WitShop/app/Models/Category.php

<?php

namespace App\Models;

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

class Category extends Model
{
    protected $fillable = ['parent_id','name','slug','description','image','sort_order','active','show_in_nav'];

    protected $casts = ['active' => 'boolean', 'show_in_nav' => 'boolean'];

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

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

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