Monday, June 26, 2017

Modifying events with the Google Calendar API

Introduction

In an earlier post, I introduced Python developers to adding events to users' calendars using the Google Calendar API. However, while being able to insert events is "interesting," it's only half the picture. If you want to give your users a more complete experience, modifying those events is a must-have. In this post, you'll learn how to modify existing events, and as a bonus, learn how to implement repeating events too.

In order to modify events, we need the full Calendar API scope:
  • 'https://www.googleapis.com/auth/calendar'—read-write access to Calendar
Skipping the OAuth2 boilerplate, once you have valid authorization credentials, create a service endpoint to the Calendar API like this:
GCAL = discovery.build('calendar', 'v3',
    http=creds.authorize(Http()))
Now you can send the API requests using this endpoint.

Using the Google Calendar API

Our sample script requires an existing Google Calendar event, so either create one programmatically with events().insert() & save its ID as we showed you in that earlier post, or use events().list() or events().get() to get the ID of an existing event.

While you can use an offset from GMT/UTC, such as the GMT_OFF variable from the event insert post, today's code sample "upgrades" to a more general IANA timezone solution. For Pacific Time, it's "America/Los_Angeles". The reason for this change is to allow events that survive across Daylight Savings Time shifts. IOW, a dinner at 7PM/1900 stays at 7PM as we cross fall and spring boundaries. This is especially important for events that repeat throughout the year. Yes, we are discussing recurrence in this post too, so it's particularly relevant.

Modifying calendar events

In the other post, the EVENT body constitutes an "event record" containing the information necessary to create a calendar entry—it consists of the event name, start & end times, and invitees. That record is an API resource which you created/accessed with the Calendar API via events().insert(). (What do you think the "R" in "URL" stands for anyway?!?) The Calendar API adheres to RESTful semantics in that the HTTP verbs match the actions you perform against a resource.

In today's scenario, let's assume that dinner from the other post didn't work out, but that you want to reschedule it. Furthermore, not only do you want to make that dinner happen again, but because you're good friends, you've made a commitment to do dinner every other month for the rest of the year, then see where things stand. Now that we know what we want, we have a choice.

There are two ways to modifying existing events in Calendar:
  1. events().patch() (HTTP PATCH)—"patch" 1 or more fields in resource
  2. events().update() (HTTP PUT)—replace/rewrite entire resource
Do you just update that resource with events().patch() or do you replace the entire resource with events().update()? To answer that question, ask yourself, "How many fields am I updating?" In our case, we only want to change the date and make this event repeat, so PATCH is a better solution. If instead, you also wanted to rename the event or switch dinner to another set of friends, you'd then be changing all the fields, so PUT would be a better solution in that case.

Using PATCH means you're just providing the deltas between the original & updated event, so the EVENT body this time reflects just those changes:
TIMEZONE = 'America/Los_Angeles'
EVENT = {
    'start':  {'dateTime': '2017-07-01T19:00:00', 'timeZone': TIMEZONE},
    'end':    {'dateTime': '2017-07-01T22:00:00', 'timeZone': TIMEZONE},
    'recurrence': ['RRULE:FREQ=MONTHLY;INTERVAL=2;UNTIL=20171231']
}

Repeating events

Something you haven't seen before is how to do repeating events. To do this, you need to define what’s known as a recurrence rule ("RRULE"), which answers the question of how often an event repeats. It looks somewhat cryptic but follows the RFC 5545 Internet standard which you can basically decode like this:
  • FREQ=MONTHLY—event to occur on a monthly basis...
  • INTERVAL=2—... but every two months (every other month)
  • UNTIL=20171231—... until this date
There are many ways events can repeat, so I suggest you look at all the examples at the RFC link above.

Finishing touches

Finally, provide the EVENT_ID and call events().patch():
EVENT_ID = YOUR_EVENT_ID_STR_HERE # use your own!
e = GCAL.events().patch(calendarId='primary', eventId=EVENT_ID,
        sendNotifications=True, body=EVENT).execute()
Keep in mind that in real life, your users may be accessing your app from their desktop or mobile devices, so you need to ensure you don't override an earlier change. In this regard, developers should use the If-Match header along with an ETag value to validate unique requests. For more information, check out the conditional modification page in the official docs.

The one remaining thing is to confirm on-screen that the calendar event was updated successfully. We do that by checking the return value—it should be an Event object with all the existing details as well as the modified fields:
print('''\
*** %r event (ID: %s) modified:
    Start: %s
    End:   %s
    Recurring (rule): %s
''' % (e['summary'].encode('utf-8'), e['id'], e['start']['dateTime'],
        e['end']['dateTime'], e['recurrence'][0]))
That's pretty much the entire script save for the OAuth2 boilerplate code we've explored previously. The script is posted below in its entirety, and if you add a valid event ID and run it, depending on the date/times you use, you'll see something like this:
$ python gcal_modify.py
*** 'Dinner with friends' event (ID: YOUR_EVENT_ID_STR_HERE) modified:
    Start: 2017-07-01T19:00:00-07:00
    End:   2017-07-01T22:00:00-07:00
    Recurring (rule): RRULE:FREQ=MONTHLY;UNTIL=20171231;INTERVAL=2
It also works with Python 3 with one slight nit/difference being the "b" prefix on from the event name due to converting from Unicode to bytes:
*** b'Dinner with friends' event...

Conclusion

Now you know how to modify events as well as make them repeat. To complete the example, below is the entire script for your convenience which runs on both Python 2 and Python 3 (unmodified!):
from __future__ import print_function
from apiclient.discovery import build
from httplib2 import Http
from oauth2client import file, client, tools

SCOPES = 'https://www.googleapis.com/auth/calendar'
store = file.Storage('storage.json')
creds = store.get()
if not creds or creds.invalid:
    flow = client.flow_from_clientsecrets('client_secret.json', SCOPES)
    creds = tools.run_flow(flow, store)
CAL = build('calendar', 'v3', http=creds.authorize(Http()))

TIMEZONE = 'America/Los_Angeles'
EVENT = {
    'start':  {'dateTime': '2017-07-01T19:00:00', 'timeZone': TIMEZONE},
    'end':    {'dateTime': '2017-07-01T22:00:00', 'timeZone': TIMEZONE},
    'recurrence': ['RRULE:FREQ=MONTHLY;INTERVAL=2;UNTIL=20171231']
}
EVENT_ID = YOUR_EVENT_ID_STR_HERE
e = GCAL.events().patch(calendarId='primary', eventId=EVENT_ID,
        sendNotifications=True, body=EVENT).execute()

print('''\
*** %r event (ID: %s) modified:
    Start: %s
    End:   %s
    Recurring (rule): %s
''' % (e['summary'].encode('utf-8'), e['id'], e['start']['dateTime'],
        e['end']['dateTime'], e['recurrence'][0]))
You can now customize this code for your own needs, for a mobile frontend, a server-side backend, or to access other Google APIs. If you want to learn more about using the Google Calendar API, check out the following resources:


Thursday, June 1, 2017

Managing Team Drives with Python and the Google Drive API

NOTE 1: Teams Drives is only available for G Suite Business users or higher. If you're developing an application for Team Drives, you'll need similar access.
NOTE 2: The code featured here is also available as a video + overview post as part of this series.

Introduction

Team Drives is a relatively new feature from the Google Drive team, created to solve some of the issues of a user-centric system in larger organizations. Team Drives are owned by an organization rather than a user and with its use, locations of files and folders won't be a mystery any more. While your users do have to be a G Suite Business (or higher) customer to use Team Drives, the good news for developers is that you won't have to write new apps from scratch or learn a completely different API.

Instead, Team Drives features are accessible through the same Google Drive API you've come to know so well with Python. In this post, we'll demonstrate a sample Python app that performs core features that all developers should be familiar with. By the time you've finished reading this post and the sample app, you should know how to:
  • Create Team Drives
  • Add members to Team Drives
  • Create a folder in Team Drives
  • Import/upload files to Team Drives folders

Using the Google Drive API

The demo script requires creating files and folders, so you do need full read-write access to Google Drive. The scope you need for that is:
  • 'https://www.googleapis.com/auth/drive' — Full (read-write) access to Google Drive
If you're new to using Google APIs, we recommend reviewing earlier posts & videos covering the setting up projects and the authorization boilerplate so that we can focus on the main app. Once we've authorized our app, assume you have a service endpoint to the API and have assigned it to the DRIVE variable.

Create Team Drives

New Team Drives can be created with DRIVE.teamdrives().create(). Two things are required to create a Team Drive: 1) you should name your Team Drive. To make the create process idempotent, you need to create a unique request ID so that any number of identical calls will still only result in a single Team Drive being created. It's recommended that developers use a language-specific UUID library. For Python developers, that's the uuid module. From the API response, we return the new Team Drive's ID. Check it out:
def create_td(td_name):
    request_id = str(uuid.uuid4())
    body = {'name': td_name}
    return DRIVE.teamdrives().create(body=body,
            requestId=request_id, fields='id').execute().get('id')

Add members to Team Drives

To add members/users to Team Drives, you only need to create a new permission, which can be done with  DRIVE.permissions().create(), similar to how you would share a file in regular Drive with another user.  The pieces of information you need for this request are the ID of the Team Drive, the new member's email address as well as the desired role... choose from: "organizer", "owner", "writer", "commenter", "reader". Here's the code:
def add_user(td_id, user, role='commenter'):
    body = {'type': 'user', 'role': role, 'emailAddress': user}
    return DRIVE.permissions().create(body=body, fileId=td_id,
            supportsTeamDrives=True, fields='id').execute().get('id')
Some additional notes on permissions: the user can only be bestowed permissions equal to or less than the person/admin running the script... IOW, they cannot grant someone else greater permission than what they have. Also, if a user has a certain role in a Team Drive, they can be granted greater access to individual elements in the Team Drive. Users who are not members of a Team Drive can still be granted access to Team Drive contents on a per-file basis.

Create a folder in Team Drives

Nothing to see here! Yep, creating a folder in Team Drives is identical to creating a folder in regular Drive, with DRIVE.files().create(). The only difference is that you pass in a Team Drive ID rather than regular Drive folder ID. Of course, you also need a folder name too. Here's the code:
def create_td_folder(td_id, folder):
    body = {'name': folder, 'mimeType': FOLDER_MIME, 'parents': [td_id]}
    return DRIVE.files().create(body=body,
            supportsTeamDrives=True, fields='id').execute().get('id')

Import/upload files to Team Drives folders

Uploading files to a Team Drives folder is also identical to to uploading to a normal Drive folder, and also done with DRIVE.files().create(). Importing is slightly different than uploading because you're uploading a file and converting it to a G Suite/Google Apps document format, i.e., uploading CSV as a Google Sheet, or plain text or Microsoft Word® file as Google Docs. In the sample app, we tackle the former:
def import_csv_to_td_folder(folder_id, fn, mimeType):
    body = {'name': fn, 'mimeType': mimeType, 'parents': [folder_id]}
    return DRIVE.files().create(body=body, media_body=fn+'.csv',
            supportsTeamDrives=True, fields='id').execute().get('id')
The secret to importing is the MIMEtype. That tells Drive whether you want conversion to a G Suite/Google Apps format (or not). The same is true for exporting. The import and export MIMEtypes supported by the Google Drive API can be found in my SO answer here.

Driver app

All these functions are great but kind-of useless without being called by a main application, so here we are:
FOLDER_MIME = 'application/vnd.google-apps.folder'
SOURCE_FILE = 'inventory' # on disk as 'inventory.csv'
SHEETS_MIME = 'application/vnd.google-apps.spreadsheet'

td_id = create_td('Corporate shared TD')
print('** Team Drive created')
perm_id = add_user(td_id, 'email@example.com')
print('** User added to Team Drive')
folder_id = create_td_folder(td_id, 'Manufacturing data')
print('** Folder created in Team Drive')
file_id = import_csv_to_td_folder(folder_id, SOURCE_FILE, SHEETS_MIME)
print('** CSV file imported as Google Sheets in Team Drives folder')
The first set of variables represent some MIMEtypes we need to use as well as the CSV file we're uploading to Drive and requesting it be converted to Google Sheets format. Below those definitions are calls to all four functions described above.

Conclusion

If you run the script, you should get output that looks something like this, with each print() representing each API call:
$ python3 td_demo.py
** Team Drive created
** User added to Team Drive
** Folder created in Team Drive
** CSV file imported as Google Sheets in Team Drives folder
When the script has completed, you should have a new Team Drives folder called "Corporate shared TD", and within, a folder named "Manufacturing data" which contains a Google Sheets file called "inventory".

Below is the entire script for your convenience which runs on both Python 2 and Python 3 (unmodified!)—by using, copying, and/or modifying this code or any other piece of source from this blog, you implicitly agree to its Apache2 license:
from __future__ import print_function
import uuid

from apiclient import discovery
from httplib2 import Http
from oauth2client import file, client, tools

SCOPES = 'https://www.googleapis.com/auth/drive'
store = file.Storage('storage.json')
creds = store.get()
if not creds or creds.invalid:
    flow = client.flow_from_clientsecrets('client_secret.json', SCOPES)
    creds = tools.run_flow(flow, store)
DRIVE = discovery.build('drive', 'v3', http=creds.authorize(Http()))

def create_td(td_name):
    request_id = str(uuid.uuid4()) # random unique UUID string
    body = {'name': td_name}
    return DRIVE.teamdrives().create(body=body,
            requestId=request_id, fields='id').execute().get('id')

def add_user(td_id, user, role='commenter'):
    body = {'type': 'user', 'role': role, 'emailAddress': user}
    return DRIVE.permissions().create(body=body, fileId=td_id,
            supportsTeamDrives=True, fields='id').execute().get('id')

def create_td_folder(td_id, folder):
    body = {'name': folder, 'mimeType': FOLDER_MIME, 'parents': [td_id]}
    return DRIVE.files().create(body=body,
            supportsTeamDrives=True, fields='id').execute().get('id')

def import_csv_to_td_folder(folder_id, fn, mimeType):
    body = {'name': fn, 'mimeType': mimeType, 'parents': [folder_id]}
    return DRIVE.files().create(body=body, media_body=fn+'.csv',
            supportsTeamDrives=True, fields='id').execute().get('id')

FOLDER_MIME = 'application/vnd.google-apps.folder'
SOURCE_FILE = 'inventory' # on disk as 'inventory.csv'... CHANGE!
SHEETS_MIME = 'application/vnd.google-apps.spreadsheet'

td_id = create_td('Corporate shared TD')
print('** Team Drive created')
perm_id = add_user(td_id, 'email@example.com') # CHANGE!
print('** User added to Team Drive')
folder_id = create_td_folder(td_id, 'Manufacturing data')
print('** Folder created in Team Drive')
file_id = import_csv_to_td_folder(folder_id, SOURCE_FILE, SHEETS_MIME)
print('** CSV file imported as Google Sheets in Team Drives folder')
As with our other code samples, you can now customize it to learn more about the API, integrate into other apps for your own needs, for a mobile frontend, sysadmin script, or a server-side backend!

Code challenge

Write a simple application that moves folders (and its files or folders) in regular Drive to Team Drives. Each folder you move should be a corresponding folder in Team Drives. Remember that files in Team Drives can only have one parent, and the same goes for folders.