Adopt new context tracking sysyem

[guillermohs9]

Hi! I'm using this extension is a couple of Flask projects and a Quart one. When trying to migrate the Quart app to it's latest version, the extension stopped working with the flask_patch:

ImportError: cannot import name '_app_ctx_stack' from 'quart.flask_patch'

According to what I understand from this answer, _app_ctx_stack will soon no longer be available in Flask either.

According to Quart's changelog:

Remove usage of LocalStacks, using ContextVars more directly. This
should improve performance, but introduces backwards
incompatibility. _*_ctx_stack globals are removed, use *_context
instead. Extensions should store on g as appropriate.

Are there any plans on making the appropiate changes on this extension to support this newer Quart release and Flask's future releases that drop _app_ctx_stack?

Thanks

[kasium]

Accessing the context will now also lead to a deprecation warning

venv/lib/python3.7/site-packages/flask_sqlalchemy/__init__.py:14: in <module>
    from flask import _app_ctx_stack, abort, current_app, request
venv/lib/python3.7/site-packages/flask/__init__.py:56: in __getattr__
    stacklevel=2,
E   DeprecationWarning: '_app_ctx_stack' is deprecated and will be removed in Flask 2.3

Same applies to _request_ctx_stack

[davidism]

Fixed in #1087. Using db.session or db.engine now always requires an active Flask application context. The session is scoped to the current context, which ensures it is always cleaned up.

[pdjohntony]

Still doesn't seem to be working with Quart using the latest 3.0.0a2 version.

Traceback (most recent call last):
  File "c:\Code\proj\run.py", line 14, in <module>
    from flask_sqlalchemy import SQLAlchemy
  File "c:\Code\proj\env\lib\site-packages\flask_sqlalchemy\__init__.py", line 5, in <module>
    from .extension import SQLAlchemy
  File "c:\Code\proj\env\lib\site-packages\flask_sqlalchemy\extension.py", line 23, in <module>
    from .session import _app_ctx_id
  File "c:\Code\proj\env\lib\site-packages\flask_sqlalchemy\session.py", line 8, in <module>
    from flask.globals import app_ctx
ImportError: cannot import name 'app_ctx' from 'quart.flask_patch.globals' (c:\Code\proj\env\lib\site-packages\quart\flask_patch\globals.py)

[davidism]

Check the traceback, that's an issue with Quart (which I think is also fixed). Regardless, this is Flask-SQLAlchemy, we don't provide direct compatibility with Quart.

[pdjohntony]

This is also the latest version of Quart so its not fixed quite yet, and looks like it might not get fixed at all based on this comment pallets/quart#156 (comment) about flask-patching possibly being removed from Quart in the future.

Regardless, I understand this is a Quart issue and not a Flask-SQLAlchemy issue. I just wanted to share that this isn't working with Quart currently. Thanks.

[guillermohs9]

Chech the traceback, that's an issue with Quart (which I think is also fixed). Regardless, this is Flask-SQLAlchemy, we don't provide direct compatibility with Quart.

Although I understand direct compatibility with Quart isn't provided, wouldn't importing app_ctx be incompatible when Flask 2.3 is out?

[davidism]

The opposite, app_ctx is what's compatible with Flask >= 2.2. Please open a new issue with the appropriate project if you have further issues.

[pgjones]

Quart 0.18.3 should fix the app_ctx issue.