Add samples for ndb async ops.

Author: Jerjou Cheng

appengine/ndb/async/README.md

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+## App Engine Datastore NDB Asynchronous Operations Samples
+
+This contains snippets used in the NDB asynchronous operations documentation,
+demonstrating various ways to make asynchronous ndb operations.
+
+<!-- auto-doc-link -->
+These samples are used on the following documentation page:
+
+> https://cloud.google.com/appengine/docs/python/ndb/async
+
+<!-- end-auto-doc-link -->

appengine/ndb/async/app_async.py

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+# Copyright 2016 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the 'License');
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an 'AS IS' BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from google.appengine.api import users
+from google.appengine.ext import ndb
+import webapp2
+
+
+class Account(ndb.Model):
+    view_counter = ndb.IntegerProperty()
+
+
+class MyRequestHandler(webapp2.RequestHandler):
+    def get(self):
+        acct = Account.get_by_id(users.get_current_user().user_id())
+        acct.view_counter += 1
+        future = acct.put_async()
+
+        # ...read something else from Datastore...
+
+        self.response.out.write('Content of the page')
+        future.get_result()
+
+app = webapp2.WSGIApplication([('/', MyRequestHandler)])

appengine/ndb/async/app_async_test.py

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+# Copyright 2016 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import app_async
+import pytest
+import webtest
+
+
+@pytest.fixture
+def app(testbed):
+    return webtest.TestApp(app_async.app)
+
+
+def test_main(app, testbed, login):
+    app_async.Account(id='123', view_counter=4).put()
+
+    # Log the user in
+    login(id='123')
+
+    response = app.get('/')
+
+    assert response.status_int == 200
+    account = app_async.Account.get_by_id('123')
+    assert account.view_counter == 5

appengine/ndb/async/app_sync.py

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+# Copyright 2016 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the 'License');
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an 'AS IS' BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from google.appengine.api import users
+from google.appengine.ext import ndb
+import webapp2
+
+
+class Account(ndb.Model):
+    view_counter = ndb.IntegerProperty()
+
+
+class MyRequestHandler(webapp2.RequestHandler):
+    def get(self):
+        acct = Account.get_by_id(users.get_current_user().user_id())
+        acct.view_counter += 1
+        acct.put()
+
+        # ...read something else from Datastore...
+
+        self.response.out.write('Content of the page')
+
+app = webapp2.WSGIApplication([('/', MyRequestHandler)])

appengine/ndb/async/app_sync_test.py

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+# Copyright 2016 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import app_sync
+import pytest
+import webtest
+
+
+@pytest.fixture
+def app(testbed):
+    return webtest.TestApp(app_sync.app)
+
+
+def test_main(app, testbed, login):
+    app_sync.Account(id='123', view_counter=4).put()
+
+    # Log the user in
+    login(id='123')
+
+    response = app.get('/')
+
+    assert response.status_int == 200
+    account = app_sync.Account.get_by_id('123')
+    assert account.view_counter == 5

appengine/ndb/async/app_toplevel/README.md

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+This is in a separate folder to isolate it from the other apps.
+This is necessary because the test won't pass when run with the other tests.

appengine/ndb/async/app_toplevel/app_toplevel.py

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+# Copyright 2016 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the 'License');
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an 'AS IS' BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from google.appengine.api import users
+from google.appengine.ext import ndb
+import webapp2
+
+
+class Account(ndb.Model):
+    view_counter = ndb.IntegerProperty()
+
+
+class MyRequestHandler(webapp2.RequestHandler):
+    @ndb.toplevel
+    def get(self):
+        acct = Account.get_by_id(users.get_current_user().user_id())
+        acct.view_counter += 1
+        acct.put_async()  # Ignoring the Future this returns
+
+        # ...read something else from Datastore...
+
+        self.response.out.write('Content of the page')
+
+
+# This is actually redundant, since the `get` decorator already handles it, but
+# for demonstration purposes, you can also make the entire app toplevel with
+# the following.
+app = ndb.toplevel(webapp2.WSGIApplication([('/', MyRequestHandler)]))

appengine/ndb/async/app_toplevel/app_toplevel_test.py

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+# Copyright 2016 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import app_toplevel
+import pytest
+import webtest
+
+
+@pytest.fixture
+def app(testbed):
+    return webtest.TestApp(app_toplevel.app)
+
+
+def test_main(app, testbed, login):
+    app_toplevel.Account(id='123', view_counter=4).put()
+
+    # Log the user in
+    login(id='123')
+
+    response = app.get('/')
+
+    assert response.status_int == 200
+    account = app_toplevel.Account.get_by_id('123')
+    assert account.view_counter == 5

appengine/ndb/async/app_toplevel/index.html

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+# Copyright 2016 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the 'License');
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an 'AS IS' BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from google.appengine.api import users
+from google.appengine.ext import ndb
+import webapp2
+
+
+class Guestbook(ndb.Model):
+    content = ndb.StringProperty()
+    post_date = ndb.DateTimeProperty(auto_now_add=True)
+
+
+class Account(ndb.Model):
+    email = ndb.StringProperty()
+    nickname = ndb.StringProperty()
+
+    def nick(self):
+        return self.nickname or self.email  # Whichever is non-empty
+
+
+class Message(ndb.Model):
+    text = ndb.StringProperty()
+    when = ndb.DateTimeProperty(auto_now_add=True)
+    author = ndb.KeyProperty(kind=Account)  # references Account
+
+
+class MainPage(webapp2.RequestHandler):
+    def get(self):
+        if self.request.path == '/guestbook':
+            if self.request.get('async'):
+                self.get_guestbook_async()
+            else:
+                self.get_guestbook_sync()
+        elif self.request.path == '/messages':
+            if self.request.get('async'):
+                self.get_messages_async()
+            else:
+                self.get_messages_sync()
+
+    def get_guestbook_sync(self):
+        uid = users.get_current_user().user_id()
+        acct = Account.get_by_id(uid)  # I/O action 1
+        qry = Guestbook.query().order(-Guestbook.post_date)
+        recent_entries = qry.fetch(10)  # I/O action 2
+
+        # ...render HTML based on this data...
+        self.response.out.write('<html><body>{}</body></html>'.format(''.join(
+            '<p>{}</p>'.format(entry.content) for entry in recent_entries)))
+
+        return acct, qry
+
+    def get_guestbook_async(self):
+        uid = users.get_current_user().user_id()
+        acct_future = Account.get_by_id_async(uid)  # Start I/O action #1
+        qry = Guestbook.query().order(-Guestbook.post_date)
+        recent_entries_future = qry.fetch_async(10)  # Start I/O action #2
+        acct = acct_future.get_result()  # Complete #1
+        recent_entries = recent_entries_future.get_result()  # Complete #2
+
+        # ...render HTML based on this data...
+        self.response.out.write('<html><body>{}</body></html>'.format(''.join(
+            '<p>{}</p>'.format(entry.content) for entry in recent_entries)))
+
+        return acct, recent_entries
+
+    def get_messages_sync(self):
+        qry = Message.query().order(-Message.when)
+        for msg in qry.fetch(20):
+            acct = msg.author.get()
+            self.response.out.write(
+                '<p>On {}, {} wrote:'.format(msg.when, acct.nick()))
+            self.response.out.write('<p>{}'.format(msg.text))
+
+    def get_messages_async(self):
+        @ndb.tasklet
+        def callback(msg):
+            acct = yield msg.author.get_async()
+            raise ndb.Return('On {}, {} wrote:\n{}'.format(
+                msg.when, acct.nick(), msg.text))
+
+        qry = Message.query().order(-Message.when)
+        outputs = qry.map(callback, limit=20)
+        for output in outputs:
+            self.response.out.write('<p>{}</p>'.format(output))
+
+
+app = webapp2.WSGIApplication([
+    ('/.*', MainPage),
+], debug=True)