[Python] SQLAlchemy circular one-to-one relationship

I am trying to make a circular one-to-one relationship (not sure what the correct term is) with SQLAlchemy that looks the following:

class Parent(Base):
__tablename__ = 'parents'
id = db.Column(Integer, primary_key=True)
child_id = db.Column(db.Integer,db.ForeignKey("children.id", use_alter=True))
child = db.relationship("Child",
uselist=False,
foreign_keys=[child_id],
post_update=True)

class Child(Base):
__tablename__ = 'children'
id = db.Column(db.Integer, primary_key=True)
parent_id = db.Column(db.Integer, db.ForeignKey("parents.id"))
user = db.relationship("Parent",
uselist=False,
foreign_keys=[parent_id])


Everything works as expected until I try to db.drop_all() and I get an error that the sqlalchemy.sql.schema.ForeignKeyConstraint name is None. Am I doing something wrong when trying to make this circular one-to-one relationship? I would really like to be able to query just the single column to get the id of the other one, hence the circular reference.

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