获取枚举值的属性

这应该能满足你的需要。

var type = typeof(FunkyAttributesEnum);
var memInfo = type.GetMember(FunkyAttributesEnum.NameWithoutSpaces1.ToString());
var attributes = memInfo[0].GetCustomAttributes(typeof(DescriptionAttribute), false);
var description = ((DescriptionAttribute)attributes[0]).Description;

这段代码应该为您提供一个很好的任何枚举的小扩展方法,让您检索一个通用属性。我相信它不同于上面的lambda函数,因为它使用起来更简单,而且稍微有点——您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>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;
    }
}

这是使用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);
}

这样称呼它:

string description = targetLevel.GetAttributeValue<DescriptionAttribute, string>(x => x.Description);

我在这里合并了几个答案,以创建一个更具扩展性的解决方案。我提供它只是为了将来对任何人都有帮助。原始过账 here .

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;
    }

}

此解决方案在枚举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联的任何属性。第二个调用专门检索 DescriptionAttribute 然后返回 Description 价值。

例如,考虑使用 说明属性 属性来自 System.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
}

要使用上述扩展方法,现在只需调用以下内容:

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

或

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

除了 AdamCrawford response ,我还创建了一个更专门的扩展方法,提供它来获取描述。

public static string GetAttributeDescription(this Enum enumValue)
{
    var attribute = enumValue.GetAttributeOfType<DescriptionAttribute>();
    return attribute == null ? String.Empty : attribute.Description;
} 

因此,要获取描述,可以使用原始扩展方法作为

string desc = myEnumVariable.GetAttributeOfType<DescriptionAttribute>().Description

或者您可以在这里简单地调用扩展方法,如下所示:

string desc = myEnumVariable.GetAttributeDescription();

希望能让代码更可读。

流畅的一行…

这里我用的是 DisplayAttribute 它包含两个 Name 和 Description 性质。

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);
}

产量

Name: Sea cruise 
Description: Cruising on a dinghy

下面是从显示属性获取信息的代码。它使用一个通用方法来检索属性。如果找不到属性,则将枚举值转换为字符串,并将pascal/camel大小写转换为标题大小写(获取的代码 here )

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();
    }
}

这是字符串转换为标题大小写的扩展方法:

    /// <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 "));
    }

从枚举获取字典。

public static IDictionary<string, int> ToDictionary(this Type enumType)
{
    return Enum.GetValues(enumType)
    .Cast<object>()
    .ToDictionary(v => ((Enum)v).ToEnumDescription(), k => (int)k); 
}

现在这样称呼…

var dic = typeof(ActivityType).ToDictionary();

EnumDeccription 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
}

我实现了这个扩展方法来从枚举值中获取描述。它适用于所有类型的枚举。

public static class EnumExtension
{
    public static string ToDescription(this System.Enum value)
    {
        FieldInfo fi = value.GetType().GetField(value.ToString());
        var attributes = (DescriptionAttribute[])fi.GetCustomAttributes(typeof(DescriptionAttribute), false);
        return attributes.Length > 0 ? attributes[0].Description : value.ToString();
    }
}

这是AdamCrawford答案的.NET核心版本,使用 System.Reflection.TypeExtensions ;

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>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());
        IEnumerable<Attribute> attributes = memInfo[0].GetCustomAttributes(typeof(T), false);
        return (T)attributes?.ToArray()[0];
    }
}

添加我的网络框架和网络核心解决方案。

我将其用于我的网络框架实现:

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";
    }
}

这对NetCore不起作用,因此我将其修改为:

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";
    }
}

枚举示例:

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

静态添加的示例用法:

var myDescription = myEnum.Description();

利用一些较新的C语言功能,您可以减少行数:

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();

此扩展方法将使用其xmlenumattribute获取枚举值的字符串表示形式。如果不存在xmlenumattribute,则返回到enum.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;
}

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);

我这个答案是从一个枚举属性中设置一个组合框,这很好。

然后我需要对相反的代码进行编码,以便从框中获得所选内容并返回正确类型的枚举。

我还修改了代码来处理属性丢失的情况。

为了下一个人的利益,这是我的最终解决方案

public static class Program
{
   static void Main(string[] args)
    {
       // display the description attribute from the enum
       foreach (Colour type in (Colour[])Enum.GetValues(typeof(Colour)))
       {
            Console.WriteLine(EnumExtensions.ToName(type));
       }

       // Get the array from the description
       string xStr = "Yellow";
       Colour thisColour = EnumExtensions.FromName<Colour>(xStr);

       Console.ReadLine();
    }

   public enum Colour
   {
       [Description("Colour Red")]
       Red = 0,

       [Description("Colour Green")]
       Green = 1,

       [Description("Colour Blue")]
       Blue = 2,

       Yellow = 3
   }
}

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);

        // check if no attributes have been specified.
        if (((Array)attributes).Length > 0)
        {
            return (T)attributes[0];
        }
        else
        {
            return 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;
    }

    /// <summary>
    /// Find the enum from the description attribute.
    /// </summary>
    /// <typeparam name="T"></typeparam>
    /// <param name="desc"></param>
    /// <returns></returns>
    public static T FromName<T>(this string desc) where T : struct
    {
        string attr;
        Boolean found = false;
        T result = (T)Enum.GetValues(typeof(T)).GetValue(0);

        foreach (object enumVal in Enum.GetValues(typeof(T)))
        {
            attr = ((Enum)enumVal).ToName();

            if (attr == desc)
            {
                result = (T)enumVal;
                found = true;
                break;
            }
        }

        if (!found)
        {
            throw new Exception();
        }

        return result;
    }
}

}

伙计们,如果有帮助的话,我会和你们分享我的解决方案: 自定义属性定义:

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

现在,因为我在htmlhelper扩展的htmlhelper定义中需要它:

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");
    }
}

希望有帮助

    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             
    }

在这种情况下,它将产生错误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;
    }

因此,如果它是相同的,则返回枚举名称而不是显示名称,因为 EnumMember.getCustomAttribute()。 如果DisplayName和枚举名称相同,则获取空…..

或者,您可以执行以下操作:

Dictionary<FunkyAttributesEnum, string> description = new Dictionary<FunkyAttributesEnum, string>()
    {
      { FunkyAttributesEnum.NameWithoutSpaces1, "Name With Spaces1" },
      { FunkyAttributesEnum.NameWithoutSpaces2, "Name With Spaces2" },
    };

并获得以下描述:

string s = description[FunkyAttributesEnum.NameWithoutSpaces1];

在我看来,这是一种更有效的方式来做你想做的事情,因为不需要反思。

还可以定义枚举值,如 Name_Without_Spaces ,如果需要说明,请使用 Name_Without_Spaces.ToString().Replace('_', ' ') 用空格替换下划线。