Laravel Relationship between Three Models - mysql

Question

sold_items:
id order_id customer_id name
-- -------- ----------- ----
1 5 14 An object
orders:
id po_num
-- ------
... ...
5 123
customers:
id name
-- ----
... ...
14 John Doe
A SoldItem has an order_id and a customer_id.
I'm trying to define a hasOne relationship between an Order and its Customer through the SoldItem without having to insert a customer_id column in the Order model's table.
hasOneThrough seemed to be the solution but I couldn't figure out where to go from there, or is that even the answer?
<?php
namespace App;
use Illuminate\Database\Eloquent\Model;
class Order extends Model
{
public $timestamps = false;
protected $guarded = ['id'];
public function sold_items()
{
return $this->hasMany('App\SoldItem');
}
public function customer()
{
// return $this->hasOneThrough();
}
}

Answer 1

for Customer model
{
public function sold_items()
{
return $this->hasMany('App\SoldItem');
}
}
for Order model
{
public function sold_items()
{
return $this->hasOne('App\SoldItem');
}
}
for SoldItem model
{
public function customer()
{
return $this->belongsto('App\Cutomer');
}
public function order()
{
return $this->belongsto('App\Order');
}
}
I prefer working on their relationship first then and use with() function to get their values.
use App\Customer;
$customer = Customer::with('sold_items','sold_items.order')->get();

Answer 2

I ended up making the Customer an attribute of the Order through its sold_items with:
<?php
namespace App;
use Illuminate\Database\Eloquent\Model;
class Order extends Model
{
public $timestamps = false;
protected $guarded = ['id'];
public function sold_items()
{
return $this->hasMany('App\SoldItem');
}
public function getCustomerAttribute()
{
return $this->sold_items->first()->customer;
}
}