alrahma_sunday_school_api/app/Models/ParentModel.php

<?php

namespace App\Models;

class ParentModel extends BaseModel
{
    protected $table = 'parents';

    // legacy model didn't specify timestamps
    public $timestamps = true;

    protected $fillable = ['secondparent_firstname', 'secondparent_lastname', 'secondparent_gender', 'secondparent_email', 'secondparent_phone', 'firstparent_id', 'secondparent_id', 'semester', 'school_year', 'created_at', 'updated_at'];

    protected $casts = [
        'firstparent_id' => 'integer',
    ];

    /* Optional relationship */
    public function firstParentUser()
    {
        return $this->belongsTo(User::class, 'firstparent_id');
    }
}