public IHttpActionResult PostCity(City city)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            db.Cities.Add(city);

            try
            {
                db.SaveChanges();
            }
            catch (DbUpdateException)
            {
                if (CityExists(city.CityId_PK))
                {
                    return Conflict();
                }
                else
                {
                    throw;
                }
            }

            return CreatedAtRoute("DefaultApi", new { id = city.CityId_PK }, city);
        }
        // PUT api/CityAPI/5
        public IHttpActionResult PutCity(Guid id, City city)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            if (id != city.CityId_PK)
            {
                return BadRequest();
            }

            db.Entry(city).State = EntityState.Modified;

            try
            {
                db.SaveChanges();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!CityExists(id))
                {
                    return NotFound();
                }
                else
                {
                    throw;
                }
            }

            return StatusCode(HttpStatusCode.NoContent);
        }