Binding an Enum to a List Control

Posted on December 4th, 2003

At work we use a fair amount of enumerators in our code to define the values for lookup tables in the database. This a great way to implement these values because it avoids magic numbers and is easier to read and to maintain. But as much as I like working with enumerators, I’ve always struggled with the fact that I couldn’t bind them to list controls in the UI. Essentially there are 2 options you have to accomplish this:
1) Hard code the enumerated values into the list control - this is obviously a bad idea.
2) Just get the values from the DB since they are synchronized anyway - This idea actually works pretty well especially if you have a good caching mechanism in place
Even though #2 isn’t a terrible solution, it still bothered me to have to go to the DB to get values I already have defined in code. So I took a little time yesterday and wrote a method to populate a list control with the values of an enumerated type. Here is the code, note the last parameter will break apart your enumerator for better display - eg. ThisIsAnEnum will become This Is An Enum in the list control:

    /// 

    /// Populates a list based on the values of an enumerator
    /// 
    /// Web control to populate
    /// An enumeration type
    /// If true will break enum value with spaces on case change
    public static void PopListFromEnum(ListControl list, System.Type enumType, bool spaceOnCase)
    {
        list.Items.Clear();
        Array vals = Enum.GetValues( enumType);
        for(int i = 0; i < vals.Length; i++)
        {
            string val = vals.GetValue(i).ToString();
            string text = val;
            if (spaceOnCase)
            {
                char[] cars = text.ToCharArray( 1, text.Length - 1 );
                int offset = 1; // count the fact we are startng at position 1 to start with
                for(int x = 0; x < cars.Length; x++)
                {
                    if (Char.IsUpper( cars[x] ))
                    {
                        text = text.Insert( x + offset, " " );
                        offset += 1;
                    }
                }
            }
            list.Items.Add( new ListItem( text, val ) );
        }
    }
 Once you have the list populated to assign the selected value back out you can do something like this: 

object.SomeEnum = (SomeEnum)Enum.Parse( typeof(SomeEnum), ListControl.SelectedValue );

Filed under .NET |

2 Responses to “Binding an Enum to a List Control”

1. Anonymous Says:
   January 23rd, 2004 at 10:39 pm

   Separating the enum name with spaces is clever for a native application, but what’s your solution for localizing enums?

2. Anonymous Says:
   February 2nd, 2004 at 6:17 pm

   Yeah, thats a good point Derek. Fortunately for me we dont have to worry about the localization bit. It would definately add some complexity to this solution.

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