[![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.

This sample also uses

[Memorystore for Redis](https://cloud.google.com/memorystore/docs/redis/redis-overview)

caching to improve NDB performance in some situations.

Prior to deploying this sample, a

[serverless VPC connector](https://cloud.google.com/vpc/docs/configure-serverless-vpc-access)

must be created and then a

[Memorystore for Redis instance](https://cloud.google.com/memorystore/docs/redis/quickstart-console)

on the same VPC. The IP address and port number of the Redis instance, and

the name of the VPC connector should be entered in either app.yaml

(for Python 2.7) or app3.yaml (for Python 3).

To deploy and run this sample in App Engine standard for Python 2.7:

pip install -t lib -r requirements.txt

gcloud app deploy app.yaml index.yaml

To deploy and run this sample in App Engine standard for Python 3.7:

gcloud app deploy app3.yaml index.yaml

runtime: python27

api_version: 1

threadsafe: yes

handlers:

- 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

env_variables:

REDIS_CACHE_URL: 'redis://<REDIS_HOST>:<REDIS_PORT>'

vpc_access_connector:

name: 'projects/<PROJECT_ID>/locations/<REGION>/connectors/<CONNECTOR_NAME>'

runtime: python38

env_variables:

REDIS_CACHE_URL: 'redis://<REDIS_HOST>:<REDIS_PORT>'

vpc_access_connector:

name: 'projects/<PROJECT_ID>/locations/<REGION>/connectors/<CONNECTOR_NAME>'

import pkg_resources

from google.appengine.ext import vendor

path = 'lib'

vendor.add(path)

pkg_resources.working_set.add_entry(path)

indexes:

- kind: Greeting

ancestor: yes

properties:

- name: date

direction: desc

from flask import Flask, redirect, render_template, request

from google.cloud import ndb

import logging

try:

from urllib import urlencode

except Exception:

from urllib.parse import urlencode

app = Flask(__name__)

client = ndb.Client()

try:

global_cache = ndb.RedisCache.from_environment()

except Exception:

logging.warning('Redis not available.')

global_cache = None

class Greeting(ndb.Model):

"""Models an individual Guestbook entry with content and date."""

content = ndb.StringProperty()

date = ndb.DateTimeProperty(auto_now_add=True)

with client.context(global_cache=global_cache):

@classmethod

def query_book(cls, ancestor_key):

return cls.query(ancestor=ancestor_key).order(-cls.date)

def display_guestbook():

guestbook_name = request.args.get('guestbook_name', '')

print('GET guestbook name is {}'.format(guestbook_name))

with client.context(global_cache=global_cache):

ancestor_key = ndb.Key("Book", guestbook_name or "*notitle*")

greetings = Greeting.query_book(ancestor_key).fetch(20)

greeting_blockquotes = [greeting.content for greeting in greetings]

return render_template(

'index.html',

greeting_blockquotes=greeting_blockquotes,

guestbook_name=guestbook_name

)

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(global_cache=global_cache):

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()

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)

import pytest

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

pytest==4.6.11; python_version < '3.0'

rsa==4.5; python_version < '3'

<title>Guestbook</title>

{% for greeting in greeting_blockquotes %}

<blockquote>{{ greeting }}</blockquote>

{% endfor %}

<form action="/sign" method="post">

<div>

<textarea name="content" rows="3" cols="60"></textarea>

</div>

<div>

<input type="submit" value="Sign Guestbook" />

<input type="hidden" name="guestbook_name" value="{{ guestbook_name }}"/>

</div>

</form>

<hr>

<form action="/" method="GET">

Guestbook name:

<input name="guestbook_name" value="{{guestbook_name}}" />

<input type="submit" value="switch" />

</form>

</html >