21 Feb 09 Event Calendar – Experiments with Google Calendar

I haven’t had a lot of time to explore implementing an event calendar with Google Calendar, but I did try a few things out. First of all, it is pretty easy to embed a Google Calendar into your website:

Google Calendar Embedded on Website

As I mentioned in the last post, I downloaded the Google Python gdata client library. I wrote a small Python script based on the provided example code. I was able to add events to my calendar from this Python script:

import gdata.calendar
import gdata.calendar.service
import gdata.service
import atom
import atom.service
import time

cal_client = gdata.calendar.service.CalendarService()
cal_client.email = 'xxx@gmail.com'
cal_client.password = 'xxx'
cal_client.source = 'Google-Calendar_Python_Sample-1.0'
cal_client.ProgrammaticLogin()

title = 'My Test Event from Python'
content = '''This is the content of the event in some fashion.
<a href="http://google.com">My Link</a>

http://surfguitar101.com.

<b>Bold</b> text.
<p>Here is a paragraph.</p>
<p>And another</p>
<ul><li>Item 1</li><li>Item 2</li></ul>
<img src="http://surfguitar101.com/modules/Forums/images/smiles/icon_cool.gif" alt="Smiley" />
'''
where = 'An undisclosed location.'
#cal_path = '/calendar/feeds/default/private/full'
cal_path = '/calendar/feeds/xxx@group.calendar.google.com/private/full'

event = gdata.calendar.CalendarEventEntry()
event.title = atom.Title(text=title)
event.content = atom.Content(text=content)
event.where.append(gdata.calendar.Where(value_string=where))

# Use current time for the start_time and have the event last 1 hour
start_time = time.strftime('%Y-%m-%dT%H:%M:%S.000Z', time.gmtime())
end_time = time.strftime('%Y-%m-%dT%H:%M:%S.000Z', time.gmtime(time.time() + 3600))
event.when.append(gdata.calendar.When(start_time=start_time, end_time=end_time))

new_event = cal_client.InsertEvent(event, cal_path)

As you can see, I was testing to see if I could insert HTML into the event, and if it would display correctly on the Google Calendar. According to my tests, it does appear you can insert simple HTML. The only thing that did not work was <img> tags. Unfortunately, if you log into your Google account, and then go to your Google Calendar and try to edit this event using the Google GUI, all HTML will be stripped. This will make it difficult to edit an existing event and will probably steer me towards keeping the user added event around in the database for future editing until that event has expired.

I have to say I am not really impressed with the Python API. It seems rather “un-Pythonic”. Why do I have to construct atom objects and assign them to the event title and content fields? The API should do this for me. Why do I have to format my own date strings? The API should accept Python datetime objects and do that for me. Pretty disappointing coming from Google.

I am starting to see a way forward here. I think I need to do the following:

• Build a view to let registered users submit events. Allow the event description to be submitted in Markdown format, but warn the user that images won’t work.
• In the admin interface, allow the admin to approve events by marking a boolean field in the database.
• Build a custom admin view that contains a form that prompts the admin for their  Google password, and batch inserts all approved events to the Google calendar.

Initially I will support only non-repeating events. I’ll go back and try to add support for repeating events in “phase 2″ once I get the above functionality working.

I was looking through the Django docs and came across a new feature in trunk that allows you to extend the set of URLs supported by a model in the admin section. This will allow me to create a custom admin view to insert the events. I think this is just a new way of doing something that was already supported, and is described in the online Django book. I’ll have to update my working copy of Django trunk and try this out.

Tags: calendar, django, gdata, google, sg101