Working with `datetime`

Standard Library

Mastering datetime

Handle timestamps like a pro: parsing ISO strings, building time zone–aware objects, and doing arithmetic safely.

Reference cheatsheetHandle time zones

Cheatsheet

Common datetime recipes

Task	Code
Current UTC time	datetime.datetime.utcnow()
Current local time	datetime.datetime.now()
Parse ISO string	datetime.datetime.fromisoformat('2024-03-13T09:00:00')
Format string	ts.strftime('%Y-%m-%d %H:%M')
Add 7 days	ts + datetime.timedelta(days=7)

Time zones

• Use the zoneinfo module (Python 3.9+) for IANA timezone data.

from datetime import datetime
from zoneinfo import ZoneInfo

now = datetime.now(ZoneInfo('UTC'))
local = now.astimezone(ZoneInfo('America/New_York'))

• Always store timestamps in UTC internally; convert at boundaries.

Best practices

• Use datetime.date for date-only values and datetime.time for time-only.
• Serialize to ISO 8601 strings for APIs (dt.isoformat()).
• Beware naive vs aware datetimes—mixing them raises TypeError.

Next up in your learning path

Manipulate files by timestamp

Combine datetime with pathlib for log rotation.

Filesystem

Schedule tasks

Use timedelta math for job scheduling.

Workflow

Format CLI output

Integrate formatted timestamps in argparse apps.

CLI