带有用户友好字符串的Enum ToString

我的枚举包含以下值：

private enum PublishStatusses{
    NotCompleted,
    Completed,
    Error
};

我希望能够以用户友好的方式输出这些值。
我不需要再次从字符串变为值。

我使用DescriptionSystem.ComponentModel命名空间中的属性。只需装饰枚举：

private enum PublishStatusValue
{
    [Description("Not Completed")]
    NotCompleted,
    Completed,
    Error
};

然后使用以下代码进行检索：

public static string GetDescription<T>(this T enumerationValue)
    where T : struct
{
    Type type = enumerationValue.GetType();
    if (!type.IsEnum)
    {
        throw new ArgumentException("EnumerationValue must be of Enum type", "enumerationValue");
    }

    //Tries to find a DescriptionAttribute for a potential friendly name
    //for the enum
    MemberInfo[] memberInfo = type.GetMember(enumerationValue.ToString());
    if (memberInfo != null && memberInfo.Length > 0)
    {
        object[] attrs = memberInfo[0].GetCustomAttributes(typeof(DescriptionAttribute), false);

        if (attrs != null && attrs.Length > 0)
        {
            //Pull out the description value
            return ((DescriptionAttribute)attrs[0]).Description;
        }
    }
    //If we have no description attribute, just return the ToString of the enum
    return enumerationValue.ToString();
}

我用扩展方法做到这一点：

public enum ErrorLevel
{
  None,
  Low,
  High,
  SoylentGreen
}

public static class ErrorLevelExtensions
{
  public static string ToFriendlyString(this ErrorLevel me)
  {
    switch(me)
    {
      case ErrorLevel.None:
        return "Everything is OK";
      case ErrorLevel.Low:
        return "SNAFU, if you know what I mean.";
      case ErrorLevel.High:
        return "Reaching TARFU levels";
      case ErrorLevel.SoylentGreen:
        return "ITS PEOPLE!!!!";
      default:
        return "Get your damn dirty hands off me you FILTHY APE!";
    }
  }
}

也许我缺少了一些东西，但是Enum.GetName怎么了？

public string GetName(PublishStatusses value)
{
    return Enum.GetName(typeof(PublishStatusses), value)
}

编辑：对于用户友好的字符串，您需要通过.resource来完成国际化/本地化，并且可以说，最好使用基于枚举键的固定键而不是基于装饰键属性的固定键。

我创建了一个反向扩展方法，将描述转换回枚举值：

public static T ToEnumValue<T>(this string enumerationDescription) where T : struct
{
    var type = typeof(T);

    if (!type.IsEnum)
        throw new ArgumentException("ToEnumValue<T>(): Must be of enum type", "T");

    foreach (object val in System.Enum.GetValues(type))
        if (val.GetDescription<T>() == enumerationDescription)
            return (T)val;

    throw new ArgumentException("ToEnumValue<T>(): Invalid description for enum " + type.Name, "enumerationDescription");
}

这里最简单的解决方案是使用自定义扩展方法（至少在.NET 3.5中-您可以将其转换为早期框架版本的静态辅助方法）。

public static string ToCustomString(this PublishStatusses value)
{
    switch(value)
    {
        // Return string depending on value.
    }
    return null;
}

我在这里假设您想返回的不是枚举值的实际名称（您可以通过简单地调用ToString来获得）。

另一篇文章是Java。您不能在C＃中的Enums中放置方法。

只是做这样的事情：

PublishStatusses status = ...
String s = status.ToString();

如果要为枚举值使用不同的显示值，则可以使用“属性”和“反射”。

最简单的方法是将扩展类包括到您的项目中，它将与项目中的任何枚举一起使用：

public static class EnumExtensions
{
    public static string ToFriendlyString(this Enum code)
    {
        return Enum.GetName(code.GetType(), code);
    }
}

用法：

enum ExampleEnum
{
    Demo = 0,
    Test = 1, 
    Live = 2
}

...

ExampleEnum ee = ExampleEnum.Live;
Console.WriteLine(ee.ToFriendlyString());

其他一些避免类/引用类型的原始选项：

• 数组方法
• 嵌套结构方法

数组方法

private struct PublishStatusses
{
    public static string[] Desc = {
        "Not Completed",
        "Completed",
        "Error"
    };

    public enum Id
    {
        NotCompleted = 0,
        Completed,
        Error
    };
}

用法

string desc = PublishStatusses.Desc[(int)PublishStatusses.Id.Completed];

嵌套结构方法

private struct PublishStatusses
{
    public struct NotCompleted
    {
        public const int Id = 0;
        public const string Desc = "Not Completed";
    }

    public struct Completed
    {
        public const int Id = 1;
        public const string Desc = "Completed";
    }

    public struct Error
    {
        public const int Id = 2;
        public const string Desc = "Error";
    }            
}

用法

int id = PublishStatusses.NotCompleted.Id;
string desc = PublishStatusses.NotCompleted.Desc;

更新（03/09/2018）

扩展方法和上述第一种技术的混合。

我更喜欢将枚举定义在它们“所属”的位置（最接近其来源，而不是在某些常见的全局名称空间中）。

namespace ViewModels
{
    public class RecordVM
    {
        //public enum Enum { Minutes, Hours }
        public struct Enum
        {
            public enum Id { Minutes, Hours }
            public static string[] Name = { "Minute(s)", "Hour(s)" };
        }
    }
}

扩展方法似乎适用于公共区域，并且枚举的“本地化”定义现在使扩展方法更加冗长。

namespace Common
{
    public static class EnumExtensions
    {
        public static string Name(this RecordVM.Enum.Id id)
        {
            return RecordVM.Enum.Name[(int)id];
        }
    }   
}

枚举及其扩展方法的用法示例。

namespace Views
{
    public class RecordView 
    {
        private RecordDataFieldList<string, string> _fieldUnit;

        public RecordView()
        {
            _fieldUnit.List = new IdValueList<string, string>
            {            
                new ListItem<string>((int)RecordVM.Enum.Id.Minutes, RecordVM.Enum.Id.Minutes.Name()),
                new ListItem<string>((int)RecordVM.Enum.Id.Hours, RecordVM.Enum.Id.Hours.Name())
            };
        }

        private void Update()
        {    
            RecordVM.Enum.Id eId = DetermineUnit();

            _fieldUnit.Input.Text = _fieldUnit.List.SetSelected((int)eId).Value;
        }
    }
}

注意：实际上，我决定取消Enum包装程序（和Name数组），因为最好将名称字符串来自资源（即配置文件或DB）而不是硬编码，并且因为最终将扩展方法放在ViewModels命名空间（只是在另一个“ CommonVM.cs”文件中）。再加上整个.Id事情变得分神且麻烦。

namespace ViewModels
{
    public class RecordVM
    {
        public enum Enum { Minutes, Hours }
        //public struct Enum
        //{
        //    public enum Id { Minutes, Hours }
        //    public static string[] Name = { "Minute(s)", "Hour(s)" };
        //}
    }
}

CommonVM.cs

//namespace Common
namespace ViewModels
{
    public static class EnumExtensions
    {
        public static string Name(this RecordVM.Enum id)
        {
            //return RecordVM.Enum.Name[(int)id];
            switch (id)
            {
                case RecordVM.Enum.Minutes: return "Minute(s)";                    
                case RecordVM.Enum.Hours: return "Hour(s)";
                default: return null;
            }
        }
    }   
}

枚举及其扩展方法的用法示例。

namespace Views
{
    public class RecordView 
    {
        private RecordDataFieldList<string, string> _fieldUnit

        public RecordView()
        {
            _fieldUnit.List = new IdValueList<string, string>
            {            
                new ListItem<string>((int)RecordVM.Enum.Id.Minutes, RecordVM.Enum.Id.Minutes.Name()),
                new ListItem<string>((int)RecordVM.Enum.Id.Hours, RecordVM.Enum.Id.Hours.Name())
            };
        }

        private void Update()
        {    
            RecordVM.Enum eId = DetermineUnit();

            _fieldUnit.Input.Text = _fieldUnit.List.SetSelected((int)eId).Value;
        }
    }
}

您可以将Humanizer软件包与Humanize Enums一起使用。一个例子：

enum PublishStatusses
{
    [Description("Custom description")]
    NotCompleted,
    AlmostCompleted,
    Error
};

那么您可以Humanize直接对enum 使用扩展方法：

var st1 = PublishStatusses.NotCompleted;
var str1 = st1.Humanize(); // will result in Custom description

var st2 = PublishStatusses.AlmostCompleted;
var str2 = st2.Humanize(); // will result in Almost completed (calculated automaticaly)

关于Ray Booysen，代码中存在一个错误：带有用户友好字符串的Enum ToString

您需要考虑枚举值的多个属性。

public static string GetDescription<T>(this object enumerationValue)
            where T : struct
    {
        Type type = enumerationValue.GetType();
        if (!type.IsEnum)
        {
            throw new ArgumentException("EnumerationValue must be of Enum type", "enumerationValue");
        }

        //Tries to find a DescriptionAttribute for a potential friendly name
        //for the enum
        MemberInfo[] memberInfo = type.GetMember(enumerationValue.ToString());
        if (memberInfo != null && memberInfo.Length > 0)
        {
            object[] attrs = memberInfo[0].GetCustomAttributes(typeof(DescriptionAttribute), false);

            if (attrs != null && attrs.Length > 0 && attrs.Where(t => t.GetType() == typeof(DescriptionAttribute)).FirstOrDefault() != null)
            {
                //Pull out the description value
                return ((DescriptionAttribute)attrs.Where(t=>t.GetType() == typeof(DescriptionAttribute)).FirstOrDefault()).Description;
            }
        }
        //If we have no description attribute, just return the ToString of the enum
        return enumerationValue.ToString();

public enum MyEnum
{
    [Description("Option One")]
    Option_One
}

public static string ToDescriptionString(this Enum This)
{
    Type type = This.GetType();

    string name = Enum.GetName(type, This);

    MemberInfo member = type.GetMembers()
        .Where(w => w.Name == name)
        .FirstOrDefault();

    DescriptionAttribute attribute = member != null
        ? member.GetCustomAttributes(true)
            .Where(w => w.GetType() == typeof(DescriptionAttribute))
            .FirstOrDefault() as DescriptionAttribute
        : null;

    return attribute != null ? attribute.Description : name;
}

代替使用枚举，而是使用静态类。

更换

private enum PublishStatuses{
    NotCompleted,
    Completed,
    Error
};

与

private static class PublishStatuses{
    public static readonly string NotCompleted = "Not Completed";
    public static readonly string Completed = "Completed";
    public static readonly string Error = "Error";
};

它将像这样使用

PublishStatuses.NotCompleted; // "Not Completed"

使用最常见的“扩展方法”解决方案发布：

私有枚举通常在另一个类中使用。扩展方法解决方案在那里无效，因为它必须在自己的类中。该解决方案可以是私有的，也可以嵌入另一个类中。

我碰巧是VB.NET迷，所以这是我的版本，将DescriptionAttribute方法与扩展方法结合在一起。一，结果：

Imports System.ComponentModel ' For <Description>

Module Module1
  ''' <summary>
  ''' An Enum type with three values and descriptions
  ''' </summary>
  Public Enum EnumType
    <Description("One")>
    V1 = 1

    ' This one has no description
    V2 = 2

    <Description("Three")>
    V3 = 3
  End Enum

  Sub Main()
    ' Description method is an extension in EnumExtensions
    For Each v As EnumType In [Enum].GetValues(GetType(EnumType))
      Console.WriteLine("Enum {0} has value {1} and description {2}",
        v,
        CInt(v),
        v.Description
      )
    Next
    ' Output:
    ' Enum V1 has value 1 and description One
    ' Enum V2 has value 2 and description V2
    ' Enum V3 has value 3 and description Three
  End Sub
End Module

基本内容：一个名为EnumType的枚举，具有三个值V1，V2和V3。“魔术”发生在Sub Main（）的Console.WriteLine调用中，其中最后一个参数为simple v.Description。对于V1，这将返回“一个”，对于V2，将返回“ V2”，对于V3，将返回“三”。这个Description-method实际上是扩展方法，在另一个名为EnumExtensions的模块中定义：

Option Strict On
Option Explicit On
Option Infer Off

Imports System.Runtime.CompilerServices
Imports System.Reflection
Imports System.ComponentModel

Module EnumExtensions
  Private _Descriptions As New Dictionary(Of String, String)

  ''' <summary>
  ''' This extension method adds a Description method
  ''' to all enum members. The result of the method is the
  ''' value of the Description attribute if present, else
  ''' the normal ToString() representation of the enum value.
  ''' </summary>
  <Extension>
  Public Function Description(e As [Enum]) As String
    ' Get the type of the enum
    Dim enumType As Type = e.GetType()
    ' Get the name of the enum value
    Dim name As String = e.ToString()

    ' Construct a full name for this enum value
    Dim fullName As String = enumType.FullName + "." + name

    ' See if we have looked it up earlier
    Dim enumDescription As String = Nothing
    If _Descriptions.TryGetValue(fullName, enumDescription) Then
      ' Yes we have - return previous value
      Return enumDescription
    End If

    ' Find the value of the Description attribute on this enum value
    Dim members As MemberInfo() = enumType.GetMember(name)
    If members IsNot Nothing AndAlso members.Length > 0 Then
      Dim descriptions() As Object = members(0).GetCustomAttributes(GetType(DescriptionAttribute), False)
      If descriptions IsNot Nothing AndAlso descriptions.Length > 0 Then
        ' Set name to description found
        name = DirectCast(descriptions(0), DescriptionAttribute).Description
      End If
    End If

    ' Save the name in the dictionary:
    _Descriptions.Add(fullName, name)

    ' Return the name
    Return name
  End Function
End Module

由于使用Reflection查找属性的速度很慢，因此查找也将缓存在private中Dictionary，该属性按需填充。

（对VB.NET解决方案很抱歉-将其转换为C＃应该相对容易，而我的C＃对于诸如扩展之类的新主题也很生疏）

用示例干净地总结上述建议：

namespace EnumExtensions {

using System;
using System.Reflection;

public class TextAttribute : Attribute {
   public string Text;
   public TextAttribute( string text ) {
      Text = text;
   }//ctor
}// class TextAttribute

public static class EnumExtender {

public static string ToText( this Enum enumeration ) {

   MemberInfo[] memberInfo = enumeration.GetType().GetMember( enumeration.ToString() );

   if ( memberInfo != null && memberInfo.Length > 0 ) {

      object[] attributes = memberInfo[ 0 ].GetCustomAttributes( typeof(TextAttribute),  false );

      if ( attributes != null && attributes.Length > 0 ) {
         return ( (TextAttribute)attributes[ 0 ] ).Text;
      }

   }//if

   return enumeration.ToString();

}//ToText

}//class EnumExtender

}//namespace

用法：

using System;
using EnumExtensions;

class Program {

public enum Appearance {

  [Text( "left-handed" ) ]
  Left,

  [Text( "right-handed" ) ]
  Right,

}//enum

static void Main( string[] args ) {

   var appearance = Appearance.Left;
   Console.WriteLine( appearance.ToText() );

}//Main

}//class

使用Enum.GetName

从上面的链接...

using System;

public class GetNameTest {
    enum Colors { Red, Green, Blue, Yellow };
    enum Styles { Plaid, Striped, Tartan, Corduroy };

    public static void Main() {

        Console.WriteLine("The 4th value of the Colors Enum is {0}", Enum.GetName(typeof(Colors), 3));
        Console.WriteLine("The 4th value of the Styles Enum is {0}", Enum.GetName(typeof(Styles), 3));
    }
}
// The example displays the following output:
//       The 4th value of the Colors Enum is Yellow
//       The 4th value of the Styles Enum is Corduroy

根据此文档：https : //docs.microsoft.com/pt-br/dotnet/api/system.enum.tostring?view=netframework-4.8

可以使用以下格式将枚举数转换为字符串：

public enum Example
{
    Example1,
    Example2
}

Console.WriteLine(Example.Example1.ToString("g"));

//Outputs: "Example1"

您可以在此链接中查看所有可能的格式：https : //docs.microsoft.com/pt-br/dotnet/api/system.string?view=netframework-4.8

这是对Ray Booysen代码的更新，该代码使用通用的GetCustomAttributes方法和LINQ使事情变得更整洁。

    /// <summary>
    /// Gets the value of the <see cref="T:System.ComponentModel.DescriptionAttribute"/> on an struct, including enums.  
    /// </summary>
    /// <typeparam name="T">The type of the struct.</typeparam>
    /// <param name="enumerationValue">A value of type <see cref="T:System.Enum"/></param>
    /// <returns>If the struct has a Description attribute, this method returns the description.  Otherwise it just calls ToString() on the struct.</returns>
    /// <remarks>Based on http://stackoverflow.com/questions/479410/enum-tostring/479417#479417, but useful for any struct.</remarks>
    public static string GetDescription<T>(this T enumerationValue) where T : struct
    {
        return enumerationValue.GetType().GetMember(enumerationValue.ToString())
                .SelectMany(mi => mi.GetCustomAttributes<DescriptionAttribute>(false),
                    (mi, ca) => ca.Description)
                .FirstOrDefault() ?? enumerationValue.ToString();
    }   

更简洁的摘要：

using System;
using System.Reflection;

public class TextAttribute : Attribute
{
    public string Text;
    public TextAttribute(string text)
    {
        Text = text;
    }
}  

public static class EnumExtender
{
    public static string ToText(this Enum enumeration)
    {
        var memberInfo = enumeration.GetType().GetMember(enumeration.ToString());
        if (memberInfo.Length <= 0) return enumeration.ToString();

        var attributes = memberInfo[0].GetCustomAttributes(typeof(TextAttribute), false);
        return attributes.Length > 0 ? ((TextAttribute)attributes[0]).Text : enumeration.ToString();
    }
}

下划线描述的用法相同。

对于标志枚举包括。

    public static string Description(this Enum value)
    {
        Type type = value.GetType();

        List<string> res = new List<string>();
        var arrValue = value.ToString().Split(',').Select(v=>v.Trim());
        foreach (string strValue in arrValue)
        {
            MemberInfo[] memberInfo = type.GetMember(strValue);
            if (memberInfo != null && memberInfo.Length > 0)
            {
                object[] attrs = memberInfo[0].GetCustomAttributes(typeof(DescriptionAttribute), false);

                if (attrs != null && attrs.Length > 0 && attrs.Where(t => t.GetType() == typeof(DescriptionAttribute)).FirstOrDefault() != null)
                {
                    res.Add(((DescriptionAttribute)attrs.Where(t => t.GetType() == typeof(DescriptionAttribute)).FirstOrDefault()).Description);
                }
                else
                    res.Add(strValue);
            }
            else
                res.Add(strValue);
        }

        return res.Aggregate((s,v)=>s+", "+v);
    }

如果您只想在单词之间添加空格，则只需

string res = Regex.Replace(PublishStatusses.NotCompleted, "[A-Z]", " $0").Trim();

我使用一个通用类来存储枚举/描述对，并使用一个嵌套的帮助器类来获取描述。

该枚举：

enum Status { Success, Fail, Pending }

通用类：

注意：由于泛型类不能被枚举约束，所以我改为由struct约束，并在构造函数中检查枚举。

public class EnumX<T> where T : struct
{
    public T Code { get; set; }
    public string Description { get; set; }

    public EnumX(T code, string desc)
    {
        if (!typeof(T).IsEnum) throw new NotImplementedException();

        Code = code;
        Description = desc;
    }

    public class Helper
    {
        private List<EnumX<T>> codes;

        public Helper(List<EnumX<T>> codes)
        {
            this.codes = codes;
        }

        public string GetDescription(T code)
        {
            EnumX<T> e = codes.Where(c => c.Code.Equals(code)).FirstOrDefault();
            return e is null ? "Undefined" : e.Description;
        }
    }
}

用法：

EnumX<Status>.Helper StatusCodes = new EnumX<Status>.Helper(new List<EnumX<Status>>()
        {
            new EnumX<Status>(Status.Success,"Operation was successful"),
            new EnumX<Status>(Status.Fail,"Operation failed"),
            new EnumX<Status>(Status.Pending,"Operation not complete. Please wait...")
        });

        Console.WriteLine(StatusCodes.GetDescription(Status.Pending));

我认为解决问题的最好（也是最简单）的方法是为您的枚举编写一个扩展方法：

public static string GetUserFriendlyString(this PublishStatusses status)
    {

    }

如果您想要完全可定制的内容，请在此处尝试我的解决方案：

http://www.kevinwilliampang.com/post/Mapping-Enums-To-Strings-and-Strings-to-Enums-in-NET.aspx

基本上，该文章概述了如何将Description属性附加到每个枚举，并提供了一种从枚举映射到描述的通用方法。