example-code/php-laravel/app/Models/Service.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
use App\Models\Order;
use App\Models\Supplier;

class Service extends Model
{
    use HasFactory;

	protected $fillable = [
		'name', 'type', 'site', 'available'
	];

	public function order() {
		return $this->hasMany(Order::class);
	}

	public function suppliers() {
		return $this->hasMany(Supplier::class);
	}

	public function primary() {
		return $this->belongsTo(Supplier::class, 'primary_supplier', 'id');
	}

}