private string[] BuildFindElements(IEnumerable <string> findFields) { if (findFields == null) { return(null); } var list = new List <string>(); var entity = EntityExtensions.Create <TEntity>(); var properties = entity.GetPropertys(); foreach (var property in properties) { if (findFields != null && !findFields.Contains(property.Name)) { continue; } var elmentName = entity.BsonElementName(property.Name); if (elmentName == null) { continue; } list.Add(elmentName); } return(list.ToArray()); }