Click here to Skip to main content
Click here to Skip to main content

Mapping Text to Enum entries

, 6 Jun 2003
Rate this:
Please Sign up or sign in to vote.
Attaching a description to each entry in an enum.

Sample Image - EnumWithDescription.png

Introduction

While porting old C code to C#, I stumbled across lots of huge arrays which mapped constants to strings. While looking for the C# way of doing this, I discovered custom attributes and reflection.

How is it done?

Append a Description attribute to each enum entry:

private enum MyColors
{
   [Description("yuk!")]       LightGreen    = 0x012020,
   [Description("nice :-)")]   VeryDeepPink  = 0x123456,
   [Description("so what")]    InvisibleGray = 0x456730,
   [Description("no comment")] DeepestRed    = 0xfafafa,
   [Description("I give up")]  PitchBlack    = 0xffffff,
}

To access the description from code, the following function is called:

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

Without the following using declaration, the code will not compile.

using System.ComponentModel;        
using System.Reflection;

Benefits

Instead of having constants and huge arrays all over the code, the above solution keeps declarations and descriptions nicely together.

History

I've only found out by accident that the framework already provides a DescriptionAttribute class.

I built the first version with my own custom attribute and got conflicts when I started using the ComponentModel namespace.

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

Share

About the Author

Reto Ravasio

Switzerland Switzerland
No Biography provided

Comments and Discussions

 
GeneralMy vote of 5 Pinmemberlendres3-Apr-12 8:14 
GeneralMy vote of 5 PinmemberDorofejev20-Dec-11 0:44 
QuestionHow to use with dataset / tableadapter PinmemberSaelen Kenny8-Nov-09 1:01 
QuestionQuery regarding description Tag in Enum PinmemberNITINKADAM24-Nov-08 6:14 
GeneralAwesome - thanks! Pinmember93522-Jun-07 6:48 
GeneralDifferent versions for speed improvements Pinmemberclementgatin12-Mar-07 12:37 
GeneralThanks again PinprotectorMarc Clifton15-Oct-06 4:39 
GeneralSolution for C / C++ PinmemberJimmyO5-May-05 10:56 
GeneralRe: Solution for C / C++ PinsitebuilderUwe Keim10-Apr-06 20:53 
Questionwhy??? Pinmemberkoo918-Jan-05 11:53 
AnswerRe: why??? PinmemberReto Ravasio19-Jan-05 9:36 
QuestionWhat about Flags? PinmemberSpliffy7322-Mar-04 5:22 
AnswerRe: What about Flags? PinmemberJSpens14-Aug-07 8:50 
AnswerRe: What about Flags? Pinmemberfrinkfree11-Nov-08 13:55 
GeneralAutoDoc PinsussDave Miller4-Feb-04 18:50 
GeneralI liked this PinmemberPalladino26-Aug-03 3:39 
QuestionWhat About using the System Enum Pinmembervbnetuk25-Jun-03 23:10 
AnswerRe: What About using the System Enum PinmemberReto Ravasio4-Jul-03 2:04 
GeneralRe: What About using the System Enum Pinmembervbnetuk6-Jul-03 22:05 
GeneralRe: What About using the System Enum PinmemberReto Ravasio7-Jul-03 5:47 
GeneralRe: What About using the System Enum Pinmemberdevaulr6-Nov-03 3:40 
Reto,
 
I think you need to embellish us with a more detailed look at enumerations with spaces. I understand what you are saying about invalid characters, but the example isn't quite clear on it. Especially if you have an XML enumeration that you would be using in a web service environment.
 
In a web service environment, if the service uses a string enumeration VS. compacts the names for the enumeration and lays on the XMLAttribute tag with the actual name for the value which contained spaces.
 
example:
 
///
[System.Xml.Serialization.XmlEnumAttribute("Accounts Receivable")]
AccountsReceivable,
 
If you then want to present the correct strings in a listbox you must first iterate through the enum and create a new string[] containing the display strings.
 
When the user selects an element, the string must be compressed again back to the no spaces version which matches the enum names so that the correct enum entry can be located. whew!!
 


 
Russ DeVaul
Software Pathologist
GeneralRe: What About using the System Enum Pinmemberdatavalue19-Oct-05 4:06 
AnswerRe: What About using the System Enum PinmemberConradC1-Feb-05 9:22 
GeneralMultilingual PinsitebuilderUwe Keim7-Jun-03 22:36 
GeneralRe: Multilingual PineditorHeath Stewart27-Oct-03 6:07 
GeneralRe: Multilingual PinsitebuilderUwe Keim7-Mar-05 20:28 
GeneralRe: Multilingual PinmemberCraig Fisher30-Oct-07 10:18 
GeneralThe descriptions will also show up in the property grid Pinmemberleppie7-Jun-03 11:07 
GeneralRe: The descriptions will also show up in the property grid PinmemberReto Ravasio8-Jun-03 0:34 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.

| Advertise | Privacy | Terms of Use | Mobile
Web01 | 2.8.141220.1 | Last Updated 7 Jun 2003
Article Copyright 2003 by Reto Ravasio
Everything else Copyright © CodeProject, 1999-2014
Layout: fixed | fluid