public override IDictionary<string, object> Serialize(object obj, JavaScriptSerializer serializer) { DatePicker timelineBookmark = obj as DatePicker; if (timelineBookmark != null) { Dictionary<string, object> dictionary = new Dictionary<string, object>(); dictionary.Add("Start", timelineBookmark.StartDate.ToString("yyyy/MM/dd")); dictionary.Add("End", timelineBookmark.EndDate.ToString("yyyy/MM/dd")); return dictionary; } return null; }