如何获得 sqlalchemy 关系来更新 order_by？

Question

Database Model:

class Facility(db.Model):
    __tablename__ = "facility"
    id                  = db.Column(db.Integer, primary_key=True)
    name                = db.Column(db.String(80), nullable=False)    
    created_at          = db.Column(db.DateTime, default=datetime.now())
    updated_at          = db.Column(db.DateTime, nullable=True)

    contacts = relationship(
        "Contact",
        secondary="facility_contact",
        order_by="desc(Contact.created_at)"
    )

Api Endpoint with Flask-Restful:

class FacilityPersonnelEndpoint(Resource):
    def __init__(self):
        self.parser = reqparse.RequestParser()
        self.parser.add_argument("facility_id", type=str)
        self.parser.add_argument("order_by", type=str)
        self.parser.add_argument("group_by", type=str)
        super(FacilityPersonnelEndpoint, self).__init__()

    def get(self) -> dict:
        args = self.parser.parse_args()

        facility = Facility.get_id(args["facility_id"])
        if not facility:
            return { "error": "Facility Personnel not found." }, 404

        return facility.contacts, 200

I would like to be able to do something like the pseudo-code below in the endpoint, but I can't seem to find any documentation that makes this possible.

order = args["order_by"]
group = args["group_by"]
sort = "{0}(Contact.{1})".format(order_by, group_by)
Facility.contacts.order_by(sort)

or calling the relationship as a function in the model?

@classmethod
def get_ordered_contacts(cls, order_by, group_by):
    sort = "{0}(Contact.{1})".format(order_by, group_by)
    contacts = relationship(
        "Contact",
        secondary="facility_contact",
        order_by=sort
    )
    return contacts

Is it possible to set this up in the model somehow or do I need to use a query in the endpoint? Or do I just need to sort after I've pulled the records from the database?