SQLAlchemy 1.4 -> 2.0 Update

[teald]

Info

This issue tracks update progress, tasks, and information w.r.t. updating SQLAlchemy. The TODO section has a checklist for specific items that are completed or need to be done.

Branch: sqlalchemy_update

TODO

• Get tests running locally
• Migration Guide steps with code_tests
  • Activate & Resolve RemovedIn20Warnings
    • (🤖) sqlalchemy.ext.declarative.declarative_base -> sqlalchemy.orm.declarative_base (imports, mostly)
    • (🤖) get from session queries is unsupported: session.query(TABLE).get(KEY) -> session.get(TABLE, KEY), for example
    • (🔧) sqlalchemy.orm.relation -> sqlalchemy.orm.relationship
  • Activate & resolve issues with adding future=True to instances of Engine
    • (🤖) Find all instances of engine instantiation.
      • It looks like there's just one in fits_storage.db.__init__.py that's saved. This doesn't cause any issues in the code tests with the future=True flag added to create_engine there.
      • More general search by eye (find fits* -type f -name "*.py" | xargs grep -ni -E "engine\W")
  • Use the future flag on Session
    • (🔧) Find all instances of Session without future=True
      • (🔧) This manifests in sessionmaker(..., future=True, ...).
    • Check for problems with Session instances and how they are invoked.
      • None, it seems like this is mostly enabling features on top of the pre-2.0 ones, beyond some esoteric cases not encountered in FitsStorage2.
  • Add __allow_unmapped__ to explicitly typed ORM models
    • This had no issues.
  • Test with SQLAlchemy 2

Misc. TODO

• Add check for sqlalchemy version to automated script.

TODO Key

(🤖) - step automated for updates to the codebase
(🔧) - could be automated
(✍️) - in progress
(💥) - major problem

Notes

• Both and environment variable SQLALCHEMY_WARN_20 and the -W always::DeprecationWarning test3.py flag must be used to actually coax out the RemovedIn20Warnings. Unfortunately, the errors will not always correctly report unless both of these are set.