Laravel.io
public function getAlgoliaRecord()
    {
        $extra_data = [];
        $extra_data['car_model'] = array_map(
            function ($data) {
                return $data['name'];
            },
            $this->car_model->toArray()
        );

        $extra_data['car_serie'] = array_map(
            function ($data) {
                return $data['name'];
            },
            $this->car_serie->toArray()
        );

        $extra_data['car_mark'] = array_map(
            function ($data) {
                return $data['name'];
            },
            $this->car_model->car_mark->toArray()
        );

        $extra_data['car_mark_ru'] = array_map(
            function ($data) {
                return $data['name_ru'];
            },
            $this->car_model->car_mark->toArray()
        );

        $extra_data['car_generation'] = array_map(
            function ($data) {
                return $data['name'];
            },
            $this->car_serie->car_generation->toArray()
        );

        return array_merge($this->toArray(), $extra_data);
    }

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