openclassify/Modules/Category/Models/Category.php

<?php
namespace Modules\Category\Models;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\HasMany;
use Illuminate\Database\Eloquent\Relations\BelongsTo;
use Spatie\Activitylog\LogOptions;
use Spatie\Activitylog\Traits\LogsActivity;

class Category extends Model
{
    use LogsActivity;

    protected $fillable = ['name', 'slug', 'description', 'icon', 'parent_id', 'level', 'sort_order', 'is_active'];
    protected $casts = ['is_active' => 'boolean'];

    public function getActivitylogOptions(): LogOptions
    {
        return LogOptions::defaults()
            ->logFillable()
            ->logOnlyDirty()
            ->dontSubmitEmptyLogs();
    }

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

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

    public function listings(): HasMany
    {
        return $this->hasMany(\Modules\Listing\Models\Listing::class);
    }
}