Move sample from appengine-guestbook-namespaces-python

Author: Jerjou Cheng

appengine/datastore_namespaces/README.md

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+# Guestbook with Namespaces
+
+This application implements the Python [Guestbook sample][7] but uses
+datastore namespaces to keep values in separate places.
+
+Guestbook is an example application showing basic usage of Google App
+Engine. Users can read & write text messages and optionaly log-in with
+their Google account. Messages are stored in App Engine (NoSQL)
+High Replication Datastore (HRD) and retrieved using a strongly consistent
+(ancestor) query.
+
+## Products
+- [App Engine][1]
+
+## Language
+- [Python][2]
+
+## APIs
+- [NDB Datastore API][3]
+- [Users API][4]
+
+## Dependencies
+- [webapp2][5]
+- [jinja2][6]
+
+[1]: https://developers.google.com/appengine
+[2]: https://python.org
+[3]: https://developers.google.com/appengine/docs/python/ndb/
+[4]: https://developers.google.com/appengine/docs/python/users/
+[5]: http://webapp-improved.appspot.com/
+[6]: http://jinja.pocoo.org/docs/
+[7]: https://github.com/GoogleCloudPlatform/appengine-guestbook-python/tree/part6-staticfiles

appengine/datastore_namespaces/__init__.py

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+application: guestbook-namespaces
+version: 1
+runtime: python27
+api_version: 1
+threadsafe: true
+
+handlers:
+- url: /stylesheets
+  static_dir: stylesheets
+
+- url: /.*
+  script: guestbook.application
+
+libraries:
+- name: webapp2
+  version: latest
+- name: jinja2
+  version: latest

appengine/datastore_namespaces/app.yaml

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+# Copyright 2010 Google Inc. All Rights Reserved.
+
+"""
+Manages the namespace for the application.
+
+This file presents ways an ISV (Independent Software Vendor) might use
+namespaces to distribute the guestbook application to different corporate
+clients. The original guestbook.py is left unchanged. Our namespace choosing
+hook is run when datastore or memcache attempt to resolve the namespace.
+When defined in appengine_config.py the lib_config mechanism substitutes this
+function for the default definition which returns None. This hopefully shows
+how easy it can be to make an existing app namespace aware.
+
+Setting _NAMESPACE_PICKER has the following effects:
+
+If _USE_SERVER_NAME, we read the server name
+foo.guestbook-isv.appspot.com and set the namespace.
+
+If _USE_GOOGLE_APPS_DOMAIN, we allow the namespace manager to infer the
+namespace from the request.
+
+If _USE_COOKIE, then the ISV might have a gateway page that sets a cookie
+called 'namespace' for example, and we read this cookie and set the namespace
+to its value.  Note this is not a secure use of cookies.
+
+Other possibilities not implemented here include using a mapping from user to
+namespace and possibly setting a namespace cookie from this mapping. If the
+mapping is stored in datastore, we would probably not wish to look it up on
+every query.
+"""
+
+__author__ = 'nverne@google.com (Nicholas Verne)'
+
+
+import Cookie
+import os
+
+from google.appengine.api import namespace_manager
+
+
+_USE_SERVER_NAME = 0
+_USE_GOOGLE_APPS_DOMAIN = 1
+_USE_COOKIE = 2
+
+_NAMESPACE_PICKER = _USE_SERVER_NAME
+
+
+def namespace_manager_default_namespace_for_request():
+    """Determine which namespace is to be used for a request.
+
+    The value of _NAMESPACE_PICKER has the following effects:
+
+    If _USE_SERVER_NAME, we read server name
+    foo.guestbook-isv.appspot.com and set the namespace.
+
+    If _USE_GOOGLE_APPS_DOMAIN, we allow the namespace manager to infer
+    the namespace from the request.
+
+    If _USE_COOKIE, then the ISV might have a gateway page that sets a
+    cookie called 'namespace', and we set the namespace to the cookie's value
+    """
+    name = None
+
+    if _NAMESPACE_PICKER == _USE_SERVER_NAME:
+        name = os.environ['SERVER_NAME']
+    elif _NAMESPACE_PICKER == _USE_GOOGLE_APPS_DOMAIN:
+        name = namespace_manager.google_apps_namespace()
+    elif _NAMESPACE_PICKER == _USE_COOKIE:
+        cookies = os.getenv('HTTP_COOKIE', None)
+        if cookies:
+            name = Cookie.BaseCookie(cookies).get('namespace')
+
+    return name

appengine/datastore_namespaces/appengine_config.py

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+import os
+import urllib
+
+from google.appengine.api import users
+from google.appengine.ext import ndb
+
+import jinja2
+
+import webapp2
+
+JINJA_ENVIRONMENT = jinja2.Environment(
+    loader=jinja2.FileSystemLoader(os.path.dirname(__file__)),
+    extensions=['jinja2.ext.autoescape'])
+
+DEFAULT_GUESTBOOK_NAME = 'default_guestbook'
+
+
+# We set a parent key on the 'Greetings' to ensure that they are all in the
+# same entity group. Queries across the single entity group will be consistent.
+# However, the write rate should be limited to ~1/second.
+
+def guestbook_key(guestbook_name=DEFAULT_GUESTBOOK_NAME):
+    """Constructs a Datastore key for a Guestbook entity with guestbook_name"""
+    return ndb.Key('Guestbook', guestbook_name)
+
+
+class Greeting(ndb.Model):
+    """Models an individual Guestbook entry with author, content, and date."""
+    author = ndb.UserProperty()
+    content = ndb.StringProperty(indexed=False)
+    date = ndb.DateTimeProperty(auto_now_add=True)
+
+
+class MainPage(webapp2.RequestHandler):
+
+    def get(self):
+        guestbook_name = self.request.get('guestbook_name',
+                                          DEFAULT_GUESTBOOK_NAME)
+        greetings_query = Greeting.query(
+            ancestor=guestbook_key(guestbook_name)).order(-Greeting.date)
+        greetings = greetings_query.fetch(10)
+
+        if users.get_current_user():
+            url = users.create_logout_url(self.request.uri)
+            url_linktext = 'Logout'
+        else:
+            url = users.create_login_url(self.request.uri)
+            url_linktext = 'Login'
+
+        template_values = {
+            'greetings': greetings,
+            'guestbook_name': urllib.quote_plus(guestbook_name),
+            'url': url,
+            'url_linktext': url_linktext,
+        }
+
+        template = JINJA_ENVIRONMENT.get_template('index.html')
+        self.response.write(template.render(template_values))
+
+
+class Guestbook(webapp2.RequestHandler):
+
+    def post(self):
+        # We set the same parent key on the 'Greeting' to ensure each Greeting
+        # is in the same entity group. Queries across the single entity group
+        # will be consistent. However, the write rate to a single entity group
+        # should be limited to ~1/second.
+        guestbook_name = self.request.get('guestbook_name',
+                                          DEFAULT_GUESTBOOK_NAME)
+        greeting = Greeting(parent=guestbook_key(guestbook_name))
+
+        if users.get_current_user():
+            greeting.author = users.get_current_user()
+
+        greeting.content = self.request.get('content')
+        greeting.put()
+
+        query_params = {'guestbook_name': guestbook_name}
+        self.redirect('/?' + urllib.urlencode(query_params))
+
+
+application = webapp2.WSGIApplication([
+    ('/', MainPage),
+    ('/sign', Guestbook),
+], debug=True)

appengine/datastore_namespaces/guestbook.py

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+<!DOCTYPE html>
+{% autoescape true %}
+<html>
+
+  <head>
+    <link type="text/css" rel="stylesheet" href="/stylesheets/main.css" />
+  </head>
+
+  <body>
+    {% for greeting in greetings %}
+      {% if greeting.author %}
+        <b>{{ greeting.author.nickname() }}</b> wrote:
+      {% else %}
+       An anonymous person wrote:
+      {% endif %}
+      <blockquote>{{ greeting.content }}</blockquote>
+    {% endfor %}
+
+    <form action="/sign?guestbook_name={{ guestbook_name }}" method="post">
+      <div><textarea name="content" rows="3" cols="60"></textarea></div>
+      <div><input type="submit" value="Sign Guestbook"></div>
+    </form>
+
+    <hr>
+
+    <form>Guestbook name:
+      <input value="{{ guestbook_name }}" name="guestbook_name">
+      <input type="submit" value="switch">
+    </form>
+
+    <a href="{{ url|safe }}">{{ url_linktext }}</a>
+
+  </body>
+</html>
+{% endautoescape %}

appengine/datastore_namespaces/index.html

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+indexes:
+- kind: Greeting
+  ancestor: yes
+  properties:
+  - name: date
+    direction: desc

appengine/datastore_namespaces/index.yaml

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+body {
+  font-family: Verdana, Helvetica, sans-serif;
+  background-color: #DDDDDD;
+}