Ndb migration sample (GoogleCloudPlatform#4067)

* Use google.cloud ndb for overview

* Moved NDB migration to migration/ path

* New NDB sample

* Pulled page out to a template

* Added requirements-test spec

* Lint fixes, switched to pytest

* Lint fixes

* Lint fix

* Python 2.7 library specified

Author: engelke

appengine/standard/migration/ndb/overview/README.md

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+## App Engine Datastore NDB Overview Sample
+
+[![Open in Cloud Shell][shell_img]][shell_link]
+
+[shell_img]: http://gstatic.com/cloudssh/images/open-btn.png
+[shell_link]: https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/GoogleCloudPlatform/python-docs-samples&page=editor&open_in_editor=appengine/standard/migration/ndb/overview/README.md
+
+This is a sample app for Google App Engine that demonstrates how to replace
+use of the [Datastore NDB Python API](https://cloud.google.com/appengine/docs/python/ndb/)
+with the [Google Cloud NDB library](https://googleapis.dev/python/python-ndb/latest/index.html).
+This library can be used not only on App Engine, but also other Python 3
+platforms.
+
+To deploy and run this sample in App Engine standard for Python 2.7:
+
+    pip install -t lib -r requirements.txt
+    gcloud app deploy
+
+To deploy and run this sample in App Engine standard for Python 3.7:
+
+    gcloud app deploy app3.yaml

appengine/standard/migration/ndb/overview/app.yaml

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+# This file specifies your Python application's runtime configuration
+# including URL routing, versions, static file uploads, etc. See
+# https://developers.google.com/appengine/docs/python/config/appconfig
+# for details.
+
+runtime: python27
+api_version: 1
+threadsafe: yes
+
+# Handlers define how to route requests to your application.
+handlers:
+# This handler tells app engine how to route requests to a WSGI application.
+# The script value is in the format <path.to.module>.<wsgi_application>
+# where <wsgi_application> is a WSGI application object.
+- url: .*  # This regex directs all routes to main.app
+  script: main.app
+
+libraries:
+- name: setuptools
+  version: 36.6.0
+- name: grpcio
+  version: 1.0.0

appengine/standard/migration/ndb/overview/app3.yaml

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+runtime: python38

appengine/standard/migration/ndb/overview/appengine_config.py

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+import pkg_resources
+from google.appengine.ext import vendor
+
+# Set path to your libraries folder.
+path = 'lib'
+# Add libraries installed in the path folder.
+vendor.add(path)
+# Add libraries to pkg_resources working set to find the distribution.
+pkg_resources.working_set.add_entry(path)

appengine/standard/migration/ndb/overview/favicon.ico

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+indexes:
+
+# AUTOGENERATED
+
+# This index.yaml is automatically updated whenever the dev_appserver
+# detects that a new type of query is run.  If you want to manage the
+# index.yaml file manually, remove the above marker line (the line
+# saying "# AUTOGENERATED").  If you want to manage some indexes
+# manually, move them above the marker line.  The index.yaml file is
+# automatically uploaded to the admin console when you next deploy
+# your application using appcfg.py.
+
+- kind: Greeting
+  ancestor: yes
+  properties:
+  - name: date
+    direction: desc

appengine/standard/migration/ndb/overview/index.yaml

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+# Copyright 2015 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.
+
+# [START all]
+from flask import Flask, redirect, render_template, request
+from google.cloud import ndb
+
+try:
+    from urllib import urlencode
+except Exception:
+    from urllib.parse import urlencode
+
+app = Flask(__name__)
+client = ndb.Client()
+
+
+# [START greeting]
+class Greeting(ndb.Model):
+    """Models an individual Guestbook entry with content and date."""
+    content = ndb.StringProperty()
+    date = ndb.DateTimeProperty(auto_now_add=True)
+# [END greeting]
+
+# [START query]
+    with client.context():
+        @classmethod
+        def query_book(cls, ancestor_key):
+            return cls.query(ancestor=ancestor_key).order(-cls.date)
+
+
+@app.route('/', methods=['GET'])
+def display_guestbook():
+    guestbook_name = request.args.get('guestbook_name', '')
+    print('GET guestbook name is {}'.format(guestbook_name))
+    with client.context():
+        ancestor_key = ndb.Key("Book", guestbook_name or "*notitle*")
+        greetings = Greeting.query_book(ancestor_key).fetch(20)
+# [END query]
+
+    greeting_blockquotes = [greeting.content for greeting in greetings]
+    return render_template(
+            'index.html',
+            greeting_blockquotes=greeting_blockquotes,
+            guestbook_name=guestbook_name
+        )
+
+
+# [START submit]
+@app.route('/sign', methods=['POST'])
+def update_guestbook():
+    # We set the parent key on each 'Greeting' to ensure each guestbook's
+    # greetings are in the same entity group.
+    guestbook_name = request.form.get('guestbook_name', '')
+    print('Guestbook name from the form: {}'.format(guestbook_name))
+
+    with client.context():
+        print('Guestbook name from the URL: {}'.format(guestbook_name))
+        greeting = Greeting(
+                parent=ndb.Key("Book", guestbook_name or "*notitle*"),
+                content=request.form.get('content', None)
+            )
+        greeting.put()
+# [END submit]
+
+    return redirect('/?' + urlencode({'guestbook_name': guestbook_name}))
+
+
+if __name__ == '__main__':
+    # This is used when running locally.
+    app.run(host='127.0.0.1', port=8080, debug=True)
+# [END all]

appengine/standard/migration/ndb/overview/main.py

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+# Copyright 2015 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 pytest
+
+
+@pytest.fixture
+def app():
+    import main
+    main.app.testing = True
+    return main.app.test_client()
+
+
+def test_app(app):
+    response = app.get('/')
+    assert response.status_code == 200

appengine/standard/migration/ndb/overview/main_test.py

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+pytest>=4.6.9

appengine/standard/migration/ndb/overview/requirements-test.txt

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+# Newer versions of rsa module are incompatible with Python 2.7
+rsa==4.0
+
+googleapis_common_protos
+google-cloud-ndb
+flask==1.1.2