flask-sqlalchemy join all matches from association table

Question

I am doing a project in Flask, I have a difficulty with Flask-SQLAlchemy.

class Films(db.Model):
    """Main film table"""
    __tablename__ = 'films'
    film_id = db.Column(db.Integer, primary_key=True)
    film_name = db.Column(db.Text, unique=False, nullable=False, index=True)

class Genres(db.Model):
    """Table with genres"""
    __tablename__ = 'genres'
    genre_id = db.Column(db.Integer, primary_key=True)
    genre_name = db.Column(db.String(20), unique=True, nullable=False)
    gen_films = db.relationship(
        'Films', secondary=films_genres, lazy='subquery',
        backref=db.backref('gen_films', lazy='joined'))

# Association table for table films and table genres
films_genres = db.Table(
    'films_genres',
    db.Column('films_film_id', db.Integer, db.ForeignKey('films.film_id')),
    db.Column('genres_genre_id', db.Integer, db.ForeignKey('genres.genre_id')))

all_films = Films.query.select_from(Films).join(films_genres).join(Genres).filter(
      (films_genres.c.films_film_id == Films.film_id) & (films_genres.c.genres_genre_id == Genres.genre_id))\
    .add_columns(
            Films.film_name,
            Genres.genre_name
            ).paginate()

When I make a request, I get an output like this:

[(<Films 1>, 'The Shawshank Redemption', 'Action'), (<Films 1>, 'The Shawshank Redemption', 'Crime')] ...

How can I redo the query to get this kind of result?

[(<Films 1>, 'The Shawshank Redemption', ('Action', 'Crime')]

Or something similar so that the genre list is one line, in order to further transfer this to flask_restx -> Resource -> json