public IHttpActionResult PostActivityVote(ActivityVote activityVote)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            var context = new TripServiceAppContext();

            lock (lockObj)
            {
                ActivityVote vote = context.ActivityVotes.Where(r => r.TripActivityId == activityVote.TripActivityId && r.TripUserId == activityVote.TripUserId).FirstOrDefault();

                // user had already voted. update their vote
                if (vote != null)
                {
                    vote.Vote = activityVote.Vote;

                    return PutActivityVote(vote.Id, vote); ;
                }

                else
                {
                    context.ActivityVotes.Add(activityVote);
                    context.SaveChanges();

                    return CreatedAtRoute("DefaultApi", new { id = activityVote.Id }, activityVote);
                }
            }
        }
        public IHttpActionResult PutActivityVote(int id, ActivityVote activityVote)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

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

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

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

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