我想知道是否有可能获得枚举值的属性，而不是枚举本身?例如，假设我有以下枚举:
using System.ComponentModel; // for DescriptionAttribute
enum FunkyAttributesEnum
{
[Description("Name With Spaces1")]
NameWithoutSpaces1,
[Description("Name With Spaces2")]
NameWithoutSpaces2
}
我想要的是给定枚举类型，产生枚举字符串值及其描述的二元组。
价值很简单:
Array values = System.Enum.GetValues(typeof(FunkyAttributesEnum));
foreach (int value in values)
Tuple.Value = Enum.GetName(typeof(FunkyAttributesEnum), value);
但我如何获得描述属性的值，以填充Tuple.Desc?如果属性属于枚举本身，我可以想到如何做到这一点，但我不知道如何从枚举的值中获得它。
模型
我们用这个模型来充实我们的价值观
public class MemberTypeModel : IDto
{
public string MemberAttributeName { get; set; }
public string MemberName { get; set; }
public int MemberValue { get; set; }
}
Enum
我们的目标是枚举
public enum MemberType
{
[FieldText("Yönetim Kurul Üyesi")]
BoardManager = 0,
[FieldText("Temsilci")]
Representative = 1,
[FieldText("Üye")]
Member = 2
}
辅助方法
我们将使用helper方法来获取自定义属性对象
public T GetMemberCustomText<T>(MemberType memberType) where T : Attribute
{
var enumType = memberType.GetType();
var name = Enum.GetName(enumType, memberType);
return enumType.GetField(name).GetCustomAttributes(false).OfType<T>().SingleOrDefault();
}
Get方法
首先，我们提取枚举值并将它们转换为枚举类型。然后，通过Linq选择查询我们知道;
MemberAttributeName字段与helper方法，
带有Enum的MemberName字段。GetName方法,
将MemberValue字段转换为int类型，
我们把它填好，然后变成一个清单。
public List<MemberTypeModel> GetMemberTypes()
{
var memberTypes = Enum.GetValues(typeof(MemberType))
.Cast<MemberType>()
.Select(et => new MemberTypeModel
{
MemberAttributeName = GetMemberCustomText<FieldText>(et).Text,
MemberName = Enum.GetName(et.GetType(), et),
MemberValue = (int)et
}).ToList();
return memberTypes;
}
从enum中获取字典。
public static IDictionary<string, int> ToDictionary(this Type enumType)
{
return Enum.GetValues(enumType)
.Cast<object>()
.ToDictionary(v => ((Enum)v).ToEnumDescription(), k => (int)k);
}
现在把它叫做…
var dic = typeof(ActivityType).ToDictionary();
枚举描述Ext方法
public static string ToEnumDescription(this Enum en) //ext method
{
Type type = en.GetType();
MemberInfo[] memInfo = type.GetMember(en.ToString());
if (memInfo != null && memInfo.Length > 0)
{
object[] attrs = memInfo[0].GetCustomAttributes(typeof(DescriptionAttribute), false);
if (attrs != null && attrs.Length > 0)
return ((DescriptionAttribute)attrs[0]).Description;
}
return en.ToString();
}
public enum ActivityType
{
[Description("Drip Plan Email")]
DripPlanEmail = 1,
[Description("Modification")]
Modification = 2,
[Description("View")]
View = 3,
[Description("E-Alert Sent")]
EAlertSent = 4,
[Description("E-Alert View")]
EAlertView = 5
}
下面是从Display属性获取信息的代码。它使用泛型方法检索属性。如果没有找到该属性，它将枚举值转换为字符串，将pascal/camel大小写转换为标题大小写(此处获得的代码)
public static class EnumHelper
{
// Get the Name value of the Display attribute if the
// enum has one, otherwise use the value converted to title case.
public static string GetDisplayName<TEnum>(this TEnum value)
where TEnum : struct, IConvertible
{
var attr = value.GetAttributeOfType<TEnum, DisplayAttribute>();
return attr == null ? value.ToString().ToSpacedTitleCase() : attr.Name;
}
// Get the ShortName value of the Display attribute if the
// enum has one, otherwise use the value converted to title case.
public static string GetDisplayShortName<TEnum>(this TEnum value)
where TEnum : struct, IConvertible
{
var attr = value.GetAttributeOfType<TEnum, DisplayAttribute>();
return attr == null ? value.ToString().ToSpacedTitleCase() : attr.ShortName;
}
/// <summary>
/// Gets an attribute on an enum field value
/// </summary>
/// <typeparam name="TEnum">The enum type</typeparam>
/// <typeparam name="T">The type of the attribute you want to retrieve</typeparam>
/// <param name="value">The enum value</param>
/// <returns>The attribute of type T that exists on the enum value</returns>
private static T GetAttributeOfType<TEnum, T>(this TEnum value)
where TEnum : struct, IConvertible
where T : Attribute
{
return value.GetType()
.GetMember(value.ToString())
.First()
.GetCustomAttributes(false)
.OfType<T>()
.LastOrDefault();
}
}
这是字符串转换为title case的扩展方法:
/// <summary>
/// Converts camel case or pascal case to separate words with title case
/// </summary>
/// <param name="s"></param>
/// <returns></returns>
public static string ToSpacedTitleCase(this string s)
{
//https://stackoverflow.com/a/155486/150342
CultureInfo cultureInfo = Thread.CurrentThread.CurrentCulture;
TextInfo textInfo = cultureInfo.TextInfo;
return textInfo
.ToTitleCase(Regex.Replace(s,
"([a-z](?=[A-Z0-9])|[A-Z](?=[A-Z][a-z]))", "$1 "));
}
流利的一句话…
这里我使用的DisplayAttribute包含Name和Description属性。
public static DisplayAttribute GetDisplayAttributesFrom(this Enum enumValue, Type enumType)
{
return enumType.GetMember(enumValue.ToString())
.First()
.GetCustomAttribute<DisplayAttribute>();
}
例子
public enum ModesOfTransport
{
[Display(Name = "Driving", Description = "Driving a car")] Land,
[Display(Name = "Flying", Description = "Flying on a plane")] Air,
[Display(Name = "Sea cruise", Description = "Cruising on a dinghy")] Sea
}
void Main()
{
ModesOfTransport TransportMode = ModesOfTransport.Sea;
DisplayAttribute metadata = TransportMode.GetDisplayAttributesFrom(typeof(ModesOfTransport));
Console.WriteLine("Name: {0} \nDescription: {1}", metadata.Name, metadata.Description);
}
输出
Name: Sea cruise
Description: Cruising on a dinghy
这段代码应该为任何枚举提供了一个不错的扩展方法，使您可以检索泛型属性。我相信它与上面的lambda函数不同，因为它使用起来更简单，而且稍微-你只需要传入泛型类型。
public static class EnumHelper
{
/// <summary>
/// Gets an attribute on an enum field value
/// </summary>
/// <typeparam name="T">The type of the attribute you want to retrieve</typeparam>
/// <param name="enumVal">The enum value</param>
/// <returns>The attribute of type T that exists on the enum value</returns>
/// <example><![CDATA[string desc = myEnumVariable.GetAttributeOfType<DescriptionAttribute>().Description;]]></example>
public static T GetAttributeOfType<T>(this Enum enumVal) where T:System.Attribute
{
var type = enumVal.GetType();
var memInfo = type.GetMember(enumVal.ToString());
var attributes = memInfo[0].GetCustomAttributes(typeof(T), false);
return (attributes.Length > 0) ? (T)attributes[0] : null;
}
}
用法如下:
string desc = myEnumVariable.GetAttributeOfType<DescriptionAttribute>().Description;
