                        Selected = itemSelectedAction != null && itemSelectedAction(item)
                    }).ToList();
        }

        public static string GetDescriptionEx(this Enum @this)
        {
            return GetDescriptionEx(@this, null);
        }

        public static string GetDescriptionEx(this Enum @this, Type resObjectType)
        {
            // If no DescriptionAttribute is present, set string with following name
            // "Enum_<EnumType>_<EnumValue>" to be the default value.
            // Could also make some code to load value from resource.

            var defaultResult = $"Enum_{@this.GetType().Name}_{@this}";

            var fi = @this.GetType().GetField(@this.ToString());
            if (fi == null)
                return defaultResult;

            var customAttributes = fi.GetCustomAttributes(typeof(DescriptionAttribute), false);
            if (customAttributes.Length <= 0 || customAttributes.IsNot<DescriptionAttribute[]>())
            {
                if (resObjectType == null)
                    return defaultResult;

                var res = GetFromResource(defaultResult, resObjectType);
                return res ?? defaultResult;
            }

            var attributes = (DescriptionAttribute[])customAttributes;
            var result = attributes.Length > 0 ? attributes[0].Description : defaultResult;
            return result ?? defaultResult;
        }

        public static string GetFromResource(string defaultResult, Type resObjectType)
        {
            var searchingPropName = defaultResult;
            var props = resObjectType.GetProperties();
            var prop = props.FirstOrDefault(t => t.Name.Equals(searchingPropName, StringComparison.InvariantCultureIgnoreCase));
            if (prop == null)
                return defaultResult;
            var res = prop.GetValue(resObjectType) as string;
            return res;
        }

        public static bool IsNot<T>(this object @this)
        {
            return !(@this is T);
        }
    }
}

然后像这样使用它(例如，在 View.cshtml 中)(为了清楚起见，代码分成两行；也可以做成一行):

// A SelectList without default value selected
var list1 = EnumExtensions.ToSelectListItems(typeof(occupancyTimeline));
@Html.DropDownListFor(model => model.occupancyTimeline, new SelectList(list1), "")

// A SelectList with default value selected if equals "DesiredValue"
// Selection is determined by lambda expression as a second parameter to
// ToSelectListItems method which returns bool.
var list2 = EnumExtensions.ToSelectListItems(typeof(occupancyTimeline), item => (occupancyTimeline)item == occupancyTimeline.DesiredValue));
@Html.DropDownListFor(model => model.occupancyTimeline, new SelectList(list2), "")

更新

根据 Phil 的建议，我更新了上面的代码，可以从某些资源(如果有的话)中读取枚举的显示值。资源中的项目名称应采用 Enum_<EnumType>_<EnumValue> 的形式(例如 Enum_occupancyTimeline_TwelveMonths )。这样您就可以在资源文件中为您的枚举值提供文本，而无需使用某些属性修饰您的枚举值。资源类型 (MyResource) 直接包含在 ToSelectItems 方法中。您可以将其提取为扩展方法的参数。

命名枚举值的另一种方法是应用 Description 属性(无需根据我所做的更改调整代码即可工作)。例如:

public enum occupancyTimeline
{
    [Description("12 Months")]
    TwelveMonths,
    [Description("14 Months")]
    FourteenMonths,
    [Description("16 Months")]
    SixteenMonths,
    [Description("18 Months")]
    EighteenMonths
}

关于c# - 带整数字符串的枚举，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/39354793/