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。


当前回答

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
}

其他回答

对于一些程序员的幽默,一行代码就像一个笑话:

public static string GetDescription(this Enum value) => value.GetType().GetMember(value.ToString()).First().GetCustomAttribute<DescriptionAttribute>() is DescriptionAttribute attribute ? attribute.Description : string.Empty;

以更易读的形式:

using System;
using System.ComponentModel;
using System.Linq;
using System.Reflection;

public static class EnumExtensions
{
    // get description from enum:

    public static string GetDescription(this Enum value)
    {
        return value.GetType().
            GetMember(value.ToString()).
            First().
            GetCustomAttribute<DescriptionAttribute>() is DescriptionAttribute attribute
            ? attribute.Description
            : throw new Exception($"Enum member '{value.GetType()}.{value}' doesn't have a [DescriptionAttribute]!");
    }

    // get enum from description:

    public static T GetEnum<T>(this string description) where T : Enum
    {
        foreach (FieldInfo fieldInfo in typeof(T).GetFields())
        {
            if (fieldInfo.GetCustomAttribute<DescriptionAttribute>() is DescriptionAttribute attribute && attribute.Description == description)
                return (T)fieldInfo.GetRawConstantValue();
        }

        throw new Exception($"Enum '{typeof(T)}' doesn't have a member with a [DescriptionAttribute('{description}')]!");
    }
}

利用一些较新的c#语言特性,你可以减少行数:

public static TAttribute GetEnumAttribute<TAttribute>(this Enum enumVal) where TAttribute : Attribute
{
    var memberInfo = enumVal.GetType().GetMember(enumVal.ToString());
    return memberInfo[0].GetCustomAttributes(typeof(TAttribute), false).OfType<TAttribute>().FirstOrDefault();
}

public static string GetEnumDescription(this Enum enumValue) => enumValue.GetEnumAttribute<DescriptionAttribute>()?.Description ?? enumValue.ToString();

这应该能满足你的需要。

try
{
  var enumType = typeof(FunkyAttributesEnum);
  var memberInfos = 
  enumType.GetMember(FunkyAttributesEnum.NameWithoutSpaces1.ToString());
  var enumValueMemberInfo = memberInfos.FirstOrDefault(m => 
  m.DeclaringType == enumType);
  var valueAttributes = 
  enumValueMemberInfo.GetCustomAttributes(typeof(DescriptionAttribute), false);
  var description = ((DescriptionAttribute)valueAttributes[0]).Description;
}
catch
{
    return FunkyAttributesEnum.NameWithoutSpaces1.ToString()
}

    public enum DataFilters
    {
        [Display(Name= "Equals")]
        Equals = 1,// Display Name and Enum Name are same 
        [Display(Name= "Does Not Equal")]
        DoesNotEqual = 2, // Display Name and Enum Name are different             
    }

在这个例子中它会产生错误1 "等于"

public static string GetDisplayName(this Enum enumValue)
    {
        var enumMember = enumValue.GetType().GetMember(enumValue.ToString()).First();
        return enumMember.GetCustomAttribute<DisplayAttribute>() != null ? enumMember.GetCustomAttribute<DisplayAttribute>().Name : enumMember.Name;
    }

如果它是相同的返回enum名称而不是显示名称因为 enumMember.GetCustomAttribute () 如果displayname和enum name相同,则返回null .....

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。