invoiceninja/app/Models/Credit.php

<?php
/**
 * Invoice Ninja (https://invoiceninja.com)
 *
 * @link https://github.com/invoiceninja/invoiceninja source repository
 *
 * @copyright Copyright (c) 2019. Invoice Ninja LLC (https://invoiceninja.com)
 *
 * @license https://opensource.org/licenses/AAL
 */

namespace App\Models;

use App\Models\Filterable;
use App\Utils\Traits\MakesDates;
use App\Utils\Traits\MakesHash;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\SoftDeletes;

class Credit extends BaseModel
{
    use MakesHash;
    use Filterable;
    use MakesDates;
    use SoftDeletes;
    
    
    public function assigned_user()
    {
        return $this->belongsTo(User::class, 'assigned_user_id', 'id');
    }

    public function invoices()
    {
        return $this->morphToMany(Invoice::class, 'creditable');
    }
}