public async Task <ActionResult <Category> > PostCategory(Category category) { if (category.Id != 0) { return(null); } string c = _context.PostCategory(category); if (c == "Category added successfully.") { _context.db_categories.Add(category); await _context.SaveChangesAsync(); return(CreatedAtAction("GetCategory", new { id = category.Id }, category)); } else { return(null); } }