What is the best way to store user ids in a Django model?

Question

Django

Hello. On the site there is a need to fasten the rating of users who wrote the article. I did the rating, but it is necessary to implement a mechanism for checking "Like Users", i.e. Each registered user can like only once. I created a CharField field for the user and in it I store the id of the user who likes it. Rating = likes - dislikes.
User model

class Author(models.Model):
    user = models.OneToOneField(User, on_delete=models.CASCADE)
    avatar = models.ImageField(upload_to='avatar', blank=True)
    like = models.IntegerField(default=0, verbose_name='Нравится')
    dislike = models.IntegerField(default=0, verbose_name='Не нравится')
    user_like_list = models.CharField(max_length=300, blank=True, verbose_name='id лайкнувших пользователей')

Like function

def add_like(request, slug):
    article = Article.objects.get(slug=slug)
    try:
        article = get_object_or_404(Article, slug=slug)
        article.author.user_like_list = article.author.user_like_list + str(request.user.id) + ','
        user_list = []
        for item in article.author.user_like_list:
            user_list.append(item)
        if request.user.id in user_list:
            return redirect('article', slug=slug)
        else:
            article.author.like += 1
            article.author.save()

How to implement it correctly and easier?