|
1 | | -.. include:: ../README.rst |
| 1 | +Cloud Spanner support for Django |
| 2 | +================================ |
| 3 | + |
| 4 | +|GA| |pypi| |versions| |
| 5 | + |
| 6 | +`Cloud Spanner`_ is the world's first fully managed relational database service |
| 7 | +to offer both strong consistency and horizontal scalability for |
| 8 | +mission-critical online transaction processing (OLTP) applications. With Cloud |
| 9 | +Spanner you enjoy all the traditional benefits of a relational database; but |
| 10 | +unlike any other relational database service, Cloud Spanner scales horizontally |
| 11 | +to hundreds or thousands of servers to handle the biggest transactional |
| 12 | +workloads. |
| 13 | + |
| 14 | + |
| 15 | +- `Client Library Documentation`_ |
| 16 | +- `Product Documentation`_ |
| 17 | + |
| 18 | +.. |GA| image:: https://img.shields.io/badge/support-GA-gold.svg |
| 19 | + :target: https://github.com/googleapis/google-cloud-python/blob/main/README.rst#general-availability |
| 20 | +.. |pypi| image:: https://img.shields.io/pypi/v/django-google-spanner.svg |
| 21 | + :target: https://pypi.org/project/django-google-spanner/ |
| 22 | +.. |versions| image:: https://img.shields.io/pypi/pyversions/django-google-spanner.svg |
| 23 | + :target: https://pypi.org/project/django-google-spanner/ |
| 24 | +.. _Cloud Spanner: https://cloud.google.com/spanner/ |
| 25 | +.. _Client Library Documentation: https://googleapis.dev/python/django-google-spanner/latest/index.html |
| 26 | +.. _Product Documentation: https://cloud.google.com/spanner/docs |
| 27 | + |
| 28 | +Quick Start |
| 29 | +----------- |
| 30 | + |
| 31 | +In order to use this library, you first need to go through the following steps: |
| 32 | + |
| 33 | +1. `Select or create a Cloud Platform project.`_ |
| 34 | +2. `Enable billing for your project.`_ |
| 35 | +3. `Enable the Google Cloud Spanner API.`_ |
| 36 | +4. `Setup Authentication.`_ |
| 37 | + |
| 38 | +.. _Select or create a Cloud Platform project.: https://console.cloud.google.com/project |
| 39 | +.. _Enable billing for your project.: https://cloud.google.com/billing/docs/how-to/modify-project#enable_billing_for_a_project |
| 40 | +.. _Enable the Google Cloud Spanner API.: https://cloud.google.com/spanner |
| 41 | +.. _Setup Authentication.: https://googleapis.dev/python/google-api-core/latest/auth.html |
| 42 | + |
| 43 | +This package provides a `3rd-party database backend |
| 44 | +<https://docs.djangoproject.com/en/4.2/ref/databases/#using-a-3rd-party-database-backend>`__ |
| 45 | +for using `Cloud Spanner <https://cloud.google.com/spanner>`__ with the `Django |
| 46 | +ORM <https://docs.djangoproject.com/en/4.2/topics/db/>`__. It uses the `Cloud |
| 47 | +Spanner Python client library <https://github.com/googleapis/python-spanner>`__ |
| 48 | +under the hood. |
| 49 | + |
| 50 | +Installation |
| 51 | +------------ |
| 52 | + |
| 53 | +Install this library in a `virtualenv`_ using pip. `virtualenv`_ is a tool to |
| 54 | +create isolated Python and Django environments. The basic problem it addresses is one of |
| 55 | +dependencies and versions, and indirectly permissions. |
| 56 | + |
| 57 | +With `virtualenv`_, it's possible to install this library without needing system |
| 58 | +install permissions, and without clashing with the installed system |
| 59 | +dependencies. |
| 60 | + |
| 61 | +.. _`virtualenv`: https://virtualenv.pypa.io/en/latest/ |
| 62 | + |
| 63 | + |
| 64 | +Supported versions |
| 65 | +~~~~~~~~~~~~~~~~~~ |
| 66 | + |
| 67 | +The library supports `Django 3.2 |
| 68 | +<https://docs.djangoproject.com/en/3.2/>`_, and `Django 4.2 |
| 69 | +<https://docs.djangoproject.com/en/4.2/>`_. |
| 70 | +Both versions are long-term support (LTS) releases for the |
| 71 | +`Django project<https://www.djangoproject.com/download/#supported-versions>_`. |
| 72 | +The minimum required Python version is 3.6. |
| 73 | + |
| 74 | +.. code:: shell |
| 75 | +
|
| 76 | + pip3 install django==3.2 |
| 77 | +
|
| 78 | +
|
| 79 | +Installing the package |
| 80 | +~~~~~~~~~~~~~~~~~~~~~~ |
| 81 | + |
| 82 | +To install from PyPI: |
| 83 | + |
| 84 | +.. code:: shell |
| 85 | +
|
| 86 | + pip3 install django-google-spanner |
| 87 | +
|
| 88 | +
|
| 89 | +To install from source: |
| 90 | + |
| 91 | +.. code:: shell |
| 92 | +
|
| 93 | + git clone git@github.com:googleapis/google-cloud-python.git |
| 94 | + cd python-spanner-django |
| 95 | + pip3 install -e . |
| 96 | +
|
| 97 | +
|
| 98 | +Creating a Cloud Spanner instance and database |
| 99 | +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| 100 | + |
| 101 | +If you don't already have a Cloud Spanner database, or want to start from |
| 102 | +scratch for a new Django application, you can `create a new instance |
| 103 | +<https://cloud.google.com/spanner/docs/getting-started/python#create_an_instance>`__ |
| 104 | +and `database |
| 105 | +<https://cloud.google.com/spanner/docs/getting-started/python#create_a_database>`__ |
| 106 | +using the Google Cloud SDK: |
| 107 | + |
| 108 | +.. code:: shell |
| 109 | +
|
| 110 | + gcloud spanner instances create $INSTANCE --config=regional-us-central1 --description="New Django Instance" --nodes=1 |
| 111 | + gcloud spanner databases create $DB --instance $INSTANCE |
| 112 | +
|
| 113 | +
|
| 114 | +Configuring ``settings.py`` |
| 115 | +~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| 116 | + |
| 117 | +This package provides a Django application named ``django_spanner``. To use the |
| 118 | +Cloud Spanner database backend, the application needs to installed and |
| 119 | +configured: |
| 120 | + |
| 121 | +- Add ``django_spanner`` as the first entry in ``INSTALLED_APPS``: |
| 122 | + |
| 123 | + .. code:: python |
| 124 | +
|
| 125 | + INSTALLED_APPS = [ |
| 126 | + 'django_spanner', |
| 127 | + ... |
| 128 | + ] |
| 129 | +
|
| 130 | +- Edit the ``DATABASES`` setting to point to an existing Cloud Spanner database: |
| 131 | + |
| 132 | + .. code:: python |
| 133 | +
|
| 134 | + DATABASES = { |
| 135 | + 'default': { |
| 136 | + 'ENGINE': 'django_spanner', |
| 137 | + 'PROJECT': '$PROJECT', |
| 138 | + 'INSTANCE': '$INSTANCE', |
| 139 | + 'NAME': '$DATABASE', |
| 140 | + } |
| 141 | + } |
| 142 | +
|
| 143 | +Configuring primary key generation |
| 144 | +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| 145 | + |
| 146 | +The Spanner Django engine by default uses random int64 values that are generated |
| 147 | +by the client as primary key values. This default is applied to all databases that are |
| 148 | +configured, including databases that use a different engine than Spanner. You can |
| 149 | +disable this behavior with the RANDOM_ID_GENERATION_ENABLED setting: |
| 150 | + |
| 151 | + .. code:: python |
| 152 | +
|
| 153 | + DATABASES = { |
| 154 | + 'default': { |
| 155 | + 'ENGINE': 'django_spanner', |
| 156 | + 'PROJECT': '$PROJECT', |
| 157 | + 'INSTANCE': '$INSTANCE', |
| 158 | + 'NAME': '$DATABASE', |
| 159 | + 'RANDOM_ID_GENERATION_ENABLED': false, |
| 160 | + } |
| 161 | + } |
| 162 | +
|
| 163 | +
|
| 164 | +
|
| 165 | +Transaction support in autocommit mode |
| 166 | +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| 167 | + |
| 168 | +Django version 4.2 and higher by default supports transactions in autocommit mode. |
| 169 | +A transaction is automatically started if you define an |
| 170 | +[atomic block](https://docs.djangoproject.com/en/4.2/topics/db/transactions/#controlling-transactions-explicitly). |
| 171 | + |
| 172 | +Django version 3.2 and earlier did not support transactions in autocommit mode with Spanner. |
| 173 | +You can enable transactions in autocommit mode with Spanner with the |
| 174 | +`ALLOW_TRANSACTIONS_IN_AUTO_COMMIT` configuration option. |
| 175 | + |
| 176 | +- To enable transactions in autocommit mode in V3.2, set the flag `ALLOW_TRANSACTIONS_IN_AUTO_COMMIT` to True in your settings.py file. |
| 177 | +- To disable transactions in autocommit mode in V4.2, set the flag `ALLOW_TRANSACTIONS_IN_AUTO_COMMIT` to False in your settings.py file. |
| 178 | + |
| 179 | + |
| 180 | +Set credentials and project environment variables |
| 181 | +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| 182 | +You'll need to download a service account JSON key file and point to it using an environment variable: |
| 183 | + |
| 184 | +.. code:: shell |
| 185 | +
|
| 186 | + export GOOGLE_APPLICATION_CREDENTIALS=/path/to/keyfile.json |
| 187 | + export GOOGLE_CLOUD_PROJECT=gcloud_project |
| 188 | +
|
| 189 | +
|
| 190 | +Apply the migrations |
| 191 | +~~~~~~~~~~~~~~~~~~~~ |
| 192 | + |
| 193 | +Please run: |
| 194 | + |
| 195 | +.. code:: shell |
| 196 | +
|
| 197 | + $ python3 manage.py migrate |
| 198 | +
|
| 199 | +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. |
| 200 | + |
| 201 | + |
| 202 | +Create a Django admin user |
| 203 | +~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| 204 | +First you’ll need to create a user who can login to the admin site. Run the following command: |
| 205 | + |
| 206 | +.. code:: shell |
| 207 | +
|
| 208 | + $ python3 manage.py createsuperuser |
| 209 | +
|
| 210 | +which will then produce a prompt which will allow you to create your super user |
| 211 | + |
| 212 | +.. code:: shell |
| 213 | +
|
| 214 | + Username: admin |
| 215 | + Email address: admin@example.com |
| 216 | + Password: ********** |
| 217 | + Password (again): ********** |
| 218 | + Superuser created successfully. |
| 219 | +
|
| 220 | +
|
| 221 | +Login as admin |
| 222 | +~~~~~~~~~~~~~~ |
| 223 | +Now, run the server |
| 224 | + |
| 225 | +.. code:: shell |
| 226 | +
|
| 227 | + python3 manage.py runserver |
| 228 | +
|
| 229 | +Then visit http://127.0.0.1:8000/admin/ |
| 230 | + |
| 231 | +Create and register your first model |
| 232 | +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| 233 | + |
| 234 | +Please follow the guides in https://docs.djangoproject.com/en/4.2/intro/tutorial02/#creating-models |
| 235 | +to create and register the model to the Django’s automatically-generated admin site. |
| 236 | + |
| 237 | +How it works |
| 238 | +------------ |
| 239 | + |
| 240 | +Overall design |
| 241 | +~~~~~~~~~~~~~~ |
| 242 | + |
| 243 | +.. figure:: https://raw.githubusercontent.com/googleapis/google-cloud-python/main/assets/overview.png |
| 244 | + :alt: "Overall Design" |
| 245 | + |
| 246 | +Internals |
| 247 | +~~~~~~~~~ |
| 248 | + |
| 249 | +.. figure:: https://raw.githubusercontent.com/googleapis/google-cloud-python/main/assets/internals.png |
| 250 | + :alt: "Internals" |
| 251 | + |
| 252 | + |
| 253 | +Executing a query |
| 254 | +~~~~~~~~~~~~~~~~~ |
| 255 | + |
| 256 | +Here is an example of how to add a row for Model Author, save it and later query it using Django |
| 257 | + |
| 258 | +.. code:: shell |
| 259 | +
|
| 260 | + >>> author_kent = Author( first_name="Arthur", last_name="Kent", rating=Decimal("4.1"),) |
| 261 | + >>> author_kent.save() |
| 262 | + >>> qs1 = Author.objects.all().values("first_name", "last_name") |
| 263 | +
|
| 264 | +
|
| 265 | +How to contribute |
| 266 | +~~~~~~~~~~~~~~~~~ |
| 267 | + |
| 268 | +Contributions to this library are always welcome and highly encouraged. |
| 269 | + |
| 270 | +See `CONTRIBUTING <https://github.com/googleapis/google-cloud-python/blob/main/CONTRIBUTING.md>`_ for more information on how to get started. |
| 271 | + |
| 272 | +Please note that this project is released with a Contributor Code of Conduct. |
| 273 | +By participating in this project you agree to abide by its terms. See the `Code |
| 274 | +of Conduct <https://github.com/googleapis/google-cloud-python/blob/main/CODE_OF_CONDUCT.md>`_ for more information. |
| 275 | + |
| 276 | + |
| 277 | +Limitations |
| 278 | +~~~~~~~~~~~ |
| 279 | + |
| 280 | +Spanner has certain limitations of its own. The full set of limitations is documented |
| 281 | +`here <https://cloud.google.com/spanner/quotas#schema_limits>`__. |
| 282 | +It is recommended that you go through that list. |
| 283 | + |
| 284 | +Django spanner has a set of limitations as well, which you can find |
| 285 | +`here <https://github.com/googleapis/google-cloud-python/blob/main/docs/limitations.rst>`__. |
| 286 | + |
| 287 | +Features from spanner that are not supported in Django-spanner are listed |
| 288 | +`here <https://github.com/googleapis/google-cloud-python/blob/main/docs/limitations-spanner.rst>`__. |
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