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

我在这里合并了几个答案,以创建一个更具可扩展性的解决方案。我提供这些只是为了将来对其他人有所帮助。原文在此。

using System;
using System.ComponentModel;

public static class EnumExtensions {

    // This extension method is broken out so you can use a similar pattern with 
    // other MetaData elements in the future. This is your base method for each.
    public static T GetAttribute<T>(this Enum value) where T : Attribute {
        var type = value.GetType();
        var memberInfo = type.GetMember(value.ToString());
        var attributes = memberInfo[0].GetCustomAttributes(typeof(T), false);
        return attributes.Length > 0 
          ? (T)attributes[0]
          : null;
    }

    // This method creates a specific call to the above method, requesting the
    // Description MetaData attribute.
    public static string ToName(this Enum value) {
        var attribute = value.GetAttribute<DescriptionAttribute>();
        return attribute == null ? value.ToString() : attribute.Description;
    }

}

这个解决方案在Enum上创建一对扩展方法。第一种方法允许您使用反射来检索与您的值相关的任何属性。第二个调用检索DescriptionAttribute并返回它的Description值。

例如,考虑使用System中的DescriptionAttribute属性。ComponentModel

using System.ComponentModel;

public enum Days {
    [Description("Sunday")]
    Sun,
    [Description("Monday")]
    Mon,
    [Description("Tuesday")]
    Tue,
    [Description("Wednesday")]
    Wed,
    [Description("Thursday")]
    Thu,
    [Description("Friday")]
    Fri,
    [Description("Saturday")]
    Sat
}

要使用上面的扩展方法,你现在只需调用下面的方法:

Console.WriteLine(Days.Mon.ToName());

or

var day = Days.Mon;
Console.WriteLine(day.ToName());

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}')]!");
    }
}

这个扩展方法将使用枚举值的XmlEnumAttribute获得枚举值的字符串表示形式。如果没有XmlEnumAttribute,则返回到枚举. tostring()。

public static string ToStringUsingXmlEnumAttribute<T>(this T enumValue)
    where T: struct, IConvertible
{
    if (!typeof(T).IsEnum)
    {
        throw new ArgumentException("T must be an enumerated type");
    }

    string name;

    var type = typeof(T);

    var memInfo = type.GetMember(enumValue.ToString());

    if (memInfo.Length == 1)
    {
        var attributes = memInfo[0].GetCustomAttributes(typeof(System.Xml.Serialization.XmlEnumAttribute), false);

        if (attributes.Length == 1)
        {
            name = ((System.Xml.Serialization.XmlEnumAttribute)attributes[0]).Name;
        }
        else
        {
            name = enumValue.ToString();
        }
    }
    else
    {
        name = enumValue.ToString();
    }

    return name;
}

朋友们,如果有帮助的话,我将与你们分享我的解决方案: Custom属性的定义:

    [AttributeUsage(AttributeTargets.Field,AllowMultiple = false)]
public class EnumDisplayName : Attribute
{
    public string Name { get; private set; }
    public EnumDisplayName(string name)
    {
        Name = name;
    }
}

现在因为我需要它在HtmlHelper扩展的HtmlHelper定义内:

public static class EnumHelper
{
    public static string EnumDisplayName(this HtmlHelper helper,EPriceType priceType)
    {
        //Get every fields from enum
        var fields = priceType.GetType().GetFields();
        //Foreach field skipping 1`st fieldw which keeps currently sellected value
        for (int i = 0; i < fields.Length;i++ )
        {
            //find field with same int value
            if ((int)fields[i].GetValue(priceType) == (int)priceType)
            {
                //get attributes of found field
                var attributes = fields[i].GetCustomAttributes(false);
                if (attributes.Length > 0)
                {
                    //return name of found attribute
                    var retAttr = (EnumDisplayName)attributes[0];
                    return retAttr.Name;
                }
            }
        }
        //throw Error if not found
        throw new Exception("Błąd podczas ustalania atrybutów dla typu ceny allegro");
    }
}

希望能有所帮助

如果你想要完整的名单你可以这样做

typeof (PharmacyConfigurationKeys).GetFields()
        .Where(x => x.GetCustomAttributes(false).Any(y => typeof(DescriptionAttribute) == y.GetType()))
        .Select(x => ((DescriptionAttribute)x.GetCustomAttributes(false)[0]).Description);

添加我的解决方案的Net Framework和NetCore。

我在我的Net Framework实现中使用了这个:

public static class EnumerationExtension
{
    public static string Description( this Enum value )
    {
        // get attributes  
        var field = value.GetType().GetField( value.ToString() );
        var attributes = field.GetCustomAttributes( typeof( DescriptionAttribute ), false );

        // return description
        return attributes.Any() ? ( (DescriptionAttribute)attributes.ElementAt( 0 ) ).Description : "Description Not Found";
    }
}

这并不适用于NetCore,所以我修改了它,这样做:

public static class EnumerationExtension
{
    public static string Description( this Enum value )
    {
        // get attributes  
        var field = value.GetType().GetField( value.ToString() );
        var attributes = field.GetCustomAttributes( false );

        // Description is in a hidden Attribute class called DisplayAttribute
        // Not to be confused with DisplayNameAttribute
        dynamic displayAttribute = null;

        if (attributes.Any())
        {
            displayAttribute = attributes.ElementAt( 0 );
        }

        // return description
        return displayAttribute?.Description ?? "Description Not Found";
    }
}

枚举的例子:

public enum ExportTypes
{
    [Display( Name = "csv", Description = "text/csv" )]
    CSV = 0
}

使用任何静态添加:

var myDescription = myEnum.Description();