Laravel＆＃34;多对多的多态关系＆＃34;返回空数组

Question

Album.php

/**
 * Get all of the orders for the album.
 *
 * @return \Illuminate\Database\Eloquent\Relations\MorphToMany
 */
public function orders()
{
    return $this->morphToMany(Order::class, 'orderable');
}

book.php中

/**
 * Get all of the orders for the book.
 *
 * @return \Illuminate\Database\Eloquent\Relations\MorphToMany
 */
public function orders()
{
    return $this->morphToMany(Order::class, 'orderable');
}

Order.php

/**
 * Get all of the albums that are assigned this order.
 *
 * @return \Illuminate\Database\Eloquent\Relations\MorphToMany
 */
public function albums()
{
    return $this->morphedByMany(Album::class, 'orderable');
}

/**
 * Get all of the books that are assigned this order.
 *
 * @return \Illuminate\Database\Eloquent\Relations\MorphToMany
 */
public function books()
{
    return $this->morphedByMany(Book::class, 'orderable');
}

Orderables表：

• ORDER_ID
• orderable_id
• orderable_type

我已经在书籍，专辑，订单和商品中创建了一些记录。但是，当我试图从订单中获取书籍时，它会返回一个空数组。没有错误，只有空数组。你知道什么问题可以吗？