HasMany关系，从关系中的孩子找到孩子索引？

I'm currently trying to access the index of a child in a HasMany relationship in a Laravel project. I have an order with many orderItems, but I can't seem to find a way to access the index of the orderItem I am dealing with from its relationship with the parent Order.

So, basically I want to be able to do $orderItem->order->index() if possible, is there anything within Eloquent that can give me this?

Here's some code to show you how I have the relationships setup...

Order.php

/**
 * @return HasMany
 */
public function orderItems()
{
    return $this->hasMany(OrderItem::class)->orderBy('id', 'DESC');
}

OrderItem.php

/**
 * @return BelongsTo
 */
public function order()
{
    return $this->belongsTo(Order::class);
}

What I want to do...

OrderItem::find(1)->order->index()

or something like that.

Any help is greatly appreciated.

If I get you correctly, You are trying to get all OrderItem ids related to Order. Then You can use pluck() to get this-

$order = Order::find($orderId);
$ids = $order->orderItems()->pluck('id');

I apologise to everyone that I confused with the question, what I wanted was to get the index of the current OrderItem I am dealing with as if it had been loaded via a relationship call.

In the end, this is the code that worked for me...

$this->$order->orderItems->pluck('id')->search($this->id)

This then returned the correct index to me.