public Task<HttpResponseMessage> Post([FromBody]dynamic body)
        {
            var command = new CreateCategoryCommand(
                title: (string)body.title
            );

            var category = _service.Create(command);
            return CreateResponse(HttpStatusCode.Created, category);
        }
        public Category Create(CreateCategoryCommand command)
        {
            var category = new Category(command.Title);
            category.Register();
            _repository.Create(category);

            if (Commit())
                return category;

            return null;
        }