jucai/app/Models/PolicyCategory.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\SoftDeletes;
use Encore\Admin\Traits\ModelTree;
use Encore\Admin\Traits\AdminBuilder;


class PolicyCategory extends Model
{
    use SoftDeletes,AdminBuilder,ModelTree {
        ModelTree::boot as treeBoot;
    }
    protected $table = 'policy_category';
    protected $guarded = [];

    public function __construct(array $attributes = [])
    {
        parent::__construct($attributes);
        $this->setParentColumn('parent_id');
        $this->setOrderColumn('category_order');
        $this->setTitleColumn('categoryname');
    }


    public function children()
    {
        return $this->hasMany(PolicyCategory::class, 'parent_id')->orderBy('category_order','desc');
    }
    public static function category($str)
    {
        return array_column(PolicyCategory::where('parent_id', $str)->get(['id',"categoryname"])->toArray(), 'categoryname', 'id');
    }
    

    
}