root/django/branches/0.90-bugfixes/docs/legacy_databases.txt

==================================
Integrating with a legacy database
==================================

While Django is best suited for developing new applications, it's quite
possible to integrate it into legacy databases. Django includes a couple of
utilities to automate as much of this process as possible.

This document assumes you know the Django basics, as covered in the
`official tutorial`_.

.. _official tutorial: http://www.djangoproject.com/documentation/tutorial1/

Give Django your database parameters
====================================

You'll need to tell Django what your database connection parameters are, and
what the name of the database is. Do that by editing these settings in your
`settings file`_:

    * `DATABASE_ENGINE`_
    * `DATABASE_USER`_
    * `DATABASE_PASSWORD`_
    * `DATABASE_NAME`_
    * `DATABASE_HOST`_
    * `DATABASE_PORT`_

.. _settings file: http://www.djangoproject.com/documentation/settings/
.. _DATABASE_ENGINE: http://www.djangoproject.com/documentation/settings/#database-engine
.. _DATABASE_USER: http://www.djangoproject.com/documentation/settings/#database-user
.. _DATABASE_PASSWORD: http://www.djangoproject.com/documentation/settings/#database-password
.. _DATABASE_NAME: http://www.djangoproject.com/documentation/settings/#database-name
.. _DATABASE_HOST: http://www.djangoproject.com/documentation/settings/#database-host
.. _DATABASE_PORT: http://www.djangoproject.com/documentation/settings/#database-port

Auto-generate the models
========================

Django comes with a utility that can create models by introspecting an existing
database. You can view the output by running this command::

    django-admin.py inspectdb [databasename] --settings=path.to.settings

...where "[databasename]" is the name of your database.

Save this as a file by using standard Unix output redirection::

    django-admin.py inspectdb [databasename] --settings=path.to.settings > appname.py

This feature is meant as a shortcut, not as definitive model generation. See
the `django-admin.py documentation`_ for more information.

Once you've cleaned up the model, put the module in the ``models`` directory of
your app, and add it to your ``INSTALLED_APPS`` setting.

.. _django-admin.py documentation: http://www.djangoproject.com/documentation/django_admin/

Install the core Django tables
==============================

Next, run the ``django-admin.py init`` command to install Django's core tables
in your database::

    django-admin.py init --settings=path.to.settings

This won't work if your database already contains tables that have any of the
following names:

    * ``sites``
    * ``packages``
    * ``content_types``
    * ``core_sessions``
    * ``auth_permissions``
    * ``auth_groups``
    * ``auth_users``
    * ``auth_messages``
    * ``auth_groups_permissions``
    * ``auth_users_groups``
    * ``auth_users_user_permissions``

If that's the case, try renaming one of your tables to resolve naming
conflicts. Currently, there's no way of customizing the names of Django's
database tables without editing Django's source code itself.

Install metadata about your app
===============================

Django has a couple of database tables that contain metadata about your apps.
You'll need to execute the SQL output by this command::

    django-admin.py sqlinitialdata [appname] --settings=path.to.settings

See whether it worked
=====================

That's it. Try accessing your data via the Django database API, and try editing
objects via Django's admin site.