我在我的模型中有一个属性叫做Promotion，它的类型是一个标志enum叫做UserPromotion。枚举成员的显示属性设置如下:
[Flags]
public enum UserPromotion
{
None = 0x0,
[Display(Name = "Send Job Offers By Mail")]
SendJobOffersByMail = 0x1,
[Display(Name = "Send Job Offers By Sms")]
SendJobOffersBySms = 0x2,
[Display(Name = "Send Other Stuff By Sms")]
SendPromotionalBySms = 0x4,
[Display(Name = "Send Other Stuff By Mail")]
SendPromotionalByMail = 0x8
}
现在我想要能够在我的视图中创建一个ul来显示我的Promotion属性的选定值。这就是我到目前为止所做的但问题是，我如何在这里获得显示名称?
<ul>
@foreach (int aPromotion in @Enum.GetValues(typeof(UserPromotion)))
{
var currentPromotion = (int)Model.JobSeeker.Promotion;
if ((currentPromotion & aPromotion) == aPromotion)
{
<li>Here I don't know how to get the display attribute of "currentPromotion".</li>
}
}
</ul>
在Aydin和Todd回答的基础上，下面是一个扩展方法，它还可以让您从资源文件中获得名称
using AppResources;
using System;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Reflection;
using System.Resources;
public static class EnumExtensions
{
public static string GetDisplayName(this Enum enumValue)
{
var enumMember= enumValue.GetType()
.GetMember(enumValue.ToString());
DisplayAttribute displayAttrib = null;
if (enumMember.Any()) {
displayAttrib = enumMember
.First()
.GetCustomAttribute<DisplayAttribute>();
}
string name = null;
Type resource = null;
if (displayAttrib != null)
{
name = displayAttrib.Name;
resource = displayAttrib.ResourceType;
}
return String.IsNullOrEmpty(name) ? enumValue.ToString()
: resource == null ? name
: new ResourceManager(resource).GetString(name);
}
}
然后像这样使用它
public enum Season
{
[Display(ResourceType = typeof(Resource), Name = Season_Summer")]
Summer
}
一行-流畅的语法
public static class Extensions
{
/// <summary>
/// A generic extension method that aids in reflecting
/// and retrieving any attribute that is applied to an `Enum`.
/// </summary>
public static TAttribute GetAttribute<TAttribute>(this Enum enumValue)
where TAttribute : Attribute
{
return enumValue.GetType()
.GetMember(enumValue.ToString())
.First()
.GetCustomAttribute<TAttribute>();
}
}
例子
public enum Season
{
[Display(Name = "It's autumn")]
Autumn,
[Display(Name = "It's winter")]
Winter,
[Display(Name = "It's spring")]
Spring,
[Display(Name = "It's summer")]
Summer
}
public class Foo
{
public Season Season = Season.Summer;
public void DisplayName()
{
var seasonDisplayName = Season.GetAttribute<DisplayAttribute>();
Console.WriteLine("Which season is it?");
Console.WriteLine (seasonDisplayName.Name);
}
}
输出
现在是哪个季节?
现在是夏天
更新
第一个解决方案侧重于从enum中获取显示名称。下面的代码应该是您的问题的确切解决方案。
你可以为枚举使用这个helper类:
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Reflection;
public static class EnumHelper<T>
where T : struct, Enum // This constraint requires C# 7.3 or later.
{
public static IList<T> GetValues(Enum value)
{
var enumValues = new List<T>();
foreach (FieldInfo fi in value.GetType().GetFields(BindingFlags.Static | BindingFlags.Public))
{
enumValues.Add((T)Enum.Parse(value.GetType(), fi.Name, false));
}
return enumValues;
}
public static T Parse(string value)
{
return (T)Enum.Parse(typeof(T), value, true);
}
public static IList<string> GetNames(Enum value)
{
return value.GetType().GetFields(BindingFlags.Static | BindingFlags.Public).Select(fi => fi.Name).ToList();
}
public static IList<string> GetDisplayValues(Enum value)
{
return GetNames(value).Select(obj => GetDisplayValue(Parse(obj))).ToList();
}
private static string lookupResource(Type resourceManagerProvider, string resourceKey)
{
var resourceKeyProperty = resourceManagerProvider.GetProperty(resourceKey,
BindingFlags.Static | BindingFlags.Public, null, typeof(string),
new Type[0], null);
if (resourceKeyProperty != null)
{
return (string)resourceKeyProperty.GetMethod.Invoke(null, null);
}
return resourceKey; // Fallback with the key name
}
public static string GetDisplayValue(T value)
{
var fieldInfo = value.GetType().GetField(value.ToString());
var descriptionAttributes = fieldInfo.GetCustomAttributes(
typeof(DisplayAttribute), false) as DisplayAttribute[];
if (descriptionAttributes[0].ResourceType != null)
return lookupResource(descriptionAttributes[0].ResourceType, descriptionAttributes[0].Name);
if (descriptionAttributes == null) return string.Empty;
return (descriptionAttributes.Length > 0) ? descriptionAttributes[0].Name : value.ToString();
}
}
然后你可以在视图中使用它，如下所示:
<ul>
@foreach (var value in @EnumHelper<UserPromotion>.GetValues(UserPromotion.None))
{
if (value == Model.JobSeeker.Promotion)
{
var description = EnumHelper<UserPromotion>.GetDisplayValue(value);
<li>@Html.DisplayFor(e => description )</li>
}
}
</ul>
