/// <summary>
        /// returns list of all customers
        /// </summary>
        /// <returns></returns>
        public IList <ICustomerDTO> GetAllCustomers()
        {
            var config = new MapperConfiguration(cfg => cfg.CreateMap <ICustomer, ICustomerDTO>());
            var mapper = new Mapper(config);

            return(mapper.Map <List <ICustomerDTO> >(_db.GetCustomers()));
        }