public Categories Update(CategoriesViewModel categories)
        {
            if (categories == null)
            {
                throw new ArgumentNullException("categories");
            }
            Categories newCategory = new Categories();
            AutoMapper.Mapper.Map(categories, newCategory);
            this.db.Entry(newCategory).State = EntityState.Modified;
            this.db.SaveChanges();

            return newCategory;
        }
        public Categories Add(CategoriesViewModel categories)
        {
            if (categories == null)
            {
                throw new ArgumentNullException("categories");
            }
            Categories newCategory = new Categories();
            AutoMapper.Mapper.Map(categories, newCategory);
            this.db.Categories.Add(newCategory);
            this.db.SaveChanges();

            return newCategory;
        }