pasql pasql - 1 month ago 34
Python Question

Google Calendar Integration with Django

Is there a fully fledged Django-based example of a Google Calendar integration? I was reading through Google's example page but their link at the bottom is outdated.

I'm specifically struggeling with the refresh token as Google's examples focus solely on how to get the access token. That's what I have so far:

@staff_member_required
def authorize_access(request):
return redirect(get_flow(request).step1_get_authorize_url())

@staff_member_required
def oauth2_callback(request):
credentials = get_flow(request).step2_exchange(request.GET['code'])

store = get_store()
store.put(credentials)
credentials.set_store(store)

return redirect('...')

def get_flow(request):
flow = client.flow_from_clientsecrets(os.path.join(CREDENTIAL_DIR, CLIENT_SECRET_FILE),
SCOPES,
redirect_uri='%s://%s/google-calendar/oauth2-callback/' % (request.META['wsgi.url_scheme'], request.META['HTTP_HOST'],))
flow.params['access_type'] = 'offline'
flow.params['approval_prompt'] = 'force'

return flow

def get_store():
return oauth2client.file.Storage(os.path.join(CREDENTIAL_DIR, ACCESS_TOKEN_FILE))

def has_valid_api_credentials():
credentials = get_store().get()
return credentials is not None

def build_service():
credentials = get_store().get()

if not credentials:
return None
elif credentials.access_token_expired:
http = credentials.refresh(httplib2.Http())
http = get_store().get().authorize(http)
else:
http = credentials.authorize(httplib2.Http())

service = discovery.build('calendar', 'v3', http=http)

return service

def create_events(rental_request):
service = build_service()

event = service.events().insert(...).execute()

Answer

Researching a lot of different approaches I found out that server-to-server authentication is what I wanted. This way no user has to explicitly give permissions and acquired auth-tokens don't have to be renewed. Instead, using a service account, a server can make calls itself.

Before you can start coding, you have to setup such a service account and add it to your calendar that you want the service account to access. Google has written down the three steps to create an account here. Afterwards, go to https://calendar.google.com, locate on the left side of the screen the calendar you want to share with your new service account and click the triangle next to it. From the drop-down menu choose calendar settings. This takes you to a screen where you'll find the calendar-ID which you'll need later (so write it down) and also displays a tab at the top to share access to the calendar. As "person" insert the email address from the service account, give it the respective permissions and click save (if you don't click save the service account won't be added).

The code for this is actually pretty elegant:

import os
from datetime import timedelta
import datetime
import pytz

import httplib2
from googleapiclient.discovery import build
from oauth2client.service_account import ServiceAccountCredentials

service_account_email = 'XXX@YYY.iam.gserviceaccount.com'

CLIENT_SECRET_FILE = 'creds.p12'

SCOPES = 'https://www.googleapis.com/auth/calendar'
scopes = [SCOPES]

def build_service():
    credentials = ServiceAccountCredentials.from_p12_keyfile(
        service_account_email=service_account_email,
        filename=CLIENT_SECRET_FILE,
        scopes=SCOPES
    )

    http = credentials.authorize(httplib2.Http())

    service = build('calendar', 'v3', http=http)

    return service


def create_event():
    service = build_service()

    start_datetime = datetime.datetime.now(tz=pytz.utc)
    event = service.events().insert(calendarId='<YOUR EMAIL HERE>@gmail.com', body={
        'summary': 'Foo',
        'description': 'Bar',
        'start': {'dateTime': start_datetime.isoformat()},
        'end': {'dateTime': (start_datetime + timedelta(minutes=15)).isoformat()},
    }).execute()

    print(event)

I'm using oauth2client version 2.2.0 (pip install oauth2client).

I hope this answer helps :)