Fix TypeError when reading timestamps via the driver's time_zone option

[florinutz]

The CrateDB driver (crate-python) can return timezone-aware datetime objects when its time_zone argument is configured. But using that option through the SQLAlchemy dialect crashed:

TypeError: strptime() argument 1 must be str, not datetime.datetime

Root cause

Reading a TIMESTAMP involves two layers. Normally the driver passes the raw epoch-millis value through and the dialect's DateTime.result_processor converts it to a datetime. When time_zone is set, the driver converts the value to a datetime first — so the dialect's processor received an already-converted datetime, tried to convert it (TypeError, caught), then fell through to strptime(value, ...) (TypeError, uncaught) → crash.

The processor assumed it was always first in line to do the conversion.

Fix

Make DateTime.result_processor idempotent: if the value is already a datetime (the driver converted it), pass it through unchanged.

if isinstance(value, datetime):
    return value

Closes #92 (was actually already done)

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on this repository. Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: d050c811-f77b-466c-a92d-83f8b02be2b5

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/datetime-idempotency

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[bgunebakan]

Thank you!

[amotl]

Reading a TIMESTAMP involves two layers. [...] Make DateTime.result_processor idempotent.

Excellent, thank you!