一对一关系烧瓶SQL炼金术

我必须在flask SQL alchemy中创建一个一对一的关系。我按照SO上的一些答案，发现我们必须定义 uselist=False 和 db.relationship 。但是当我在PGADMIN上看到ERD的时候，我看到的是一对多的关系。我的代码如下。

class Vehicle(db.Model):
    __tablename__ = "vehicles"
    id = db.Column(
        db.String,
        primary_key=True,
    type = db.Column(
        db.String,
        nullable=False,
    suspicious = db.Column(
        db.Boolean,
        nullable=False,
    registered_user = db.relationship("Registered", backref="vehicles", uselist=False)
    day_user = db.relationship("Visitor", backref="vehicles", uselist=False)
    def __init__(self, type, suspicious):
        self.type = type
        self.suspicious = suspicious
    def __repr__(self):
        return "Vehicle(type='{}', suspicious={})".format(self.type, self.suspicious)
    def serialize(self):
        return {"id": self.id, "type": self.type, "suspicious": self.suspicious}
    @classmethod
    def from_json(cls, json):
        return cls(json["type"], json["suspicious"])
class Registered(db.Model):
    Registered User
    __tablename__ = "registered"
    regID = db.Column(db.String, primary_key=True)
    name = db.Column(db.String, nullable=False)
    cnic = db.Column(db.String, nullable=False)
    contactNo = db.Column(db.String, nullable=False)
    gender = db.Column(db.String, nullable=False)
    DOR = db.Column(db.DateTime, nullable=False)
    DOE = db.Column(db.DateTime, nullable=False)
    vehicle_id = db.Column(db.String, db.ForeignKey("vehicles.id"), unique=True)
    def __init__(self, name, cnic, contactNo, gender, DOR, DOE, vehicle_id):
        self.name = name
        self.cnic = cnic
        self.contactNo = contactNo
        self.gender = gender
        self.DOR = DOR
        self.DOE = DOE
        self.vehicle_id = vehicle_id
    def __repr__(self):
        return "Registered(name='{}', cnic={},contactNo={},gender={},DOR={},DOE={})".format(
            self.name,
            self.cnic,
            self.contactNo,
            self.gender,
            self.DOR,
            self.DOE,
    def serialize(self):
        return {
            "regID": self.regID,
            "name": self.name,
            "cnic": self.cnic,
            "contactNo": self.contactNo,
            "gender": self.gender,
            "DOR": self.DOR,
            "DOE": self.DOE,
    @classmethod
    def from_json(cls, json, vehicle_id):
        return cls(
            json["name"],
            json["cnic"],
            json["contactNo"],
            json["gender"],
            json["DOR"],
            json["DOE"],
            vehicle_id,
class Visitor(db.Model):
    __tablename__ = "visitors"
    id = db.Column(db.Integer, primary_key=True, nullable=False, autoincrement=True)
    name = db.Column(db.String, nullable=False)
    cnic = db.Column(db.String, nullable=False)
    vehicle_id = db.Column(db.String, db.ForeignKey("vehicles.id"), unique=True)
    def __init__(self, name, cnic, vehicle_id):
        self.name = name
        self.cnic = cnic
        self.vehicle_id = vehicle_id
    def __repr__(self):
        return "Visitor(name='{}', cnic={})".format(self.name, self.cnic)
    def serialize(self):
        return {
            "id": self.id,
            "name": self.name,
            "cnic": self.cnic,
if __name__ == "__main__":
    db.create_all()
    db.session.commit()