Пример модели для SQLAlchemy в SQLite ограничение на ForeignKey по умолчанию не работает, в PG все норм.

gistfile1.txt

from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, ForeignKey
from sqlalchemy.orm import sessionmaker
from sqlalchemy_utils import database_exists, create_database

engine = create_engine('sqlite:///')
engine = create_engine('sqlite:///example_1_fk_check.db')

# engine = create_engine("postgres://postgres@localhost/mydb_3")
# if not database_exists(engine.url):
#     create_database(engine.url)


print(database_exists(engine.url))

Session = sessionmaker(bind=engine)
sess = Session()
Base = declarative_base()

class Users(Base):
	__tablename__ = 'mans'
	id = Column(Integer, primary_key=True)
	mail_id = Column(Integer, ForeignKey("address.id"))
	name = Column(String)
	age = Column(Integer)
	
class Address(Base):
	__tablename__ = 'address'
	id = Column(Integer, primary_key=True, unique=True)
	email = Column(String)



Base.metadata.create_all(engine)


user1 = Users(id=1, mail_id=1, name='Mike', age=21)
# user2 = Users(id=2, name='Jow', age=22)
# user3 = Users(id=3, name='David', age=23)

adr1 = Address(id=1, email='[email protected]')

sess.add(user1)

sess.add(adr1)

# sess.add(user2)
# sess.add(user3)


sess.commit()

x = sess.query(Users).filter(Users.id>0).first()
# print(type(x))
print(x.name)