allo/app/Http/Controllers/Controller.php

<?php

namespace App\Http\Controllers;

use App\Model\Form;
use App\Model\WorkOrder;
use Illuminate\Foundation\Bus\DispatchesJobs;
use Illuminate\Routing\Controller as BaseController;
use Illuminate\Foundation\Validation\ValidatesRequests;
use Illuminate\Foundation\Auth\Access\AuthorizesRequests;

class Controller extends BaseController
{
    use AuthorizesRequests, DispatchesJobs, ValidatesRequests;

    public function getUntaggedWorkOrder()
    {

        $result = array();
        $untaggedform = Form::where('customer_category', null)->get();

        foreach ($untaggedform as $key => $a) {
            $work_order = WorkOrder::where('_id', $a->_id)->get();
            
            if(!empty($work_order)){
                dd($work_order);
                array_push($result, array(
                    'wo' => $work_order->wo,
                ));
            }
        }

        return json_encode($result);
    }
}