fix: Convert datetime instances to UTC while passing over the wire
#6023
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−38
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datetime instances to UTC while passing over the wiredatetime instances to UTC while passing over the wire
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Pull request overview
This PR implements UTC-based datetime serialization over the wire to ensure cross-platform consistency when passing datetime values between Python and Dart/Flutter. It addresses two issues: (1) Windows compatibility when calling astimezone() on out-of-range dates, and (2) timezone inconsistencies across platforms in web deployments.
Changes:
- Python encoder now converts naive datetimes to local timezone (with fallback for Windows compatibility), then normalizes all datetimes to UTC before serialization
- Dart decoder converts received UTC datetimes back to local time for UI display
- Dart encoder normalizes datetimes to UTC and formats ISO strings compatible with Python's
fromisoformat() - Date picker default values updated for consistency (adding explicit day parameters)
Reviewed changes
Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| sdk/python/packages/flet/src/flet/messaging/protocol.py | Added UTC normalization for datetime encoding with Windows compatibility fallback |
| packages/flet/lib/src/utils/time.dart | Added .toLocal() conversion when retrieving datetime values |
| packages/flet/lib/src/transport/flet_msgpack_encoder.dart | Convert datetimes to UTC and replace 'Z' suffix with '+00:00' for Python compatibility |
| packages/flet/lib/src/transport/flet_backend_channel_web_socket.dart | Added FletMsgpackDecoder to enable proper datetime decoding |
| packages/flet/lib/src/transport/flet_backend_channel_javascript_web.dart | Added FletMsgpackDecoder to enable proper datetime decoding |
| packages/flet/lib/src/controls/date_picker.dart | Added explicit day parameter (1) to DateTime constructor for consistency |
| sdk/python/packages/flet/docs/reference/environment-variables.md | Restructured documentation - moved boolean setting tip to top, changed headers from #### to ###, minor grammar improvements |
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| tz = datetime.timezone.utc | ||
| obj = obj.replace(tzinfo=tz or datetime.timezone.utc) | ||
| # Normalize to UTC to ensure cross-platform consistency. | ||
| obj = obj.astimezone(datetime.timezone.utc) |
Contributor
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Looks like in case with naive we call astimezone() twice: first converting to a local tz and then to UTC. We can convert naive to UTC right away, no?
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
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Fix #5923
Fix #5895
Summary by Sourcery
Normalize cross-platform date and time handling between Python backend and Dart/Flutter clients and update related documentation.
New Features:
Bug Fixes:
Enhancements:
Documentation: