Inserting new records with one-to-many relationship in sqlalchemy

You dont need to write a constructor, you can either treat the addresses property on a Person instance as a list:

a = Address(email="foo@bar.com")
p = Person(name="foo")
p.addresses.append(a)

Or you can pass a list of addresses to the Person constructor

a = Address(email="foo@bar.com")
p = Person(name="foo", addresses=[a])

In either case you can then access the addresses on your Person instance like so:

db.session.add(p)
db.session.add(a)
db.session.commit()
print(p.addresses.count()) # 1
print(p.addresses[0]) # <Address object at 0x10c098ed0>
print(p.addresses.filter_by(email="foo@bar.com").count()) # 1