google app engine in 40 minutes (the absolute essentials)
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Google App Engine in 40 Minutes
(The Absolute Essentials)
Paul Barry – Institute of Technology, Carlow in Ireland
PyCon Ireland 2011
Grab the slides:
http://paulbarry.itcarlow.ie/GAE.pdf
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The Absolute Essentials in 40 Minutes...
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What is Google App Engine?
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Cloud-based Application Deployment Environment
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Integrated Collection of Google APIs
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Guido's Playground
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Is App Engine “just another framework”?
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It is all about your data...
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Think of App Engine as a highly scalable,distributed database server that you can program
with Python 2.5...
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Think of App Engine as a highly scalable,distributed database server that you can program
with Python 2.5...
and (cough) Java and (cough, cough) Go
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MVC
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Let's solve a real problem...
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Step 1
Download the SDK from:
http://code.google.com/appengine/
and sign-up for an App Engine account ID
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Step 2
Create a new project...
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...by creating an app.yaml file
application: dwwgapp version: 1 runtime: python api_version: 1
handlers: - url: /static static_dir: static
- url: /.* script: dwwgapp.py
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Step 3
Model Your Data
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Create dwwgDB.py (1 of 3)
from google.appengine.ext import db
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Create dwwgDB.py (2 of 3)
from google.appengine.ext import db
class Sighting(db.Model):
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Create dwwgDB.py (3 of 3)
from google.appengine.ext import db
class Sighting(db.Model):name = db.StringProperty()email = db.StringProperty()date = db.DateProperty()time = db.TimeProperty()location = db.StringProperty()fin_type = db.StringProperty()whale_type = db.StringProperty()blow_type = db.StringProperty()wave_type = db.StringProperty()
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Step 4
Define your UI in HTML
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The header.html template
<html> <head>
<title>{{ title }}</title> </head> <body>
<h1>{{ title }}</h1>
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The footer.html template
<p> {{ links }} </p> </body>
</html>
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The form_start.html template
<form method=”POST” action=”/”> <table>
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The form_end.html
<tr><th> </th><td><input type="submit"
value="{{ sub_title }}"></td></tr>
</table> </form>
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Render some HTML
from google.appengine.ext.webapp import template
html = template.render('templates/header.html', {'title': 'Report a Possible Sighting'})
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Rendering a Page
from google.appengine.ext.webapp import template
html = template.render('templates/header.html',{'title': 'Report a Possible Sighting'})
html = html + template.render('templates/form_start.html', {})
# Do something in here to render the form?!?!?!?!?!?!?
html = html + template.render('templates/form_end.html',{'sub_title': 'Submit Sighting'})
html = html + template.render('templates/footer.html', {'links': ''})
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Step 5
Write code to render your form
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Django Forms to the Rescue!
from google.appengine.ext.db import djangoforms
import dwwgDB
class SightingForm(djangoforms.ModelForm):class Meta:
model = dwwgDB.Sighting
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Rendering a Page, Again
from google.appengine.ext.webapp import template
html = template.render('templates/header.html',{'title': 'Report a Possible Sighting'})
html = html + template.render('templates/form_start.html', {})
html = html + str(SightingForm())
html = html + template.render('templates/form_end.html',{'sub_title': 'Submit Sighting'})
html = html + template.render('templates/footer.html', {'links': ''})
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Step 6
Tie it all together with logic
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You need to start your webapp
from google.appengine.ext import webappfrom google.appengine.ext.webapp.util import run_wsgi_app
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app = webapp.WSGIApplication([('/.*', SightingInputPage)], debug=True)
def main(): run_wsgi_app(app)
if __name__ == '__main__': main()
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Remember the app.yaml file?
application: dwwgapp version: 1 runtime: python api_version: 1
handlers: - url: /static static_dir: static
- url: /.* script: dwwgapp.py
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Put this code in dwwgapp.py
from google.appengine.ext import webappfrom google.appengine.ext.webapp.util import run_wsgi_app
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app = webapp.WSGIApplication([('/.*', SightingInputPage)], debug=True)
def main(): run_wsgi_app(app)
if __name__ == '__main__': main()
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What's this SightingInputPage thing?
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class SightingInputPage(webapp.RequestHandler): def get(self): html = template.render('templates/header.html',
{'title': 'Report a Possible Sighting'}) html = html + template.render('templates/form_start.html', {}) html = html + str(SightingForm()) html = html + template.render('templates/form_end.html',
{'sub_title': 'Submit Sighting'}) html = html + template.render('templates/footer.html', {'links': ''}) self.response.out.write(html)
Responding to a GET Request
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Step 7
Take your local app for a spin
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Click the “Run” button...
or
$ dev_appserver.py dwwgapp
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Ta Da! :-(
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Looks kinda shitty, doesn't it?
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Add a little CSS goodness..
<link type="text/css" rel="stylesheet" href="/static/dwwg.css" /><link type="text/css" rel="stylesheet" href="/static/styledform.css" />
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...and some code to dwwgDB.py
_FINS = ['Falcate', 'Triangular', 'Rounded'] _WHALES = ['Humpback', 'Orca', 'Blue', 'Killer', 'Beluga', 'Fin', 'Gray', 'Sperm'] _BLOWS = ['Tall', 'Bushy', 'Dense'] _WAVES = ['Flat', 'Small', 'Moderate', 'Large', 'Breaking', 'High']
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location = db.StringProperty(multiline=True)fin_type = db.StringProperty(choices=_FINS) whale_type = db.StringProperty(choices=_WHALES) blow_type = db.StringProperty(choices=_BLOWS) wave_type = db.StringProperty(choices=_WAVES)
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Ta Da! :-)
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Step 8
Do something with your data
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You need to POST data!
POST data with put()
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class SightingInputPage(webapp.RequestHandler): def get(self): html = template.render('templates/header.html',
{'title': 'Report a Possible Sighting'}) html = html + template.render('templates/form_start.html', {}) html = html + str(SightingForm()) html = html + template.render('templates/form_end.html',
{'sub_title': 'Submit Sighting'}) html = html + template.render('templates/footer.html', {'links': ''}) self.response.out.write(html)
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class SightingInputPage(webapp.RequestHandler): def get(self): html = template.render('templates/header.html',
{'title': 'Report a Possible Sighting'}) html = html + template.render('templates/form_start.html', {}) html = html + str(SightingForm()) html = html + template.render('templates/form_end.html',
{'sub_title': 'Submit Sighting'}) html = html + template.render('templates/footer.html', {'links': ''}) self.response.out.write(html)
def post(self):
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class SightingInputPage(webapp.RequestHandler): def get(self): html = template.render('templates/header.html',
{'title': 'Report a Possible Sighting'}) html = html + template.render('templates/form_start.html', {}) html = html + str(SightingForm()) html = html + template.render('templates/form_end.html',
{'sub_title': 'Submit Sighting'}) html = html + template.render('templates/footer.html', {'links': ''}) self.response.out.write(html)
def post(self): new_sighting = dwwgDB.Sighting()
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class SightingInputPage(webapp.RequestHandler): def get(self): html = template.render('templates/header.html',
{'title': 'Report a Possible Sighting'}) html = html + template.render('templates/form_start.html', {}) html = html + str(SightingForm()) html = html + template.render('templates/form_end.html',
{'sub_title': 'Submit Sighting'}) html = html + template.render('templates/footer.html', {'links': ''}) self.response.out.write(html)
def post(self): new_sighting = dwwgDB.Sighting() new_sighting.name = self.request.get('name') new_sighting.email = self.request.get('email') new_sighting.date = self.request.get('date') new_sighting.time = self.request.get('time') new_sighting.location = self.request.get('location') new_sighting.fin_type = self.request.get('fin_type') new_sighting.whale_type = self.request.get('whale_type') new_sighting.blow_type =self.request.get('blow_type') new_sighting.wave_type = self.request.get('wave_type')
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class SightingInputPage(webapp.RequestHandler): def get(self): html = template.render('templates/header.html',
{'title': 'Report a Possible Sighting'}) html = html + template.render('templates/form_start.html', {}) html = html + str(SightingForm()) html = html + template.render('templates/form_end.html',
{'sub_title': 'Submit Sighting'}) html = html + template.render('templates/footer.html', {'links': ''}) self.response.out.write(html)
def post(self): new_sighting = dwwgDB.Sighting() new_sighting.name = self.request.get('name') new_sighting.email = self.request.get('email') new_sighting.date = self.request.get('date') new_sighting.time = self.request.get('time') new_sighting.location = self.request.get('location') new_sighting.fin_type = self.request.get('fin_type') new_sighting.whale_type = self.request.get('whale_type') new_sighting.blow_type =self.request.get('blow_type') new_sighting.wave_type = self.request.get('wave_type')
new_sighting.put()
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html = template.render('templates/header.html', {'title': 'Thank you!'}) html = html + "<p>Thank you for providing your sighting data.</p>" html = html + template.render('templates/footer.html', {'links': 'Enter <a href="/">another sighting</a>.'}) self.response.out.write(html)
And don't forget to say “Thanks!”
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Step 9
Deploy to Google's cloud
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Click the “Deploy” button...
or
$ appcfg.py upload dwwgapp/
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http://dwwgapp.appspot.com
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Step 10
Realise your not done...
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Damn That Spam!
Some smart-alec posted a sightingof a Great White Shark on the top
of Mount Leinster...
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What to do?
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A tiny config tweak to app.yaml...
application: dwwgapp version: 1 runtime: python api_version: 1
handlers: - url: /static static_dir: static
- url: /.* script: dwwgapp.py login: required
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...and two tiny code changes
Add this to the dwwgDB.py model:
which_user = db.UserProperty()
Add this to your post() method in dwwgapp.py:
new_sighting.which_user = users.get_current_user()
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http://dwwgapp.appspot.com
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http://appengine.google.com
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And after all that,what do you end up with?
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Happy Clients!
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Want to learn moreabout this talk's example code?
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Head First Python
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Don't forget to check out the App Engine Tutorial on Sunday
with Seán Murphy
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