Using Cloud Datastore

You can use Google Cloud Datastore to store application data from your App Engine app. Cloud Datastore is a database built for automatic scaling, high performance, and ease of application development.

This document describes how to use the Google Cloud Client Library to store and retrieve data using Cloud Datastore in an App Engine app.

Prerequisites and setup

Follow the instructions in "Hello, World!" for Python on App Engine to set up your environment and project, and to understand how Python apps are structured in App Engine. Write down and save your project ID, because you will need it to run the sample application described in this document.

Clone the repository

Download (clone) the sample:

$ git clone https://github.com/GoogleCloudPlatform/python-docs-samples
$ cd python-docs-samples/appengine/flexible/datastore

Edit project configuration and set dependencies

Include the google-cloud-datastore library in requirements.txt. This is the client library for Cloud Datastore.

Flask==0.11.1
google-cloud-datastore==0.21.0
gunicorn==19.6.0
oauth2client==4.0.0

Application code

The sample application logs, retrieves, and displays visitor IPs. You can see that a log entry is a simple two-field class that is given the type visit, and is saved to Cloud Datastore using the put command. Then, the ten most recent visits are retrieved in descending order using the query() command.

@app.route('/')
def index():
    ds = datastore.Client()

    user_ip = request.remote_addr

    # Keep only the first two octets of the IP address.
    if is_ipv6(user_ip):
        user_ip = ':'.join(user_ip.split(':')[:2])
    else:
        user_ip = '.'.join(user_ip.split('.')[:2])

    entity = datastore.Entity(key=ds.key('visit'))
    entity.update({
        'user_ip': user_ip,
        'timestamp': datetime.datetime.utcnow()
    })

    ds.put(entity)

    query = ds.query(kind='visit', order=('-timestamp',))

    results = [
        'Time: {timestamp} Addr: {user_ip}'.format(**x)
        for x in query.fetch(limit=10)]

    output = 'Last 10 visits:\n{}'.format('\n'.join(results))

    return output, 200, {'Content-Type': 'text/plain; charset=utf-8'}

Using index.yaml files

The sample app performs simple queries. More elaborate Datastore queries require one or more indexes, which you must specify in an index.yaml file that you upload along with your app. This file may be created manually, or generated automatically while testing your app locally.

For more information

For complete information on Cloud Datastore, including optimizations and concepts, see the Cloud Datastore documentation.

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App Engine flexible environment for Python docs