one to one mapping sqlalchemy

models.py

from flask_sqlalchemy import SQLAlchemy
from sqlalchemy.orm import validates
db = SQLAlchemy()


class User(db.Model):
    __tablename__ = "user"

    id = db.Column(db.Integer, primary_key=True)
    first_name = db.Column(db.Unicode)
    last_name = db.Column(db.Unicode)
    email = db.Column(db.Unicode, nullable=True, unique = True)
    phone = db.Column(db.Unicode, nullable=True, unique = True)
    profile_pic = db.Column(db.Text, default='')

    loyalty = relationship("Loyalty", uselist=False, back_populates="user")

    @validates('email')
    def validate_email(self, key, email):
        assert '@' in email
        return email


class Loyalty(db.Model):
    __tablename__ = "loyalty"

    id = db.Column(db.Integer, primary_key=True)
    card_number = db.Column(db.Integer)
    points = db.Column(db.Integer)
    balance = db.Column(db.Integer)
    group_id = db.Column(db.Integer)
    user_id = db.Column(db.Integer, db.ForeignKey('user.id'))
    user = relationship("Loyalty", back_populates="loyalty")


db.create_all()