gdata_feedfetcher/step3.py

   1 # Copyright (C) 2008 Google Inc.
   2 #
   3 # Licensed under the Apache License, Version 2.0 (the "License");
   4 # you may not use this file except in compliance with the License.
   5 # You may obtain a copy of the License at
   6 #
   7 #      http://www.apache.org/licenses/LICENSE-2.0
   8 #
   9 # Unless required by applicable law or agreed to in writing, software
  10 # distributed under the License is distributed on an "AS IS" BASIS,
  11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12 # See the License for the specific language governing permissions and
  13 # limitations under the License.
  14
  15
  16 __author__ = 'api.jscudder (Jeff Scudder)'
  17
  18
  19 import wsgiref.handlers
  20 import cgi
  21 from google.appengine.ext import webapp
  22 from google.appengine.api import users
  23 import atom.url
  24 import gdata.service
  25 import gdata.alt.appengine
  26 import settings
  27
  28
  29 class Fetcher(webapp.RequestHandler):
  30
  31   def get(self):
  32     # Write our pages title
  33     self.response.out.write("""<html><head><title>
  34         Google Data Feed Fetcher: read Google Data API Atom feeds</title>""")
  35     self.response.out.write('</head><body>')
  36     next_url = atom.url.Url('http', settings.HOST_NAME, path='/step3')
  37     # Allow the user to sign in or sign out
  38     if users.get_current_user():
  39       self.response.out.write('<a href="%s">Sign Out</a><br>' % (
  40           users.create_logout_url(str(next_url))))
  41     else:
  42       self.response.out.write('<a href="%s">Sign In</a><br>' % (
  43           users.create_login_url(str(next_url))))
  44
  45     # Initialize a client to talk to Google Data API services.
  46     client = gdata.service.GDataService()
  47     gdata.alt.appengine.run_on_appengine(client)
  48
  49     feed_url = self.request.get('feed_url')
  50
  51     session_token = None
  52     # Find the AuthSub token and upgrade it to a session token.
  53     auth_token = gdata.auth.extract_auth_sub_token_from_url(self.request.uri)
  54     if auth_token:
  55       # Upgrade the single-use AuthSub token to a multi-use session token.
  56       session_token = client.upgrade_to_session_token(auth_token)
  57     if session_token and users.get_current_user():
  58       # If there is a current user, store the token in the datastore and
  59       # associate it with the current user. Since we told the client to
  60       # run_on_appengine, the add_token call will automatically store the
  61       # session token if there is a current_user.
  62       client.token_store.add_token(session_token)
  63     elif session_token:
  64       # Since there is no current user, we will put the session token
  65       # in a property of the client. We will not store the token in the
  66       # datastore, since we wouldn't know which user it belongs to.
  67       # Since a new client object is created with each get call, we don't
  68       # need to worry about the anonymous token being used by other users.
  69       client.current_token = session_token
  70
  71     self.response.out.write('<div id="main">')
  72     self.fetch_feed(client, feed_url)
  73     self.response.out.write('</div>')
  74     self.response.out.write(
  75         '<div id="sidebar"><div id="scopes"><h4>Request a token</h4><ul>')
  76     self.response.out.write('<li><a href="%s">Google Documents</a></li>' % (
  77         client.GenerateAuthSubURL(
  78             next_url,
  79             ('http://docs.google.com/feeds/',), secure=False, session=True)))
  80     self.response.out.write('</ul></div><br/><div id="tokens">')
  81
  82   def fetch_feed(self, client, feed_url):
  83     # Attempt to fetch the feed.
  84     if not feed_url:
  85       self.response.out.write(
  86           'No feed_url was specified for the app to fetch.<br/>')
  87       example_url = atom.url.Url('http', settings.HOST_NAME, path='/step3',
  88           params={'feed_url':
  89               'http://docs.google.com/feeds/documents/private/full'}
  90           ).to_string()
  91       self.response.out.write('Here\'s an example query which will show the'
  92           ' XML for the feed listing your Google Documents <a '
  93           'href="%s">%s</a>' % (example_url, example_url))
  94       return
  95     try:
  96       response = client.Get(feed_url, converter=str)
  97       self.response.out.write(cgi.escape(response))
  98     except gdata.service.RequestError, request_error:
  99       # If fetching fails, then tell the user that they need to login to
 100       # authorize this app by logging in at the following URL.
 101       if request_error[0]['status'] == 401:
 102         # Get the URL of the current page so that our AuthSub request will
 103         # send the user back to here.
 104         next = atom.url.Url('http', settings.HOST_NAME, path='/step3',
 105           params={'feed_url': feed_url})
 106         # If there is a current user, we can request a session token, otherwise
 107         # we should ask for a single use token.
 108         auth_sub_url = client.GenerateAuthSubURL(next, feed_url,
 109             secure=False, session=True)
 110         self.response.out.write('<a href="%s">' % (auth_sub_url))
 111         self.response.out.write(
 112             'Click here to authorize this application to view the feed</a>')
 113       else:
 114         self.response.out.write(
 115             'Something went wrong, here is the error object: %s ' % (
 116                 str(request_error[0])))
 117
 118
 119 def main():
 120   application = webapp.WSGIApplication([('/.*', Fetcher),], debug=True)
 121   wsgiref.handlers.CGIHandler().run(application)
 122
 123
 124 if __name__ == '__main__':
 125   main()