SQLAlchemy Obtain Primary Key With Autoincrement Before Commit

Question

You don't need to commit, you just need to flush. Here's some sample code. After the call to flush you can access the primary key that was assigned. Note this is with SQLAlchemy v1.3.6 and Python 3.7.4.

from sqlalchemy import *
import sqlalchemy.ext.declarative

Base = sqlalchemy.ext.declarative.declarative_base()

class User(Base):
    __tablename__ = 'user'
    user_id = Column('user_id', Integer, primary_key=True)
    name = Column('name', String)

if __name__ == '__main__':
    import unittest
    from sqlalchemy.orm import *
    import datetime

    class Blah(unittest.TestCase):
        def setUp(self):
            self.engine = create_engine('sqlite:///:memory:', echo=True)
            self.sessionmaker = scoped_session(sessionmaker(bind=self.engine))
            Base.metadata.bind = self.engine
            Base.metadata.create_all()
            self.now = datetime.datetime.now()

        def test_pkid(self):
            user = User(name="Joe")
            session = self.sessionmaker()
            session.add(user)
            session.flush()
            print('user_id', user.user_id)
            session.commit()
            session.close()

    unittest.main()