// PUT api/Session/5
        public async Task<IHttpActionResult> PutSessionModel(int id, SessionModel sessionmodel)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            if (id != sessionmodel.Id)
            {
                return BadRequest();
            }

            _db.Entry(sessionmodel).State = EntityState.Modified;

            try
            {
                await _db.SaveChangesAsync();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!SessionModelExists(id))
                {
                    return NotFound();
                }
                else
                {
                    throw;
                }
            }

            return StatusCode(HttpStatusCode.NoContent);
        }
        public async Task<IHttpActionResult> PostSessionModel(SessionModel sessionmodel)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            _db.Sessions.Add(sessionmodel);
            await _db.SaveChangesAsync();

            return CreatedAtRoute("DefaultApi", new { id = sessionmodel.Id }, sessionmodel);
        }