所以我有这个

$master_item_id = array_map('intval', $request->master_item_id);
        $quantity = array_map('intval', $request->quantity);
        $price = MasterItem::whereIn('id', $master_item_id)->get('price');

        foreach ($master_item_id as $key => $no) {
            $input['price'] = $price[$key]['price'];
            $input['quantity'] = $quantity[$key];
            $subtotal[] = $input['price'] * $input['quantity'];
        }

        $total_price = array_sum($subtotal);

        // Update transaction
        $transaction = Transaction::find($id);
        $transaction->total_price = $total_price;
        $transaction->last_edited_by = Auth::user()->name;
        $transaction->update();

        // Update transaction_item
        foreach ($master_item_id as $key => $no) {
            $transaction = Transaction::find($id);
            $transaction->transaction_item->transaction_id= $transaction->id;
            $transaction->transaction_item->master_item_id = $no;
            $transaction->transaction_item->quantity = $quantity[$key];
            $transaction->transaction_item->price = $price[$key]['price'];
            $transaction->transaction_item->update();
        }

我的模型
x一个一个一个一个x一个一个二个一个x一个一个三个一个
我的表结构

transaction: id(pk), total_price
transaction_item: id(pk), transaction_id(fk), master_item_id(fk), quantity, price
master_item: id(pk), item_name, price

当我尝试更新它弹出错误

Method Illuminate\Database\Eloquent\Collection::update does not exist.

错误突出显示了我的代码中的这一行

$transaction->transaction_item->update();

我如何编辑/更新多行数据？我在模型中的关系是否正确？谢谢!