How to get Reference Field from MongoDB using Flas\MongEngine?

Question

MongoDB

Hello!
There is a problem:
With the help of MongoEngine, I created a "scheme" of documents:

class Users(Document):
    login = fields.StringField(unique=True, max_length=25, primary_key=True, required=True)
    books = fields.ListField(fields.ReferenceField('Books'), default=["No favorites"])

and

class Books(Document):
    title = fields.StringField(required=True)
    author = fields.StringField()

Now, using Flask, I've done the following:

@app.route('/users/<id>', methods=['GET'])
def edit_user(id):
    user = Users.objects(login=id)
    books = [Books.objects(id__in=user[0].books)]
    return user.to_json(), books.to_json()

All is well, as long as I try to "get" only user. When I try to retrieve the books (ReferenceField) object, I get the following error:

ValidationError: Books object is not a valid ObjectId

I want all objects with all the attributes referenced by the books field in the Users object.
How to me to draw out objects which lie in ReferenceField?
How to make a request?

Answer 1

Um, I’m not boom-boom in Python, especially in MongoEngine, but by analogy with other systems, user[0].books will return your books to you by independently executing the request that you are trying to execute by id manually.

Answer 2

Judging by the documentation, you need to do:
and the books field will be filled with objects...