// PUT api/Posts/5
        public HttpResponseMessage PutPost(int id, Post post)
        {
            if (!ModelState.IsValid)
            {
                return Request.CreateErrorResponse(HttpStatusCode.BadRequest, ModelState);
            }

            if (id != post.Id)
            {
                return Request.CreateResponse(HttpStatusCode.BadRequest);
            }

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

            try
            {
                db.SaveChanges();
            }
            catch (DbUpdateConcurrencyException ex)
            {
                return Request.CreateErrorResponse(HttpStatusCode.NotFound, ex);
            }

            return Request.CreateResponse(HttpStatusCode.OK);
        }
        public HttpResponseMessage PostPost(PostCreateModel model)
        {
            var post = new Post()
                {
                    Title = model.Title,
                    PostContent = model.PostContent,
                    PostDate = model.PostDate,
                };

                var categories = db.Categories.ToList();
                var categoryNames = categories.Select(c => c.Name).ToList();
                for (int i = 0; i < categoryNames.Count; i++)
                {
                    if (model.Categories.Contains(categoryNames[i]))
                    {
                        post.Categories.Add(categories[i]);
                        model.Categories.Remove(categoryNames[i]);
                    }
                }

                foreach (var cat in model.Categories)
                {
                    var category = new Category()
                    {
                        Name = cat
                    };

                    post.Categories.Add(category);
                }

                db.Posts.Add(post);
                db.SaveChanges();
                model.Id = post.Id;
                HttpResponseMessage response = Request.CreateResponse(HttpStatusCode.Created, model);
                response.Headers.Location = new Uri(Url.Link("DefaultApi", new { id = post.Id }));
                return response;
        }