utils_timezone fixer doesn't seem to consider `ast.ImportFrom` nodes.

[rsiemens]

Python Version

3.10.11

Django Version

4.2.21

Package Version

1.25.0

Description

Hi Adam 👋

When trying to apply the utils_timezone fixer to some files I noticed it failed to apply some fixes. Below is a simple set of code you can use to reproduce:

from django.utils import timezone
from datetime import datetime

print(datetime.now(tz=timezone.utc))

Running django-upgrade --target-version=5.2 --only=utils_timezone simple_reproduction.py will not apply any transforms. At a quick glance it seems like when building the ImportDetails the code isn't looking for ast.ImportFrom nodes when identifying the datetime_module.

Thanks for your work on this package!

[adamchainz]

Yes, this is true - the docs say:

Requires an existing import of the datetime module.

I left out trying to extend a from datetime import It would require swapping to from datetime import timezone, which would conflict with from django.utils import timezone. It could only be done if django.utils.timezone has been imported only for utc, which is rare IMO, as timezone.now() is a common use case.

Happy to accept a well-tested PR, though!

[rsiemens]

Sorry for missing out on that documentation piece 🤦.

What do you think about an approach like this instead of trying to swap stuff around it just inserts a datetime import (potentially aliased) like so:

• if there is no import datetime check, is there is a from datetime import ...?
  • yes: is it from datetime import datetime?
    • yes: insert an import datetime as <some_non_conflicting_alias>
    • no: insert an import datetime
  • no: insert an import datetime

If that seems sound to you I'll try and take some time to familiarize myself a bit more with this package and make a pass at a PR.

[adamchainz]

I think a simplified plan could work: if there's no existing datetime import, check if the name dt is used anywhere in the module. If not, go for adding import datetime as dt, and using dt.timezone.utc.