[Answered ]-Is there a way to have dictinary-like field in Django model?

You should create an ForeignKey field between the user model and the voting model. To only allow a single vote, per user; per movie, you might want to create a unique key constraint, on the voting model, over the userid and the movieid.

The vote should then contain a relation to the movie and a rating. If a user withdraws his vote you remove it from database.

Using a dictionary will lead to problems for you as you will have multiple movies.

To increase the speed and performance counting the votes you might want to take a look at caching and simply cache the number of votes and update the number every time a vote was added/withdrawn by a user on the specific movie.

You can use: update_or_create() method with django ORM.
https://docs.djangoproject.com/en/1.10/ref/models/querysets/#update-or-create

If the database you are using is Postgres, then you can make use of JSONField

Have you checked django-star-ratings, Star ratings for your Django models with a single template tag.