=================
Advanced features
=================

.. _caching:

Caching
=======

``dbtemplates`` uses Django's default caching infrastructure for caching, and
operates automatically when creating, updating or deleting templates in
the database.

To enable one of them you need to specify a setting called
``DBTEMPLATES_CACHE_BACKEND`` to one of the valid values Django's
``CACHE_BACKEND`` can be set to. E.g.::

    DBTEMPLATES_CACHE_BACKEND = 'memcached://127.0.0.1:11211/'

.. note::
    Starting in version 1.0 ``dbtemplates`` allows you also to set the new
    dict-based ``CACHES`` setting, which was introduced in Django 1.3.

    All you have to do is to provide a new entry in the ``CACHES`` dict
    named ``'dbtemplates'``, e.g.::

        CACHES = {
            'dbtemplates': {
                'BACKEND': 'django.core.cache.backends.memcached.MemcachedCache',
                'LOCATION': '127.0.0.1:11211',
            }
        }

Please see the `cache documentation`_ if you want to know more about it.

.. _cache documentation: http://docs.djangoproject.com/en/dev/topics/cache/#setting-up-the-cache

.. _versioned:

Versioned storage
=================

``dbtemplates`` comes prepared to use the third party Django app
`django-reversion`_, that once installed besides ``dbtemplates`` allows you
to jump back to old versions of your templates. It automatically saves every
state when you save the template in your database and provides an easy to use
interface.

Please refer to `django-reversion's documentation`_ for more information
about how it works.

.. hint::
    Just visit the "History" section of each template instance and browse its history.

Short installation howto
------------------------

1. Get the source from the `django-reversion`_ project site and put it
   somewhere on your `PYTHONPATH`.
2. Add ``reversion`` to the ``INSTALLED_APPS`` setting of your Django project
3. Sync your database with ``python manage.py syncdb``
4. Set ``DBTEMPLATES_USE_REVERSION`` setting to ``True``

History compare view
--------------------

You can also use ``dbtemplates`` together with `django-reversion-compare`_ which
provides a history compare view to compare two versions of a model which is under
reversion.

.. _django-reversion: https://github.com/etianen/django-reversion
.. _django-reversion's documentation: https://django-reversion.readthedocs.io/en/latest/
.. _django-reversion-compare: https://github.com/jedie/django-reversion-compare


.. _commands:

Management commands
===================

``dbtemplates`` comes with two `Django management commands`_ to be used with
``django-admin.py`` or ``manage.py``:

* ``sync_templates``

  Enables you to sync your already existing file systems templates with the
  database. It will guide you through the whole process.

* ``create_error_templates``

  Tries to add the two templates ``404.html`` and ``500.html`` that are used
  by Django when a error occurs.

* ``check_template_syntax``

  .. versionadded:: 1.2

  Checks the saved templates whether they are valid Django templates.

.. _Django management commands: http://docs.djangoproject.com/en/dev/ref/django-admin/

.. _admin_actions:

Admin actions
=============

``dbtemplates`` provides two `admin actions`_ to be used with Django>=1.1.

* ``invalidate_cache``

  Invalidates the cache of the selected templates by calling the appropriate
  cache backend methods.

* ``repopulate_cache``

  Repopulates the cache with selected templates by invalidating it first and
  filling then after that.

* ``check_syntax``

  .. versionadded:: 1.2

  Checks the selected tempaltes for syntax errors.

.. _admin actions: http://docs.djangoproject.com/en/dev/ref/contrib/admin/actions/