Park Life

Free music and movies in Minneapolis

parks via text messaging

Image credit: http://linden-hills.com/

Text

What is this?

An application that responds to text messages by sending information about free music and movie events in Minneapolis parks.

Text FUN to (763) 273-5353

Tools used:

Python
Google App Engine
Google Cloud Datastore
Twilio
Python libraries
flask, icalendar, pytz

Creating the project

Go to https://console.developers.google.com/project
Click on "Create Project"
Select "Try App Engine"
Download the sample project
Install the Google SDK if needed

Getting the data

Download calendar from Minneapolis Parks website
Convert from iCalendar format to JSON

from json import JSONEncoder
import json
from datetime import datetime
from icalendar import Calendar, vDDDTypes, Event

class ICalendarEncoder(JSONEncoder):
    def default(self, obj, markers=None):

        try:
            if obj.__module__.startswith("icalendar.prop"):
                return (obj.to_ical())
        except AttributeError:
            pass

        if isinstance(obj, datetime):
            return (obj.now().strftime('%Y-%m-%dT%H:%M:%S'))

        return JSONEncoder.default(self,obj)    


cal = Calendar.from_ical(open('basic.ics','rb').read())

event_list = []
for event in cal.walk(name="VEVENT"):
    suspect = json.dumps(event, cls=ICalendarEncoder)
    working = json.loads(suspect)
    event_list.append(working)
    
with open('cal.json', 'w') as f:
    cal_js = json.dumps(event_list)
    f.write(cal_js)

Creating the data model

# models.py
from google.appengine.ext import ndb

class Event(ndb.Model):
    summary = ndb.StringProperty()
    description = ndb.StringProperty()
    start = ndb.StringProperty()
    end = ndb.StringProperty()
    date = ndb.StringProperty()
    location = ndb.StringProperty()
    uid = ndb.StringProperty()

Loading into a database

# load.py
from flask import Flask
app = Flask(__name__)
app.config['DEBUG'] = True

import json
from models import Event
from util import utc_to_central, time_to_string

@app.route('/load')
def load():
    with open('cal.json') as f:
        events = json.load(f)
    for data in events:
        if 'RRULE' in data:  # Recurring event
            continue
        start = utc_to_central(data['DTSTART'])
        end = utc_to_central(data['DTEND'])
        date = "%d%02d%02d" % (start.year, start.month, start.day)
        start_time = time_to_string(start)
        end_time = time_to_string(end)

        event = Event(
            summary = data['SUMMARY'].strip(),
            description = data['DESCRIPTION'].strip(),
            date = date,
            start = start_time,
            end = end_time,
            location = data['LOCATION'].strip(),
            uid = data['UID'])
        event.put()
    return 'OK'

Utility functions

from datetime import datetime
from pytz import timezone
utc = timezone('utc')
central = timezone('US/Central')

def utc_to_central(s):
    dt = datetime.strptime(s, '%Y%m%dT%H%M%SZ')
    dt = utc.localize(dt)
    return dt.astimezone(central)

def today():
    dt = datetime.utcnow()
    dt = utc.localize(dt)
    dt = dt.astimezone(central)
    return datetime.strftime(dt, '%Y%m%d')

def time_to_string(t):
    s = str(1 + ((t.hour - 1) % 12))
    if t.minute:
        s += ':%02d' % t.minute
    if t.hour > 11:
        s += 'pm'
    else:
        s += 'am'
    return s

Responding to a text

# main.py
from flask import Flask
app = Flask(__name__)
app.config['DEBUG'] = True

from util import today
from models import Event
from google.appengine.ext import ndb
import twilio.twiml

@app.route('/message', methods=['GET', 'POST'])
def reply():
    query = Event.query(Event.date == today())
    messages = []
    for event in query:
        messages.append('%s %s (%s)' % 
                        (event.start, event.summary, event.location))
        response = twilio.twiml.Response()
        if len(messages) == 0:
            response.message('No events today')
        else:
            response.message(' | '.join(messages))
    return str(response)

Purchase a Twilio phone number
Set the SMS request url to http://your.site/message