/// <summary>
        ///  insere um membro do staff na base de dados, requer platoonid apesar de esse elemento não ser necessário
        ///  para ser corrigido eventualmente
        /// </summary>
        /// <param name="name"></param>
        /// <param name="email"></param>
        /// <param name="platoonId"></param>
        /// <returns></returns>
        public XElement InsertStaff(string name, string email, string platoonId)
        {
            XElement xElem = new XElement("isSaved");

            // validar parâmetros de entrada antes de os enfiar na base de dados
            if (!string.IsNullOrEmpty(name) && !string.IsNullOrEmpty(email) && !string.IsNullOrEmpty(platoonId))
            {
                Staff staff = new Staff { Name = name, Email = email, PlatoonId = Convert.ToInt32(platoonId) };
                db.Staff.Add(staff);
                db.SaveChanges();
                xElem.Value = "true";

            }
            else if (!string.IsNullOrEmpty(name) && !string.IsNullOrEmpty(email))
            {
                Staff staff = new Staff { Name = name, Email = email, PlatoonId = null};
                db.Staff.Add(staff);
                db.SaveChanges();
                xElem.Value = "true";
            }
            else
            {
                xElem.Value = "false";
            }
            return xElem;
        }
        /// <summary>
        ///  recupera o elemento do staff por id e devolve um xml
        /// </summary>
        /// <param name="staffId"></param>
        /// <returns></returns>
        public XElement GetStaffById(string staffId)
        {
            Staff staff = new Staff();

            int int_StaffId = Convert.ToInt32(staffId);

            if (!string.IsNullOrEmpty(staffId))
            {
                staff = db.Staff.Where(x => x.Id.Equals(int_StaffId)).FirstOrDefault();
            }
            else
            {
                return new XElement("");
            }

            XElement xElem = new XElement("staff",
                new XElement("id", staff.Id),
                new XElement("name", staff.Name),
                new XElement("email", staff.Email),
                new XElement("platoonid", staff.PlatoonId)
                );

            return xElem;
        }