Timezone issue when trying to patch google tasks item

[longfangsong]

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Please run down the following list and make sure you've tried the usual "quick fixes":

• Search the issues already opened: https://github.com/googleapis/google-api-python-client/issues
• Search StackOverflow: https://stackoverflow.com/questions/tagged/google-cloud-platform+python

If you are still having issues, please be sure to include as much information as possible:

Environment details

• OS type and version: macOS 15.1.1 (24B91), arm64
• Python version: Python 3.13.0
• pip version: pip 24.2
• google-api-python-client version: 2.155.0

Steps to reproduce

1. Patch an item in a google tasks list with api
2. Read the result

Code example

from googleapiclient.discovery import build
from google.oauth2.credentials import Credentials
creds = Credentials(TOKEN)
service = build('tasks', 'v1', credentials=creds)

result = service.tasks().patch(
            tasklist="ZERNSFhRUWduTVFuOVV0UQ",
            task="elo1NllBMlJ4TERCZ3Nucg",
            body={'title': 'Subitem', 'status': 'needsAction', 'due': '2024-12-14T00:00:00+01:00', 'notes': None, 'parent': 'OXRUelVzcFNjYWphbTl6Wg'},
        ).execute()
print(result)

Note the timestamp is 2024-12-14T00:00:00+01:00.

The result is:

{'kind': 'tasks#task', 'id': 'elo1NllBMlJ4TERCZ3Nucg', 'etag': '"LTExNjY2OTMyNjc"', 'title': 'Subitem', 'updated': '2024-12-12T10:41:34.000Z', 'selfLink': 'https://www.googleapis.com/tasks/v1/lists/ZERNSFhRUWduTVFuOVV0UQ/tasks/elo1NllBMlJ4TERCZ3Nucg', 'parent': 'OXRUelVzcFNjYWphbTl6Wg', 'position': '00000000000000000000', 'status': 'needsAction', 'due': '2024-12-13T00:00:00.000Z', 'links': [], 'webViewLink': 'https://tasks.google.com/task/zZ56YA2RxLDBgsnr?sa=6'}

Note the timestamp is 2024-12-13T00:00:00.000Z.

Stack trace

NA

Making sure to follow these steps will guarantee the quickest resolution possible.

Thanks!

[bamjun]

The issue occurs because the due field was set using a local timezone offset like +01:00 (Europe timezone).
Google Tasks API internally stores the due field in UTC (Z) format.
Even if you send a local time with an offset, Google automatically converts it to UTC when saving.
Therefore, if you want to display the correct time in your local timezone (e.g., Europe/Paris), you need to manually convert it back when reading the API response.

✅ Solution:
When reading the due field from the API response, parse it as UTC and then convert it to your local timezone.

Here’s an example:

from datetime import datetime
from zoneinfo import ZoneInfo  # Python 3.9+ standard library
from googleapiclient.discovery import build
from google.oauth2.credentials import Credentials

# Set up credentials
creds = Credentials(TOKEN)
service = build('tasks', 'v1', credentials=creds)

# Patch the task
result = service.tasks().patch(
    tasklist="ZERNSFhRUWduTVFuOVV0UQ",
    task="elo1NllBMlJ4TERCZ3Nucg",
    body={
        'title': 'Subitem',
        'status': 'needsAction',
        'due': '2024-12-14T00:00:00+01:00',
        'notes': None,
        'parent': 'OXRUelVzcFNjYWphbTl6Wg',
    },
).execute()

# Convert 'due' field from UTC to Europe/Paris timezone
due_from_api = result.get('due')

if due_from_api:
    # Parse the UTC time
    utc_time = datetime.fromisoformat(due_from_api.replace('Z', '+00:00'))
    
    # Convert to Europe/Paris time
    paris_time = utc_time.astimezone(ZoneInfo('Europe/Paris'))
    
    print(f"Due time in Europe/Paris timezone: {paris_time.isoformat()}")

# Print the full result
print(result)

✅ Summary:

• Input: You can send the due time with a local timezone offset if necessary, but Google will store it in UTC.
• Output: Always manually convert the UTC time back to your desired local timezone (e.g., Europe/Paris) after reading the API response.

This way, you can correctly display the due time without any timezone confusion.