internship-playground/src-php/app/internship/bo/MainNews.php

<?php

namespace internship\bo;

use n2n\persistence\orm\attribute\DiscriminatorValue;

#[DiscriminatorValue('mainNews')]
class MainNews extends News {
	public string $intro;

	public function jsonSerialize(): mixed {
		$parentJSON = parent::jsonSerialize();
		$parentJSON['intro'] = $this->intro;
		return $parentJSON;
	}
}