computedindex

public class CustomComputedField : IComputedIndexField
    {
        public object ComputeFieldValue(IIndexable indexable)
        {
            Item item = indexable as SitecoreIndexableItem;
            if (item == null)
            {
                return null;
            }

            var database = item.Database;
            if (database == null)
            {
                return false;
            }
            //TODO:Implement logic to get the field value of the droplink
            //FieldName+="_appendsomevalue" - if you want to use a custom index name
        }

        public string FieldName { get; set; }
        public string ReturnType { get; set; }
    }