Flask Sqlalchemy Sessions Out Of Sync

I have a Flask REST API, running with a gunicorn/nginx stack. There is global SQLAlchemy session set up once for each thread that the API runs on. I set up an endpoint /test/ for

Solution 1:

Please use flask-sqlalchemy if you're using flask, it takes care of the lifecycle of the session for you.

If you insist on doing it yourself, the correct pattern is to create a session for each request instead of having a global session. You should be doing

Session = scoped_session(session_factory, scopefunc=flask._app_ctx_stack.__ident_func__)
return Session

instead of

Session = scoped_session(session_factory)
return Session()

And do

session = Session()

every time you need a session. By virtue of the scoped_session and the scopefunc, this will return you a different session in each request, but the same session in the same request.

Solution 2:

Figured it out. What I did was to add a setup and teardown to the request in my app's __init__.py:

@app.before_request
def startup_session():
    db.session = db.connectSQLAlchemy()

@app.teardown_request
def shutdown_session(exception=None): 
    db.session.close()

still using the global session object in my db module:

db.py:

....
session = None
....

The scoped_session handles the different threads, I think...

Please advise if this is a terrible way to do this for some reason. =c)