public IHttpActionResult DeleteCategoryModel(int id)
        {
            // Possible bug here....
            // Ne dozvoliti brisanje ako povezani racuni i ponude nisu istekli
            if (billService.GetBillsByCategoryAndNotExpired(id, DateTime.UtcNow).Count() != 0 ||
                offerService.GetOffersByCategoryAndNotExpired(id, DateTime.UtcNow).Count() != 0)
            {
                return(StatusCode(HttpStatusCode.Forbidden));
            }

            Category categoryModel = categoryService.DeleteCategory(id);

            if (categoryModel == null)
            {
                return(NotFound());
            }

            return(Ok(categoryModel));
        }