App\Http\Controllers\ProductsGroupController::store PHP Method

    public function store(Request $request)
    {
        $id = $request->get('id');
        $group = $request->get('group');
        $group_id = false;
        $product = Product::select('id', 'products_group', 'price')->with(['group' => function ($query) {
            $query->select('id', 'products_group');
        }])->find($id);
        //is necesary re make the actual group before add to new one because is the principal product of the last one
        if ($product->products_group == $id && count($product->group) > 1 && $product->products_group != $group) {
            $newPrincipal = Product::select('id')->where('products_group', $id)->where('id', '<>', $id)->first();
            $group_id = $newPrincipal->id;
            Product::where('products_group', $id)->update(['products_group' => $group_id]);
        } elseif ($product->products_group == $group) {
            return;
        }
        if (!$group_id) {
            $group = Product::select('id', 'products_group')->find($group);
            if (is_null($group->products_group)) {
                $group->products_group = $group->id;
                $group->save();
            }
            $group_id = $group->products_group;
        }
        $product->products_group = $group_id;
        $product->save();
        return json_encode(['price' => \Utility::showPrice($product->price), 'label_delete' => trans('product.delete_from_group'), 'message' => trans('product.product_successfully_grouped')]);
    }