@Override
    @Transactional(readOnly = true)
    public List<TopicModel> getTopicsByTitle(String title){
        ModelMapper modelMapper = new ModelMapper();
        List<TopicModel> topics = new ArrayList<>();
        for(TopicEntity t : topicRepository.findByTitle(title))
            topics.add(modelMapper.map(t, TopicModel.class));
        return topics;
    }