Getting attributes of Enum s value

Question

I would like to know if it is possible to get attributes of the enum values and not of the enum itself  For example  suppose I have the following enum   using System ComponentModel     for DescriptionAttribute  enum FunkyAttributesEnum        Description  Name With Spaces1        NameWithoutSpaces1           Description  Name With Spaces2        NameWithoutSpaces2     What I want is given the enum type  produce 2-tuples of enum string value and its description   Value was easy   Array values   System Enum GetValues typeof FunkyAttributesEnum    foreach  int value in values      Tuple Value   Enum GetName typeof FunkyAttributesEnum   value     But how do I get description attribute s value  to populate Tuple Desc  I can think of how to do it if the Attribute belongs to the enum itself  but I am at a loss as to how to get it from the value of the enum

User · Answer

You can also define an enum value like Name Without Spaces  and when you want a description use Name Without Spaces ToString   Replace           to replace the underscores with spaces

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Here s the  NET Core version of AdamCrawford s answer  using System Reflection TypeExtensions   public static class EnumHelper            lt summary gt          Gets an attribute on an enum field value          lt  summary gt           lt typeparam name  T  gt The type of the attribute you want to retrieve lt  typeparam gt           lt param name  enumVal  gt The enum value lt  param gt           lt returns gt The attribute of type T that exists on the enum value lt  returns gt           lt example gt string desc   myEnumVariable GetAttributeOfType lt DescriptionAttribute gt    Description  lt  example gt      public static T GetAttributeOfType lt T gt  this Enum enumVal  where T   System Attribute               var type   enumVal GetType            var memInfo   type GetMember enumVal ToString             IEnumerable lt Attribute gt  attributes   memInfo 0  GetCustomAttributes typeof T   false           return  T attributes  ToArray   0

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Alternatively  you could do the following    List lt SelectListItem gt  selectListItems   new List lt SelectListItem gt          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

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I implemented this extension method to get the description from enum values  It works for all kind of enums   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  gt  0   attributes 0  Description   value ToString

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Here is code to get information from a Display attribute  It uses a generic method to retrieve the attribute  If the attribute is not found it converts the enum value to a string with pascal camel case converted to title case  code obtained 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 lt TEnum gt  this TEnum value          where TEnum   struct  IConvertible               var attr   value GetAttributeOfType lt TEnum  DisplayAttribute gt             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 lt TEnum gt  this TEnum value          where TEnum   struct  IConvertible               var attr   value GetAttributeOfType lt TEnum  DisplayAttribute gt             return attr    null   value ToString   ToSpacedTitleCase     attr ShortName                  lt summary gt          Gets an attribute on an enum field value          lt  summary gt           lt typeparam name  TEnum  gt The enum type lt  typeparam gt           lt typeparam name  T  gt The type of the attribute you want to retrieve lt  typeparam gt           lt param name  value  gt The enum value lt  param gt           lt returns gt The attribute of type T that exists on the enum value lt  returns gt      private static T GetAttributeOfType lt TEnum  T gt  this TEnum value          where TEnum   struct  IConvertible         where T   Attribute                return value GetType                        GetMember value ToString                         First                        GetCustomAttributes false                       OfType lt T gt                         LastOrDefault              And this is the extension method for strings for converting to title case            lt summary gt          Converts camel case or pascal case to separate words with title case          lt  summary gt           lt param name  s  gt  lt  param gt           lt returns gt  lt  returns gt      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

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This is how I solved it without using custom helpers or extensions with  NET core 3 1   Class  public enum YourEnum        Display Name    Suryoye means Arameans        SURYOYE   0       Display Name    Oromoye means Syriacs        OROMOYE   1      Razor   using Enumerations  foreach  var name in Html GetEnumSelectList typeof YourEnum           lt h1 gt  name Text lt  h1 gt

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This extension method will obtain a string representation of an enum value using its XmlEnumAttribute  If no XmlEnumAttribute is present  it falls back to enum ToString     public static string ToStringUsingXmlEnumAttribute lt T gt  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

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If your enum contains a value like Equals you might bump into a few bugs using some extensions in a lot of answers here  This is because it is normally assumed that typeof YourEnum  GetMember YourEnum Value  would return only one value  which is the MemberInfo of your enum  Here s a slightly safer version Adam Crawford s answer   public static class AttributeExtensions        region Methods      public static T GetAttribute lt T gt  this Enum enumValue  where T   Attribute               var type   enumValue GetType            var memberInfo   type GetMember enumValue ToString             var member   memberInfo FirstOrDefault m   gt  m DeclaringType    type           var attribute   Attribute GetCustomAttribute member  typeof T   false           return attribute is T    T attribute   null              endregion

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Guys if it helps I will share with you my solution   Definition of Custom attribute         AttributeUsage AttributeTargets Field AllowMultiple   false   public class EnumDisplayName   Attribute       public string Name   get  private set        public EnumDisplayName string name                Name   name            Now because I needed it inside of HtmlHelper definition of HtmlHelper Extension    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  lt  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  gt  0                                          return name of found attribute                     var retAttr    EnumDisplayName attributes 0                       return retAttr Name                                                      throw Error if not found         throw new Exception  Blad podczas ustalania atrybut  w dla typu ceny allegro              Hope it helps

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Adding my solution for Net Framework and NetCore   I used this for my Net Framework implementation   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             This doesn t work for NetCore so I modified it to do this     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             Enumeration Example     public enum ExportTypes        Display  Name    csv   Description    text csv         CSV   0     Sample Usage for either static added     var myDescription   myEnum Description

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Bryan Rowe and AdamCrawford thanks for your answers  But if somebody need method for get Discription  not extension  you can use it  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  gt  0      DescriptionAttribute attributes 0   Description   null

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Get the dictionary from enum   public static IDictionary lt string  int gt  ToDictionary this Type enumType        return Enum GetValues enumType       Cast lt object gt         ToDictionary v   gt    Enum v  ToEnumDescription    k   gt   int k        Now call this like     var dic   typeof ActivityType  ToDictionary      EnumDecription Ext Method  public static string ToEnumDescription this Enum en    ext method       Type type   en GetType        MemberInfo   memInfo   type GetMember en ToString         if  memInfo    null  amp  amp  memInfo Length  gt  0                object   attrs   memInfo 0  GetCustomAttributes typeof DescriptionAttribute   false           if  attrs    null  amp  amp  attrs Length  gt  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

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Taking advantage of some of the newer C  language features  you can reduce the line count   public static TAttribute GetEnumAttribute lt TAttribute gt  this Enum enumVal  where TAttribute   Attribute       var memberInfo   enumVal GetType   GetMember enumVal ToString         return memberInfo 0  GetCustomAttributes typeof TAttribute   false  OfType lt TAttribute gt    FirstOrDefault       public static string GetEnumDescription this Enum enumValue    gt  enumValue GetEnumAttribute lt DescriptionAttribute gt     Description    enumValue ToString

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This piece of code should give you a nice little extension method on any enum that lets you retrieve a generic attribute   I believe it s different to the lambda function above because it s simpler to use and slightly - you only need to pass in the generic type   public static class EnumHelper            lt summary gt          Gets an attribute on an enum field value          lt  summary gt           lt typeparam name  T  gt The type of the attribute you want to retrieve lt  typeparam gt           lt param name  enumVal  gt The enum value lt  param gt           lt returns gt The attribute of type T that exists on the enum value lt  returns gt           lt example gt  lt   CDATA string desc   myEnumVariable GetAttributeOfType lt DescriptionAttribute gt    Description    gt  lt  example gt      public static T GetAttributeOfType lt T gt  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  gt  0     T attributes 0    null

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I ve merged a couple of the answers here to create a little more extensible solution  I m providing it just in case it s helpful to anyone else in the future  Original posting 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 lt T gt  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  gt  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 lt DescriptionAttribute gt             return attribute    null   value ToString     attribute Description             This solution creates a pair of extension methods on Enum  The first allows you to use reflection to retrieve any attribute associated with your value  The second specifically calls retrieves the DescriptionAttribute and returns it s Description value   As an example  consider using the DescriptionAttribute attribute from 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     To use the above extension method  you would now simply call the following   Console WriteLine Days Mon ToName       or  var day   Days Mon  Console WriteLine day ToName

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For some programmer humor  a one liner as a joke  public static string GetDescription this Enum value    gt  value GetType   GetMember value ToString    First   GetCustomAttribute lt DescriptionAttribute gt    is DescriptionAttribute attribute   attribute Description   string Empty   In a more readable form  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 lt DescriptionAttribute gt    is DescriptionAttribute attribute               attribute Description               throw new Exception   quot Enum member   value GetType     value   doesn t have a  DescriptionAttribute   quot                  get enum from description       public static T GetEnum lt T gt  this string description  where T   Enum               foreach  FieldInfo fieldInfo in typeof T  GetFields                          if  fieldInfo GetCustomAttribute lt DescriptionAttribute gt    is DescriptionAttribute attribute  amp  amp  attribute Description    description                  return  T fieldInfo GetRawConstantValue                       throw new Exception   quot Enum   typeof T    doesn t have a member with a  DescriptionAttribute   description      quot

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I this answer to setup a combo box from an enum attributes which was great    I then needed to code the reverse so that I can get the selection from the box and return the enum in the correct type   I also modified the code to handle the case where an attribute was missing  For the benefits of the next person  here is my final solution   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 lt Colour gt  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 lt T gt  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  gt  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 lt DescriptionAttribute gt             return attribute    null   value ToString     attribute Description                  lt summary gt          Find the enum from the description attribute           lt  summary gt           lt typeparam name  T  gt  lt  typeparam gt           lt param name  desc  gt  lt  param gt           lt returns gt  lt  returns gt      public static T FromName lt T gt  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

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Alternatively  you could do the following   Dictionary lt FunkyAttributesEnum  string gt  description   new Dictionary lt FunkyAttributesEnum  string gt                  FunkyAttributesEnum NameWithoutSpaces1   Name With Spaces1             FunkyAttributesEnum NameWithoutSpaces2   Name With Spaces2              And get the description with the following   string s   description FunkyAttributesEnum NameWithoutSpaces1     In my opinion this is a more efficient way of doing what you want to accomplish  as no reflection is needed

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This is a generic implementation using a lambda for the selection  public static Expected GetAttributeValue lt T  Expected gt  this Enum enumeration  Func lt T  Expected gt  expression      where T   Attribute       T attribute         enumeration          GetType            GetMember enumeration ToString             Where member   gt  member MemberType    MemberTypes Field           FirstOrDefault            GetCustomAttributes typeof T   false           Cast lt T gt             SingleOrDefault         if  attribute    null          return default Expected        return expression attribute       Call it like this   string description   targetLevel GetAttributeValue lt DescriptionAttribute  string gt  x   gt  x Description

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Fluent one liner     Here I m using the DisplayAttribute which contains both the Name and Description properties   public static DisplayAttribute GetDisplayAttributesFrom this Enum enumValue  Type enumType        return enumType GetMember enumValue ToString                        First                       GetCustomAttribute lt DisplayAttribute gt           Example  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         Output  Name  Sea cruise  Description  Cruising on a dinghy

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This should do what you need   var enumType   typeof FunkyAttributesEnum   var memberInfos   enumType GetMember FunkyAttributesEnum NameWithoutSpaces1 ToString     var enumValueMemberInfo   memberInfos FirstOrDefault m   gt  m DeclaringType    enumType   var valueAttributes          enumValueMemberInfo GetCustomAttributes typeof DescriptionAttribute   false   var description     DescriptionAttribute valueAttributes 0   Description

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Performance matters  If you want better performance this is the way to go   public static class AdvancedEnumExtensions            lt summary gt          Gets the custom attribute  lt typeparamref name  T   gt  for the enum constant  if such a constant is defined and has such an attribute  otherwise null           lt  summary gt      public static T GetCustomAttribute lt T gt  this Enum value  where T   Attribute               return GetField value   GetCustomAttribute lt T gt  inherit  false                   lt summary gt          Gets the FieldInfo for the enum constant  if such a constant is defined  otherwise null           lt  summary gt      public static FieldInfo GetField this Enum value                ulong u64   ToUInt64 value           return value              GetType                GetFields BindingFlags Public   BindingFlags NonPublic   BindingFlags Static               Where f   gt  ToUInt64 f GetRawConstantValue       u64               FirstOrDefault                    lt summary gt          Checks if an enum constant is defined for this enum value          lt  summary gt      public static bool IsDefined this Enum value                return GetField value     null                  lt summary gt          Converts the enum value to UInt64          lt  summary gt      public static ulong ToUInt64 this Enum value    gt  ToUInt64  object value        private static ulong ToUInt64 object value                switch  Convert GetTypeCode value                         case TypeCode SByte              case TypeCode Int16              case TypeCode Int32              case TypeCode Int64                  return unchecked  ulong Convert ToInt64 value  CultureInfo InvariantCulture                 case TypeCode Byte              case TypeCode UInt16              case TypeCode UInt32              case TypeCode UInt64              case TypeCode Char              case TypeCode Boolean                  return Convert ToUInt64 value  CultureInfo InvariantCulture                default  throw new InvalidOperationException  UnknownEnumType                        Why does this have better performance   Because the built-in methods all use code very similar to this except they also run a bunch of other code we don t care about  C  s Enum code is quite horrible in general   The above code has been Linq-ified and streamlined so it only contains the bits we care about   Why is the built-in code slow   First regarding Enum ToString   -vs- Enum GetName      Always use the latter   Or better yet neither  as will become clear below    ToString   uses the latter internally  but again  also does a bunch of other stuff we don t want  e g  tries to combine flags  print out numbers etc  We are only interested in constants defined inside the enum   Enum GetName in turn gets all fields  creates a string array for all names  uses the above ToUInt64 on all of their RawConstantValues to create an UInt64 array of all values  sorts both arrays according to the UInt64 value  and finally gets the name from the name-array by doing a BinarySearch in the UInt64-array to find the index of the value we wanted      and then we throw the fields and the sorted arrays away use that name to find the field again   One word   Ugh

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And if you want the full list of names you can do something like  typeof  PharmacyConfigurationKeys  GetFields            Where x   gt  x GetCustomAttributes false  Any y   gt  typeof DescriptionAttribute     y GetType              Select x   gt    DescriptionAttribute x GetCustomAttributes false  0   Description

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In addition to AdamCrawford response  I ve further created a more specialized extension methods that feed of it to get the description   public static string GetAttributeDescription this Enum enumValue        var attribute   enumValue GetAttributeOfType lt DescriptionAttribute gt         return attribute    null   String Empty   attribute Description       hence  to get the description  you could either use the original extension method as   string desc   myEnumVariable GetAttributeOfType lt DescriptionAttribute gt    Description   or you could simply call the the extension method here as    string desc   myEnumVariable GetAttributeDescription      Which should hopefully make your code a bit more readable

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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                      Now it will produce error in this case 1  Equals   public static string GetDisplayName this Enum enumValue                var enumMember   enumValue GetType   GetMember enumValue ToString    First            return enumMember GetCustomAttribute lt DisplayAttribute gt       null   enumMember GetCustomAttribute lt DisplayAttribute gt    Name   enumMember Name          so if it is same return enum name rather than display name because      enumMember GetCustomAttribute   gets null if displayname and enum name are same

[c#] Getting attributes of Enum's value

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