获取Enum值的属性

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

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;

2012-02-14 11:52:03

其他回答

感谢Bryan Rowe和AdamCrawford的回答!

但是如果有人需要方法来获取描述(而不是扩展)，你可以使用它:

string GetEnumDiscription(Enum EnumValue)
        {
            var type = EnumValue.GetType();
            var memInfo = type.GetMember(EnumValue.ToString());
            var attributes = memInfo[0].GetCustomAttributes(typeof(DescriptionAttribute), false);
            return (attributes.Length > 0) ? ((DescriptionAttribute)attributes[0]).Description : null;
        }

2020-10-29 08:20:08

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;

2012-02-14 11:52:03

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
}

2014-07-01 12:54:36

或者，你可以这样做:

List<SelectListItem> selectListItems = new List<SelectListItem>();

    foreach (var item in typeof(PaymentTerm).GetEnumValues())
    {
        var type = item.GetType();
        var name = type.GetField(item.ToString()).GetCustomAttributesData().FirstOrDefault()?.NamedArguments.FirstOrDefault().TypedValue.Value.ToString();
        selectListItems.Add(new SelectListItem(name, type.Name));

    }

2019-11-11 15:03:13

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);

2011-02-02 17:30:55

获取Enum值的属性

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