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https://github.com/googleapis/python-spanner-django

Cloud Spanner database backend for Django
https://github.com/googleapis/python-spanner-django

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Cloud Spanner database backend for Django

Lists

README 

        
Cloud Spanner support for Django

================================



|GA| |pypi| |versions|



`Cloud Spanner`_ is the world's first fully managed relational database service

to offer both strong consistency and horizontal scalability for

mission-critical online transaction processing (OLTP) applications. With Cloud

Spanner you enjoy all the traditional benefits of a relational database; but

unlike any other relational database service, Cloud Spanner scales horizontally

to hundreds or thousands of servers to handle the biggest transactional

workloads.



- `Client Library Documentation`_

- `Product Documentation`_



.. |GA| image:: https://img.shields.io/badge/support-GA-gold.svg

   :target: https://github.com/googleapis/google-cloud-python/blob/main/README.rst#general-availability

.. |pypi| image:: https://img.shields.io/pypi/v/django-google-spanner.svg

   :target: https://pypi.org/project/django-google-spanner/

.. |versions| image:: https://img.shields.io/pypi/pyversions/django-google-spanner.svg

   :target: https://pypi.org/project/django-google-spanner/

.. _Cloud Spanner: https://cloud.google.com/spanner/

.. _Client Library Documentation: https://googleapis.dev/python/django-google-spanner/latest/index.html

.. _Product Documentation:  https://cloud.google.com/spanner/docs



Quick Start

-----------



In order to use this library, you first need to go through the following steps:



1. `Select or create a Cloud Platform project.`_

2. `Enable billing for your project.`_

3. `Enable the Google Cloud Spanner API.`_

4. `Setup Authentication.`_



.. _Select or create a Cloud Platform project.: https://console.cloud.google.com/project

.. _Enable billing for your project.: https://cloud.google.com/billing/docs/how-to/modify-project#enable_billing_for_a_project

.. _Enable the Google Cloud Spanner API.:  https://cloud.google.com/spanner

.. _Setup Authentication.: https://googleapis.dev/python/google-api-core/latest/auth.html



This package provides a `3rd-party database backend

`__

for using `Cloud Spanner `__ with the `Django

ORM `__. It uses the `Cloud

Spanner Python client library `__

under the hood.



Installation

------------



Install this library in a `virtualenv`_ using pip. `virtualenv`_ is a tool to

create isolated Python and Django environments. The basic problem it addresses is one of

dependencies and versions, and indirectly permissions.



With `virtualenv`_, it's possible to install this library without needing system

install permissions, and without clashing with the installed system

dependencies.



.. _`virtualenv`: https://virtualenv.pypa.io/en/latest/



Supported versions

~~~~~~~~~~~~~~~~~~



The library supports `Django 2.2

`_, and `Django 3.2

`_.

Both versions are long-term support (LTS) releases for the

`Django project_`.

The minimum required Python version is 3.6.



.. code:: shell



    pip3 install django==3.2



Installing the package

~~~~~~~~~~~~~~~~~~~~~~



To install from PyPI:



.. code:: shell



    pip3 install django-google-spanner



To install from source:



.. code:: shell



    git clone [email protected]:googleapis/python-spanner-django.git

    cd python-spanner-django

    pip3 install -e .



Creating a Cloud Spanner instance and database

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



If you don't already have a Cloud Spanner database, or want to start from

scratch for a new Django application, you can `create a new instance

`__

and `database

`__

using the Google Cloud SDK:



.. code:: shell



    gcloud spanner instances create $INSTANCE --config=regional-us-central1 --description="New Django Instance" --nodes=1

    gcloud spanner databases create $DB --instance $INSTANCE



Configuring ``settings.py``

~~~~~~~~~~~~~~~~~~~~~~~~~~~



This package provides a Django application named ``django_spanner``. To use the

Cloud Spanner database backend, the application needs to installed and

configured:



-  Add ``django_spanner`` as the first entry in ``INSTALLED_APPS``:



   .. code:: python



       INSTALLED_APPS = [

           'django_spanner',

           ...

       ]



-  Edit the ``DATABASES`` setting to point to an existing Cloud Spanner database:



   .. code:: python



       DATABASES = {

           'default': {

               'ENGINE': 'django_spanner',

               'PROJECT': '$PROJECT',

               'INSTANCE': '$INSTANCE',

               'NAME': '$DATABASE',

           }

       }



Set credentials and project environment variables

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You'll need to download a service account JSON key file and point to it using an environment variable:



.. code:: shell



    export GOOGLE_APPLICATION_CREDENTIALS=/path/to/keyfile.json

    export GOOGLE_CLOUD_PROJECT=gcloud_project



Apply the migrations

~~~~~~~~~~~~~~~~~~~~



Please run:



.. code:: shell



    $ python3 manage.py migrate



That'll take a while to run. After this you should be able to see the tables and indexes created in your Cloud Spanner console.



Create a Django admin user

~~~~~~~~~~~~~~~~~~~~~~~~~~~

First you’ll need to create a user who can login to the admin site. Run the following command:



.. code:: shell



    $ python3 manage.py createsuperuser



which will then produce a prompt which will allow you to create your super user



.. code:: shell



    Username: admin

    Email address: [email protected]

    Password: **********

    Password (again): **********

    Superuser created successfully.



Login as admin

~~~~~~~~~~~~~~

Now, run the server



.. code:: shell



    python3 manage.py runserver



Then visit http://127.0.0.1:8000/admin/



Create and register your first model

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



Please follow the guides in https://docs.djangoproject.com/en/2.2/intro/tutorial02/#creating-models

to create and register the model to the Django’s automatically-generated admin site.



How it works

------------



Overall design

~~~~~~~~~~~~~~



.. figure:: https://raw.githubusercontent.com/googleapis/python-spanner-django/main/assets/overview.png

   :alt: "Overall Design"



Internals

~~~~~~~~~



.. figure:: https://raw.githubusercontent.com/googleapis/python-spanner-django/main/assets/internals.png

   :alt: "Internals"



Executing a query

~~~~~~~~~~~~~~~~~



Here is an example of how to add a row for Model Author, save it and later query it using Django



.. code:: shell



    >>> author_kent = Author( first_name="Arthur", last_name="Kent", rating=Decimal("4.1"),)

    >>> author_kent.save()

    >>> qs1 = Author.objects.all().values("first_name", "last_name")



How to contribute

~~~~~~~~~~~~~~~~~



Contributions to this library are always welcome and highly encouraged.



See `CONTRIBUTING `_ for more information on how to get started.



Please note that this project is released with a Contributor Code of Conduct.

By participating in this project you agree to abide by its terms. See the `Code 

of Conduct `_ for more information.



Limitations

~~~~~~~~~~~



Spanner has certain limitations of its own. The full set of limitations is documented

`here `__.

It is recommended that you go through that list.



Django spanner has a set of limitations as well, which you can find

`here `__.



Features from spanner that are not supported in Django-spanner are listed 

`here `__.