public function search(Request $request, $category_id)
 {
     $term = $request->input('q');
     $items = App\Item::whereHas('categories', function ($q) use($category_id) {
         $q->where('id', '=', $category_id);
     })->where('name', 'like', '%' . $term . '%')->orderBy('name')->get();
     return response()->json($items);
 }