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。
或者，你可以这样做:
Dictionary<FunkyAttributesEnum, string> description = new Dictionary<FunkyAttributesEnum, string>()
{
{ FunkyAttributesEnum.NameWithoutSpaces1, "Name With Spaces1" },
{ FunkyAttributesEnum.NameWithoutSpaces2, "Name With Spaces2" },
};
并使用以下语句获取描述:
string s = description[FunkyAttributesEnum.NameWithoutSpaces1];
在我看来，这是一种更有效的方式去做你想要完成的事情，因为不需要思考。
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 "));
}
这是一个使用lambda进行选择的通用实现
public static Expected GetAttributeValue<T, Expected>(this Enum enumeration, Func<T, Expected> expression)
where T : Attribute
{
T attribute =
enumeration
.GetType()
.GetMember(enumeration.ToString())
.Where(member => member.MemberType == MemberTypes.Field)
.FirstOrDefault()
.GetCustomAttributes(typeof(T), false)
.Cast<T>()
.SingleOrDefault();
if (attribute == null)
return default(Expected);
return expression(attribute);
}
这样叫它:
string description = targetLevel.GetAttributeValue<DescriptionAttribute, string>(x => x.Description);
