SMS Polling and Voting¶
One great use of SMS is to get large groups to vote on something easily. Nearly everyone in the audience will have a cell phone in their pocket - why not let them send in their votes over SMS?
We’ll create a simple Twilio application to record and report votes via SMS.
Ballot Format¶
For this poll ballots don’t need a format. Voters will simply text their choice to your Twilio number.
For example, to vote for Twilio, you’d text the following:
twilio
To see all the votes, we’ll use the twilio-python helper library to fetch data from the Twilio REST API. Open main.py and add the following lines.
import webapp2
from twilio.rest import TwilioRestClient
client = TwilioRestClient("ACCOUNT_SID", "AUTH_TOKEN")
class HelloWorld(webapp2.RequestHandler):
def get(self):
self.response.write('Hello World!')
app = webapp2.WSGIApplication([
('/', HelloWorld),
], debug=True)
We’re creating a client to talk to the REST API. You’ll need to replace the ACCOUNT_SID and AUTH_TOKEN with your account credentials. Your credentials are located at the top of your account dashboard.
With the client created, we can now query the Twilio REST API for SMS messages.
import webapp2
from twilio.rest import TwilioRestClient
client = TwilioRestClient("ACCOUNT_SID", "AUTH_TOKEN")
class SmsVoting(webapp2.RequestHandler):
def get(self):
for msg in client.sms.messages.iter():
self.response.write(msg.body + "<br>")
class HelloWorld(webapp2.RequestHandler):
def get(self):
self.response.write('Hello World!')
app = webapp2.WSGIApplication([
('/', HelloWorld),
('/sms', SmsVoting),
], debug=True)
To view your votes, open the Google App Engine Launcher. Click the Run button and then Browse button. In the URL bar, add /sms to the URL and reload.
This page will fail if you have multiple Twilio phone numbers. To fix this problem, we’ll filter messages based on the To phone number. Replace NUMBER with one of your Twilio phone numbers. If you can’t remember your number, you’ll find them listed in the Twilio account portal.
import webapp2
from twilio.rest import TwilioRestClient
client = TwilioRestClient("ACCOUNT_SID", "AUTH_TOKEN")
class SmsVoting(webapp2.RequestHandler):
def get(self):
for msg in client.sms.messages.iter(to="NUMBER"):
self.response.write(msg.body + "<br>")
class HelloWorld(webapp2.RequestHandler):
def get(self):
self.response.write('Hello World!')
app = webapp2.WSGIApplication([
('/', HelloWorld),
('/sms', SmsVoting),
], debug=True)
Still, we’re only seeing the contents of the messages.
Tallying Votes¶
In our election participants can only vote once, therefore each message should count for a single vote. We’ll use a dictionary to keep track of votes.
Instead of just printing the message body we’ll print the message body and the number of votes it received.
import webapp2
from twilio.rest import TwilioRestClient
from collections import defaultdict
client = TwilioRestClient("ACCOUNT_SID", "AUTH_TOKEN")
class SmsVoting(webapp2.RequestHandler):
def get(self):
votes = defaultdict(int)
for msg in client.sms.messages.iter(to="NUMBER"):
votes[msg.body] += 1
for vote, total in votes.items():
self.response.write("{} {}<br>".format(total, vote))
class HelloWorld(webapp2.RequestHandler):
def get(self):
self.response.write('Hello World!')
app = webapp2.WSGIApplication([
('/', HelloWorld),
('/sms', SmsVoting),
], debug=True)
We can now see tallies. However, this code is very brittle. Votes for foo and Foo won’t count for the same thing. Let’s normalize the message bodies so that similar votes count for the same option.
import webapp2
from twilio.rest import TwilioRestClient
from collections import defaultdict
client = TwilioRestClient("ACCOUNT_SID", "AUTH_TOKEN")
class SmsVoting(webapp2.RequestHandler):
def get(self):
votes = defaultdict(int)
for msg in client.sms.messages.iter(to="NUMBER"):
votes[msg.body.upper().strip()] += 1
for vote, total in votes.items():
self.response.write("{} {}<br>".format(total, vote))
class HelloWorld(webapp2.RequestHandler):
def get(self):
self.response.write('Hello World!')
app = webapp2.WSGIApplication([
('/', HelloWorld),
('/sms', SmsVoting),
], debug=True)
Preventing Cheaters¶
Cheaters never prosper. And currently they don’t get caught either. Any person can vote any number of times. We’ll keep track of every number that’s already voted, only allowing them a single vote. To do this, phone numbers will be added to a set and checked before each vote is tallied.
import webapp2
from twilio.rest import TwilioRestClient
from collections import defaultdict
client = TwilioRestClient("ACCOUNT_SID", "AUTH_TOKEN")
class SmsVoting(webapp2.RequestHandler):
def get(self):
votes = defaultdict(int)
voted = set()
for msg in client.sms.messages.iter(to="NUMBER"):
if msg.from_ in voted:
continue
votes[msg.body.upper().strip()] += 1
voted.add(msg.from_)
for vote, total in votes.items():
self.response.write("{} {}\n".format(total, vote))
class HelloWorld(webapp2.RequestHandler):
def get(self):
self.response.write('Hello World!')
app = webapp2.WSGIApplication([
('/', HelloWorld),
('/sms', SmsVoting),
], debug=True)
Graphing the Results¶
No election is complete without graphs. Let’s take the results from the previous section and make some pretty graphs. We’ll use the Google Graph API due to its simplicity and price (free).
import urllib
import webapp2
from twilio.rest import TwilioRestClient
from collections import defaultdict
client = TwilioRestClient("ACCOUNT_SID", "AUTH_TOKEN")
class SmsVoting(webapp2.RequestHandler):
def get(self):
votes = defaultdict(int)
voted = set()
for msg in client.sms.messages.iter(to="NUMBER"):
if msg.from_ in voted:
continue
votes[msg.body.upper().strip()] += 1
voted.add(msg.from_)
url = "https://chart.googleapis.com/chart"
options = {
"cht": "pc",
"chs": "500x200",
"chd": "t:" + ",".join(map(str, votes.values())),
"chl": "|".join(votes.keys()),
}
image = '<img src="{}?{}">'.format(url, urllib.urlencode(options))
self.response.write(image)
class HelloWorld(webapp2.RequestHandler):
def get(self):
self.response.write('Hello World!')
app = webapp2.WSGIApplication([
('/', HelloWorld),
('/sms', SmsVoting),
], debug=True)
