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Constance - Dynamic Django settings
===================================
Features
--------
* Easily migrate your static settings to dynamic settings.
* Edit the dynamic settings in the Django admin interface.
.. image:: _static/screenshot2.png
Quick Installation
------------------
.. code-block::
pip install "django-constance[redis]"
For complete installation instructions, including how to install the
database backend, see :ref:`Backends <backends>`.
Configuration
-------------
Modify your ``settings.py``. Add ``'constance'`` to your
:setting:`INSTALLED_APPS`, and move each key you want to turn dynamic into
the :setting:`CONSTANCE_CONFIG` section, like this:
.. code-block:: python
INSTALLED_APPS = (
'django.contrib.admin',
'django.contrib.staticfiles',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
...
'constance',
)
CONSTANCE_CONFIG = {
'THE_ANSWER': (42, 'Answer to the Ultimate Question of Life, '
'The Universe, and Everything'),
}
.. note:: Add constance *before* your project apps.
.. note:: If you use admin extensions like
`Grapelli <https://grappelliproject.com/>`_, ``'constance'`` should be added
in :setting:`INSTALLED_APPS` *before* those extensions.
Here, ``42`` is the default value for the key ``THE_ANSWER`` if it is
not found in the backend. The other member of the tuple is a help text the
admin will show.
See the :ref:`Backends <backends>` section how to setup the backend and
finish the configuration.
``django-constance``'s hashes generated in different instances of the same
application may differ, preventing data from being saved.
Use :setting:`CONSTANCE_IGNORE_ADMIN_VERSION_CHECK` in order to skip hash
verification.
.. code-block:: python
CONSTANCE_IGNORE_ADMIN_VERSION_CHECK = True
Signals
-------
Each time a value is changed it will trigger a ``config_updated`` signal.
.. code-block:: python
from constance.signals import config_updated
@receiver(config_updated)
def constance_updated(sender, key, old_value, new_value, **kwargs):
print(sender, key, old_value, new_value)
The sender is the ``config`` object, and the ``key`` and ``new_value``
are the changed settings.
Custom fields
-------------
You can set the field type with the third value in the ``CONSTANCE_CONFIG`` tuple.
The value can be one of the supported types or a string matching a key in your :setting:``CONSTANCE_ADDITIONAL_FIELDS``
The supported types are:
* ``bool``
* ``int``
* ``float``
* ``Decimal``
* ``str``
* ``datetime``
* ``timedelta``
* ``date``
* ``time``
* ``list``
* ``dict``
For example, to force a value to be handled as a string:
.. code-block:: python
'THE_ANSWER': (42, 'Answer to the Ultimate Question of Life, '
'The Universe, and Everything', str),
Custom field types are supported using the dictionary :setting:``CONSTANCE_ADDITIONAL_FIELDS``.
This is a mapping between a field label and a sequence (list or tuple). The first item in the sequence is the string
path of a field class, and the (optional) second item is a dictionary used to configure the field.
The ``widget`` and ``widget_kwargs`` keys in the field config dictionary can be used to configure the widget used in admin,
the other values will be passed as kwargs to the field's ``__init__()``
.. note:: Use later evaluated strings instead of direct classes for the field and widget classes:
.. code-block:: python
CONSTANCE_ADDITIONAL_FIELDS = {
'yes_no_null_select': ['django.forms.fields.ChoiceField', {
'widget': 'django.forms.Select',
'choices': ((None, "-----"), ("yes", "Yes"), ("no", "No"))
}],
}
CONSTANCE_CONFIG = {
'MY_SELECT_KEY': ('yes', 'select yes or no', 'yes_no_null_select'),
}
If you want to work with images or files you can use this configuration:
.. code-block:: python
CONSTANCE_ADDITIONAL_FIELDS = {
'image_field': ['django.forms.ImageField', {}]
}
CONSTANCE_CONFIG = {
'LOGO_IMAGE': ('default.png', 'Company logo', 'image_field'),
}
When used in a template you probably need to use:
.. code-block:: html
{% load static %}
{% get_media_prefix as MEDIA_URL %}
<img src="{{ MEDIA_URL }}{{ config.LOGO_IMAGE }}">
Images and files are uploaded to ``MEDIA_ROOT`` by default. You can specify a subdirectory of ``MEDIA_ROOT`` to use instead by adding the ``CONSTANCE_FILE_ROOT`` setting. E.g.:
.. code-block:: python
MEDIA_ROOT = os.path.join(BASE_DIR, 'media')
CONSTANCE_FILE_ROOT = 'constance'
This will result in files being placed in ``media/constance`` within your ``BASE_DIR``. You can use deeper nesting in this setting (e.g. ``constance/images``) but other relative path components (e.g. ``../``) will be rejected.
Ordered Fields in Django Admin
------------------------------
To sort the fields, you can use an OrderedDict:
.. code-block:: python
from collections import OrderedDict
CONSTANCE_CONFIG = OrderedDict([
('SITE_NAME', ('My Title', 'Website title')),
('SITE_DESCRIPTION', ('', 'Website description')),
('THEME', ('light-blue', 'Website theme')),
])
Fieldsets
---------
You can define fieldsets to group settings together:
.. code-block:: python
CONSTANCE_CONFIG = {
'SITE_NAME': ('My Title', 'Website title'),
'SITE_DESCRIPTION': ('', 'Website description'),
'THEME': ('light-blue', 'Website theme'),
}
CONSTANCE_CONFIG_FIELDSETS = {
'General Options': ('SITE_NAME', 'SITE_DESCRIPTION'),
'Theme Options': ('THEME',),
}
.. note:: CONSTANCE_CONFIG_FIELDSETS must contain all fields from CONSTANCE_CONFIG.
.. image:: _static/screenshot3.png
Fieldsets collapsing
--------------------
To make some fieldsets collapsing you can use new format in CONSTANCE_CONFIG_FIELDSETS. Here's an example:
.. code-block:: python
CONSTANCE_CONFIG = {
'SITE_NAME': ('My Title', 'Website title'),
'SITE_DESCRIPTION': ('', 'Website description'),
'THEME': ('light-blue', 'Website theme'),
}
CONSTANCE_CONFIG_FIELDSETS = {
'General Options': {
'fields': ('SITE_NAME', 'SITE_DESCRIPTION'),
'collapse': True
},
'Theme Options': ('THEME',),
}
Field internationalization
--------------------------
Field description and fieldset headers can be integrated into Django's
internationalization using the ``gettext_lazy`` function. Note that the
``CONSTANCE_CONFIG_FIELDSETS`` must be converted to a tuple instead of dict
as it is not possible to have lazy proxy objects as dictionary keys in the
settings file. Example:
.. code-block:: python
from django.utils.translation import gettext_lazy as _
CONSTANCE_CONFIG = {
'SITE_NAME': ('My Title', _('Website title')),
'SITE_DESCRIPTION': ('', _('Website description')),
'THEME': ('light-blue', _('Website theme')),
}
CONSTANCE_CONFIG_FIELDSETS = (
(
_('General Options'),
{
'fields': ('SITE_NAME', 'SITE_DESCRIPTION'),
'collapse': True,
},
),
(_('Theme Options'), ('THEME',)),
)
Usage
-----
Constance can be used from your Python code and from your Django templates.
Python
^^^^^^
Accessing the config variables is as easy as importing the config
object and accessing the variables with attribute lookups::
from constance import config
# ...
if config.THE_ANSWER == 42:
answer_the_question()
Django templates
^^^^^^^^^^^^^^^^
To access the config object from your template you can
pass the object to the template context:
.. code-block:: python
from django.shortcuts import render
from constance import config
def myview(request):
return render(request, 'my_template.html', {'config': config})
You can also use the included context processor.
Insert ``'constance.context_processors.config'`` at
the top of your ``TEMPLATES['OPTIONS']['context_processors']`` list. See the
`Django documentation`_ for details.
.. _`Django documentation`: https://docs.djangoproject.com/en/1.11/ref/templates/upgrading/#the-templates-settings
This will add the config instance to the context of any template
rendered with a ``RequestContext``.
Then, in your template you can refer to the config values just as
any other variable, e.g.:
.. code-block:: django
<h1>Welcome on {{ config.SITE_NAME }}</h1>
{% if config.BETA_LAUNCHED %}
Woohoo! Head over <a href="/sekrit/">here</a> to use the beta.
{% else %}
Sadly we haven't launched yet, click <a href="/newsletter/">here</a>
to signup for our newsletter.
{% endif %}
Command Line
^^^^^^^^^^^^
Constance settings can be get/set on the command line with the manage command :command:`constance`.
Available options are:
.. program:: constance
.. option:: list
list all Constance keys and their values
.. code-block:: console
$ ./manage.py constance list
THE_ANSWER 42
SITE_NAME My Title
.. option:: get <KEY>
get the value of a Constance key
.. code-block:: console
$ ./manage.py constance get THE_ANSWER
42
.. option:: set <KEY> <VALUE>
set the value of a Constance key
.. code-block:: console
$ ./manage.py constance set SITE_NAME "Another Title"
If the value contains spaces it should be wrapped in quotes.
.. note:: Set values are validated as per in admin, an error will be raised if validation fails:
E.g., given this config as per the example app:
.. code-block:: python
CONSTANCE_CONFIG = {
...
'DATE_ESTABLISHED': (date(1972, 11, 30), "the shop's first opening"),
}
Setting an invalid date will fail as follow:
.. code-block:: console
$ ./manage.py constance set DATE_ESTABLISHED '1999-12-00'
CommandError: Enter a valid date.
.. note:: If the admin field is a :class:`MultiValueField`, then the separate field values need to be provided as separate arguments.
E.g., a datetime using :class:`SplitDateTimeField`:
.. code-block:: python
CONSTANCE_CONFIG = {
'DATETIME_VALUE': (datetime(2010, 8, 23, 11, 29, 24), 'time of the first commit'),
}
Then this works (and the quotes are optional):
.. code-block:: console
./manage.py constance set DATETIME_VALUE '2011-09-24' '12:30:25'
This doesn't work:
.. code-block:: console
./manage.py constance set DATETIME_VALUE '2011-09-24 12:30:25'
CommandError: Enter a list of values.
.. option:: remove_stale_keys
delete all Constance keys and their values if they are not in settings.CONSTANCE_CONFIG (stale keys)
.. code-block:: console
$ ./manage.py constance remove_stale_keys
Record is considered stale if it exists in database but absent in config.
Editing
-------
Fire up your ``admin`` and you should see a new app called ``Constance``
with ``THE_ANSWER`` in the ``Config`` pseudo model.
By default, changing the settings via the admin is only allowed for superusers.
To change this, feel free to set the :setting:`CONSTANCE_SUPERUSER_ONLY`
setting to ``False`` and give users or user groups access to the
``constance.change_config`` permission.
.. figure:: _static/screenshot1.png
The virtual application ``Constance`` among your regular applications.
Custom settings form
--------------------
If you aim at creating a custom settings form this is possible in the following
way: You can inherit from ``ConstanceAdmin`` and set the ``form`` property on
your custom admin to use your custom form. This allows you to define your own
formsets and layouts, similar to defining a custom form on a standard
Django ModelAdmin. This way you can fully style your settings form and group
settings the way you like.
.. code-block:: python
from constance.admin import ConstanceAdmin, Config
from constance.forms import ConstanceForm
class CustomConfigForm(ConstanceForm):
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
#... do stuff to make your settings form nice ...
class ConfigAdmin(ConstanceAdmin):
change_list_form = CustomConfigForm
change_list_template = 'admin/config/settings.html'
admin.site.unregister([Config])
admin.site.register([Config], ConfigAdmin)
You can also override the ``get_changelist_form`` method which is called in
``changelist_view`` to get the actual form used to change the settings. This
allows you to pick a different form according to the user that makes the
request. For example:
.. code-block:: python
class SuperuserForm(ConstanceForm):
# Do some stuff here
class MyConstanceAdmin(ConstanceAdmin):
def get_changelist_form(self, request):
if request.user.is_superuser:
return SuperuserForm:
else:
return super().get_changelist_form(request)
Note that the default method returns ``self.change_list_form``.
More documentation
------------------
.. toctree::
:maxdepth: 2
backends
testing
changes
Indices and tables
==================
* :ref:`genindex`
* :ref:`modindex`
* :ref:`search`
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