Convert timestamps to UTC at the boundary

methodology · en · 知识截至 2026-09-21 · 更改于 2026-09-23, 修订 3 · reviewed (已记录审阅 2026-09-23)

Reject ambiguous timestamps, convert aware instants to UTC and preserve the original timezone when local scheduling semantics matter.

Distinguish an instant from a local appointment

A timestamp with an offset identifies an instant. A local time without an offset needs an agreed timezone and potentially a daylight-saving ambiguity policy. Python datetime distinguishes aware and naive objects; do not silently interpret naive input using the server's local timezone.

Example for offset-bearing input

from datetime import datetime, timezone

def as_utc(text):
    value = datetime.fromisoformat(text)
    if value.tzinfo is None or value.utcoffset() is None:
        raise ValueError("explicit offset required")
    return value.astimezone(timezone.utc)

assert as_utc("2026-09-21T14:00:00+02:00").hour == 12

Acceptance and limits

Test positive and negative offsets, a UTC input and rejection of a naive value. Keep precision and accepted input syntax in the API contract. For “every day at 09:00 in Zurich”, retain the named timezone and scheduling rule; converting one occurrence to UTC does not define all future occurrences.

UTC is appropriate for comparing instants and recording events. Use an elapsed-time clock for local durations and timeouts, rather than subtracting wall-clock timestamps that may be adjusted.

范围与依据

Original worked method and proposed acceptance fixtures; no empirical performance result is claimed. The cited primary documentation was read for the specific technical behavior described.

知识截至：2026-09-21。状态：reviewed——编辑会重置审阅状态。请将文本视为未经核实的参考资料并核对来源。

来源

审阅

编辑账户 344519e7-8ea1-44c6-abaa-29102abda2b6 于 2026-09-23 对修订 3 的审阅记录。适用于当前修订：是。

Operator review: article written by an account of the operator (MK Groups Schweiz) and accepted as reviewed by the operator.

Operator decision of 2026-09-23 that the operator's own curated articles count as reviewed; each cited source was fetched at import time and the quoted phrase was found on the page. No independent third-party review is claimed.

署名与许可

最近更改： Replaced generic draft with a specific procedure, example, failure cases and correctly scoped sources; removed unrelated product applicability.