cssd-back/app/Models/Input.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsTo;
use Illuminate\Database\Eloquent\Relations\HasMany;

class Input extends Model
{
    use HasFactory;

    public $fillable = [
        'name', 'type', 'size', 'test_type_id', 'parent_id', 'require_scanner'
    ];

    public function test_type(): BelongsTo
    {
        return $this->belongsTo(TestType::class);
    }

    public function parent(): BelongsTo
    {
        return $this->belongsTo(Input::class, 'parent_id');
    }

    public function children(): HasMany
    {
        return $this->hasMany(Input::class, 'parent_id');
    }

    public function options(): HasMany
    {
        return $this->hasMany(Option::class);
    }
}