fix: add robust date parsing in schedule_fn

[camillobucciarelli]

I implemented a way to solve the issue reported in #255.

[gemini-code-assist]

Summary of Changes

Hello @camillobucciarelli, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly improves the date parsing capabilities within the schedule_fn module by introducing a more flexible and resilient approach to handling various date string formats. It prioritizes parsing using datetime.fromisoformat for modern ISO 8601 compliance, includes specific handling for RFC3339 'Z' timezone designators, and provides robust fallback mechanisms to ensure reliable processing of scheduled times, addressing potential issues with strict date format requirements.

Highlights

• Enhanced Date Parsing: Implemented a more robust date parsing mechanism for schedule_time_str within the on_schedule_wrapped function to handle various formats.
• fromisoformat Support: Introduced datetime.fromisoformat for primary parsing, which natively supports fractional seconds and diverse timezone offsets in Python 3.7+.
• RFC3339 'Z' Normalization: Added logic to normalize RFC3339 'Z' timezone designators to '+00:00' for compatibility with fromisoformat.
• Robust Fallback Mechanism: Included a fallback to the original strptime method if fromisoformat fails, and a final fallback to utcnow() with logging if all parsing attempts are unsuccessful, ensuring a valid schedule_time.

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[gemini-code-assist]

Code Review

This pull request improves the date parsing logic in schedule_fn by adding support for more date formats, including those with fractional seconds. The change introduces a fallback mechanism to handle various timestamp formats gracefully. My review includes a suggestion to make the exception handling more specific to improve robustness and prevent masking unrelated errors.

[CorieW]

Hi @camillobucciarelli. Thank you for your contribution!

We'll be sure to review this and get back to you as soon as possible.

[BennetVellaExient]

Thank you very much @camillobucciarelli . Current state is scheduled functions deployed with python are breaking before getting started. We would very much like this in urgently.

The alternative I can think of is to kill off the scheduled setup and use a separate timed trigger on a plain https function...

[BennetVellaExient]

@CorieW Hi! Any estimates on this getting reviewed? Currently All firebase functions deployed in python that depend on a schedule are failing to even start...

[CorieW]

Hi @BennetVellaExient . We'll get this reviewed today.

[CorieW]

I like it. It's a lot more robust.

Comparison

[CorieW]

Ah, just noticed that there's a linting error that's been introduced. Could you possibly fix this linting error?

I believe the other errors (formatting and linting) were already happening.

[camillobucciarelli]

Ah, just noticed that there's a linting error that's been introduced. Could you possibly fix this linting error?

I believe the other errors (formatting and linting) were already happening.

I can but the linting error is on file dataconnect_fn.py, I didn't touch this file.

Do I proceed?

[CorieW]

@camillobucciarelli not that one, the one on src/firebase_functions/scheduler_fn.py:16:1

[taeold]

@camillobucciarelli thanks for the contribution! I fixed the lint errors and added a small unit test to cover the changes made. Looks good to me.

[taeold]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces a more robust date parsing mechanism in schedule_fn, which is a great improvement. The new implementation correctly handles various timestamp formats, including the 'Z' suffix for UTC, and provides a sensible fallback. The switch from the naive datetime.utcnow() to the aware datetime.now(timezone.utc) is also a good practice. I've added one comment regarding improving test coverage for the new parsing logic to ensure its robustness across different scenarios.