app/bundles/CoreBundle/Controller/AjaxLookupControllerTrait.php

<?php

declare(strict_types=1);

namespace Mautic\CoreBundle\Controller;

use Mautic\CoreBundle\Helper\InputHelper;
use Mautic\CoreBundle\Model\AjaxLookupModelInterface;
use Symfony\Component\HttpFoundation\Exception\BadRequestException;
use Symfony\Component\HttpFoundation\JsonResponse;
use Symfony\Component\HttpFoundation\Request;

trait AjaxLookupControllerTrait
{
    public function getLookupChoiceListAction(Request $request): JsonResponse
    {
        $dataArray = [];
        $modelName = InputHelper::clean($request->query->get('searchKey'));
        $search    = InputHelper::clean($request->query->get(str_replace('.', '_', $modelName)));
        $limit     = (int) $request->query->get('limit', '0');
        $start     = (int) $request->query->get('start', '0');

        if (!$modelName) {
            throw new BadRequestException('The searchKey parameter is required.');
        }

        if (!$search) {
            return new JsonResponse($dataArray);
        }

        $model = $this->getModel($modelName);

        if (!$model instanceof AjaxLookupModelInterface) {
            throw new BadRequestException("The model {$modelName} must implement the AjaxLookupModelInterface.");
        }

        $results = $model->getLookupResults($modelName, $search, $limit, $start);

        foreach ($results as $group => $result) {
            $option = [];
            if (is_array($result)) {
                if (!isset($result['value'])) {
                    // Grouped options
                    $option = [
                        'group' => true,
                        'text'  => $group,
                        'items' => $result,
                    ];

                    foreach ($result as $value => $label) {
                        if (is_array($label) && isset($label['label'])) {
                            $option['items'][$value]['text'] = $label['label'];
                        }
                    }
                } else {
                    if (isset($result['label'])) {
                        $option['text'] = $result['label'];
                    }

                    $option['value'] = $result['value'];
                }
            } else {
                $option[$group] = $result;
            }

            $dataArray[] = $option;
        }

        return new JsonResponse($dataArray);
    }

    /**
     * Get a model instance from the service container.
     *
     * @param string $modelNameKey
     *
     * @return AbstractCommonModel<object>
     */
    abstract protected function getModel($modelNameKey);

    /**
     * Get's the content of error page.
     *
     * @return Response
     */
    abstract public function renderException(\Exception $e);
}