What's the alternative to create_scoped_session in versions 3+ to create a session for the read replica?

[andrii-korotkov-verkada]

Hey. There's a session created for read replica using SQLAlchemy object's create_scoped_session with options={"expire_on_commit": False, "bind": database.get_engine(bind="replica")}. But the method was renamed and marked private in v3. What's the alternative to this? Here's a potentially related question #1374.

[davidism]

You can use the private attribute, with the understanding you're using something private that might change. Write tests so you catch if something does change in that case.

Creating a bunch of scoped sessions is probably not doing what you intended it to. It requires you actually accessing the session again in a new scope in order to clean up the old scope. Flask-SQLAlchemy manages this by calling session.remove() at request teardown. So you probably just want to create instances of flask_sqlalchemy.session.Session(db) instead.

You might want to look at Flask-SQLAlchemy-Lite as an alternative if you want to manage the session yourself anyway: https://flask-sqlalchemy-lite.readthedocs.io/en/latest/session/