How do relationships work on the mongoengine?

Question

I'm new in mongoengine and I'm trying to relate two documments.

class Actor(Document):
    name = StringField(required=True, unique=True)
    movies = ListField()

class Movie(Document):
    title = StringField(required=True, unique=True)
    release_date = DateField()
    director = StringField()
    cast = ListField(ReferenceField(Actor))

I'd like to list the actors and have the movies appear. Or list the movies and the actors would appear related.

In my mind, I think of something like this:

class Actor(Resource):
    def get_actors(self) -> Response:
        for actor in Actor.objects.all():
            movies = Movie.objects(actors=actor)
            [...]
        return Response(planets, mimetype='application/json', status=200)

Is this a valid path, or is my head in Postgres and Mongo different? Any ideas?

Answer 1

In mongoengine, if you use ReferenceField, this will auto queryset to Actor. So you only need create a function to return a dict value.

class Actor(Document):
    name = StringField(required=True, unique=True)
    movies = ListField()

    def as_dict(self):
        return {
            "id": str(self.pk),
            "name": self.name,
            "movies": self.movies
        }

class Movie(Document):
    title = StringField(required=True, unique=True)
    release_date = DateField()
    director = StringField()
    cast = ListField(ReferenceField(Actor))
    
    def as_dict(self):
        return {
            "id": str(self.pk),
            "title": self.title,
            "release_date": self.release_date.isoformat(),
            "director": self.director,
            "cast": [i_cast.as_dict() for i_cast in self.cast]
        }

In API, you only call ac_dict after query to return data

def get_actors(self) -> Response:
    actors = Actor.objects.all()
    return Response([actor.as_dict() for actor in actors], mimetype='application/json', status=200)