In the Flask project, how to use MySQL and MongoDB, Sqlalchemy and MongoEngine at the same time?

from mongoengine import *
 import datetime
 
 class Page(Document):
 title = StringField(max_length=200, required=True)
 date_modified = ateTimeField(default=datetime.datetime.now)
 author = xxxx?  ?  ?  ?  [How does this relate to User?  ?  Manual?  】
 
 
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 from sqlalchemy import Column, Integer, String
 class User(Base):
 __tablename__ = 'users'
 id = Column(Integer, primary_key=True)
 name = Column(String)
 fullname = Column(String)
 password = Column(String)