Get Enum from Description attribute

Question

Possible Duplicate    Finding an enum value by its Description Attribute       I have a generic extension method which gets the Description attribute from an Enum   enum Animal        Description          NotSet   0        Description  Giant Panda        GiantPanda   1        Description  Lesser Spotted Anteater        LesserSpottedAnteater   2    public static string GetDescription this Enum value                    FieldInfo field   value GetType   GetField value ToString          DescriptionAttribute attribute               Attribute GetCustomAttribute field  typeof DescriptionAttribute                   as DescriptionAttribute       return attribute    null   value ToString     attribute Description      so I can do     string myAnimal   Animal GiantPanda GetDescription          Giant Panda    now  I m trying to work out the equivalent function in the other direction  something like     Animal a    Animal Enum GetValueFromDescription  Giant Panda   typeof Animal

User · Answer

rather than extension methods  just try a couple of static methods  public static class Utility       public static string GetDescriptionFromEnumValue Enum value                DescriptionAttribute attribute   value GetType                GetField value ToString                 GetCustomAttributes typeof  DescriptionAttribute   false               SingleOrDefault   as DescriptionAttribute          return attribute    null   value ToString     attribute Description             public static T GetEnumValueFromDescription lt T gt  string description                var type   typeof T           if   type IsEnum              throw new ArgumentException            FieldInfo   fields   type GetFields            var field   fields                          SelectMany f   gt  f GetCustomAttributes                              typeof DescriptionAttribute   false                                     f  a    gt  new   Field   f  Att   a                             Where a   gt    DescriptionAttribute a Att                               Description    description  SingleOrDefault            return field    null   default T     T field Field GetRawConstantValue              and use here  var result1   Utility GetDescriptionFromEnumValue      Animal GiantPanda   var result2   Utility GetEnumValueFromDescription lt Animal gt        Lesser Spotted Anteater

User · Answer

You need to iterate through all the enum values in Animal and return the value that matches the description you need

User · Answer

Should be pretty straightforward  its just the reverse of your previous method   public static int GetEnumFromDescription string description  Type enumType        foreach  var field in enumType GetFields                  DescriptionAttribute attribute               Attribute GetCustomAttribute field  typeof DescriptionAttribute  as DescriptionAttribute          if attribute    null              continue          if attribute Description    description                        return  int  field GetValue null                       return 0      Usage   Console WriteLine  Animal GetEnumFromDescription  Giant Panda  typeof Animal

User · Answer

public static class EnumEx       public static T GetValueFromDescription lt T gt  string description  where T   Enum               foreach var field in typeof T  GetFields                          if  Attribute GetCustomAttribute field              typeof DescriptionAttribute   is DescriptionAttribute attribute                                if  attribute Description    description                      return  T field GetValue null                             else                               if  field Name    description                      return  T field GetValue null                                    throw new ArgumentException  quot Not found  quot   nameof description               Or return default T            Usage  var panda   EnumEx GetValueFromDescription lt Animal gt   quot Giant Panda quot

User · Answer

The solution works good except if you have a Web Service   You would need to do the Following as the Description Attribute is not serializable    DataContract  public enum ControlSelectionType        EnumMember Value    Not Applicable        NotApplicable   1       EnumMember Value    Single Select Radio Buttons        SingleSelectRadioButtons   2       EnumMember Value    Completely Different Display Text        SingleSelectDropDownList   3     public static string GetDescriptionFromEnumValue Enum value            EnumMemberAttribute attribute   value GetType                GetField value ToString                 GetCustomAttributes typeof EnumMemberAttribute   false               SingleOrDefault   as EnumMemberAttribute          return attribute    null   value ToString     attribute Value

User · Answer

You can t extend Enum as it s a static class  You can only extend instances of a type  With this in mind  you re going to have to create a static method yourself to do this   the following should work when combined with your existing method GetDescription   public static class EnumHelper       public static T GetEnumFromString lt T gt  string value                if  Enum IsDefined typeof T   value                         return  T Enum Parse typeof T   value  true                     else                       string   enumNames   Enum GetNames typeof T                foreach  string enumName in enumNames                                  object e   Enum Parse typeof T   enumName                   if  value    GetDescription  Enum e                                         return  T e                                                    throw new ArgumentException  The value      value                   does not match a valid enum name or description               And the usage of it would be something like this   Animal giantPanda   EnumHelper GetEnumFromString lt Animal gt   Giant Panda

[c#] Get Enum from Description attribute

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