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Enum Display Extension

By , 30 Oct 2011
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Often, we use enums for some selection process (switch statements, etc.), but when we display them to the UI, we need it formatted differently (not camel hump or dash separated).

To start, attributes can be used to store the description, and should be stored in the DescriptionAttribute:

public enum EmployeeType
{
   [DescriptionAttribute("The Big Boss Man")]
   Boss,
 
   [DescriptionAttribute("Boss's lacky")]
   AdministrativeAssistant,
   
   Janitor,
 
   [DescriptionAttribute("Everyone Else")]
   StandardEmployee
}

Here, we have defined a simple enum called EmployeeType and added a description attribute to the ones we want to be displayed differently.

Now the interesting part. In case you are unfamiliar with Extensions, here is a link to the MSDN[^].

public static string DisplayString(this Enum value)
{
    //Using reflection to get the field info
    FieldInfo info = value.GetType().GetField(value.ToString());
 
    //Get the Description Attributes
    DescriptionAttribute[] attributes = (DescriptionAttribute[])info.GetCustomAttributes(typeof(DescriptionAttribute), false);
    
    //Only capture the description attribute if it is a concrete result (i.e. 1 entry)
    if (attributes.Length == 1)
    {
        return attributes[0].Description;
    }
    else //Use the value for display if not concrete result
    {
        return value.ToString();
    }
}

This extension to Enum can then be used like this:

EmployeeType emp = EmplyeeType.Boss;
...
string display = emp.DisplayString();//Retrieves "The Big Boss Man"
string janDisplay = EmployeeType.Janitor.DisplayString(); //retrieves "Janitor"

In addition, if you have the description, you can easily extend the string as well to get back to the actual enum value.

   
public static object EnumValueOf<t>(this string descriptionOrValue)
{
   //Get all possible values of this enum type
   Array tValues = Enum.GetValues(typeof(T));
 
   //Cycle through all values searching for a match (description or value)
   foreach (Enum val in tValues)
   {
       if (val.DisplayString().Equals(descriptionOrValue) || val.ToString().Equals(descriptionOrValue))
       {
          return val;
       }
    }
 
    throw new ArgumentException(string.Format("The string value is not of type {0}.", typeof(T).ToString()));
}</t>
 
Usage:
string display = "The Big Boss Man";
EmployeeType emp = (EmployeeType)display.EnumValueType<employeetype();>

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

Collin Jasnoch
Engineer
United States United States
No Biography provided

Comments and Discussions

 
GeneralMy vote of 5 PinmemberA.J.Wegierski14-Jul-12 19:13 
GeneralRe: My vote of 5 PinmemberCollin Jasnoch16-Jul-12 3:13 
GeneralMy vote of 5 Pinmemberjohannesnestler29-Jun-12 12:58 
GeneralReason for my vote of 5 Nice. Can't be used on .Net 2.0, but... PinmemberOshtri Deka29-Feb-12 21:05 
GeneralReason for my vote of 5 Reason? Is simply great! PinmemberFernandaUY21-Dec-11 14:01 
GeneralI'll ask up here, same question: If you use the DescriptionA... Pinmembergerm132-Nov-11 21:16 
GeneralReason for my vote of 4 nice little code PinmemberVijay Palaniappan1-Nov-11 11:23 
GeneralReason for my vote of 3 How about localized strings? PinmemberAdrian Cole25-Oct-11 16:20 
GeneralRe: A 3 for that? Ouch. I thought this was really kewl. Granted ... PinmemberCollin Jasnoch26-Oct-11 10:05 
GeneralGreat Enum Example Pinmemberraananv31-Oct-11 20:01 
GeneralRe: Great Enum Example PinmemberCollin Jasnoch1-Nov-11 4:06 

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