public class SearchResult {
        private string objectId { get; set; }       // ИД объекта
 
        /// <summary>
        /// Идентификатор записи.
        /// </summary>
        [JsonIgnore] public string ID { get { return this.objectId; } }
    }

            var members = obj.GetType().GetProperties().ToDictionary(
                p => p.Name,
                p => { var v = p.GetValue(obj, null); return v == null ? null : v; }
            );
            foreach (var member in members) {
                string item =  member.Key + ": " + member.Value;
            }