Proper way to make changes to already created sqlite database with Pony ORM

Question

I am probably asking an obvious thing, but I could not find the answer. I am learning Pony ORM, and started with creating simple database from the documentation. I made a design of a simple database diagram and code https://editor.ponyorm.com/user/nidza11/Ponz# 

from pony.orm import *

db = Database()

class Person(db.Entity):
    id = PrimaryKey(int, auto=True)
    name = Required(str)
    age = Required(int)
    cars = Set('Car', cascade_delete=True)

class Car(db.Entity):
    id = PrimaryKey(int, auto=True)
    make = Required(str)
    model = Required(str)
    person = Required(Person)

db.bind("sqlite", "TestDB.sqlite", create_db = True)
db.generate_mapping(create_tables=True)

with db_session:
    p1 = Person(name="John", age=24)
    p2 = Person(name="Ive", age=26)
    p3 = Person(name="Olivia", age = 26)
    c1 = Car(make="Toyota", model = "Prius", person = p2)
    p3 = Car(make="Ford", model = "Explorer", person = p3)

After running the code, database was created and populated. I would like to make a name attribute in Person table unique. So I made a change in code name = Required(str, unique=True) After running the code again database was populated, but the name field is not set unique. Data was duplicated. According to DB browser name field was 'unique'. I expected an error. Such error will help me keep entity and database synchronized.

Adding a new attribute only in Person table class, but not in database, will cause an error.

Is it possible to make a change only in one place inside the code, that will reflect in database as well?

If I have to make a same change on two places, how to do it nice and clean?

Answer 1

I've just asked on the Pony ORM 'Telegram' group and this is the transaction that occurred there.