/// <summary>Cancela uma determinada requisição</sumary>
        public ObjResult Cancel(int request_id)
        {
            connection = db.GetCon();
            connection.Open();

            RequestDao dao    = new RequestDao(connection, null);
            ObjResult  result = new ObjResult();

            try
            {
                request_id = dao.Cancel(request_id);
                result.SetData(request_id);
                result.Success();
            }
            finally
            {
                connection.Close();
                db.Close();
            }

            return(result);
        }