models.py

from app import db

class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    nick = db.Column(db.String(14), unique=True)
    user_phone = db.Column(db.String(20), unique=True)
    is_subbed = db.Column(db.Boolean, default=True)
    is_admin = db.Column(db.Boolean, default=False)
    did = db.relationship('DID', uselist=False, back_populates="user")

    def __init__(self, nick, user_phone, did):
        self.nick = nick
        self.user_phone = user_phone
        self.did = did


class DID(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    number = db.Column(db.String(20), unique=True)
    user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=True)
    user = db.relationship("User", back_populates="did")
     
    def __init__(self, number):
        self.number = number