google app engine quick example

gae_guestbook.py

import cgi

from google.appengine.ext import db
from google.appengine.api import users
from google.appengine.ext import webapp
from google.appengine.ext.webapp.util import run_wsgi_app

class Greeting(db.Model):
  author = db.UserProperty()
  content = db.StringProperty(multiline=True)
  date = db.DateTimeProperty(auto_now_add=True)

class MainPage(webapp.RequestHandler):
  def get(self):
    self.response.out.write('')

    greetings = db.GqlQuery("SELECT * FROM Greeting
                       ORDER BY date DESC LIMIT 10")

    for greeting in greetings:
      if greeting.author:
        self.response.out.write('<strong>%s</strong> wrote:' %
                                 greeting.author.nickname())
      else:
        self.response.out.write('An anonymous person wrote:')
      self.response.out.write('<blockquote>%s</blockquote>' %
                                 cgi.escape(greeting.content))

    # Write the submission form and the footer of the page
    self.response.out.write("""
          <form action="/sign" method="post">
          <div><textarea name="content" rows="3" cols="60" /><div>
          <div><input type="submit" value="Sign Guestbook"></div>
          </form>
          </body>
          </html>""")

class Guestbook(webapp.RequestHandler):
  def post(self):
    greeting = Greeting()

    if users.get_current_user():
      greeting.author = users.get_current_user()

    greeting.content = self.request.get('content')
    greeting.put()
    self.redirect('/')

application = webapp.WSGIApplication(
                                     [('/', MainPage),
                                      ('/sign', Guestbook)],
                                     debug=True)

def main():
  run_wsgi_app(application)

if __name__ == "__main__":
  main()