django-extended-choices 1.0.4

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django-extended-choices
=======================

A little application to improve Django choices
----------------------------------------------

``django-extended-choices`` aims to provide a better and more readable
way of using choices_ in Django_.

Installation
------------

You can install directly via pip (since version ``0.3``)::

$ pip install django-extended-choices

Or from the Github_ repository (``master`` branch by default)::

$ git clone git://github.com/twidi/django-extended-choices.git
$ cd django-extended-choices
$ sudo python setup.py install

Usage
-----

The aim is to replace this:

.. code-block:: python

STATE_ONLINE = 1
STATE_DRAFT = 2
STATE_OFFLINE = 3

STATE_CHOICES = (
(STATE_ONLINE, 'Online'),
(STATE_DRAFT, 'Draft'),
(STATE_OFFLINE, 'Offline'),
)

STATE_DICT = dict(STATE_CHOICES)

class Content(models.Model):
title = models.CharField(max_length=255)
content = models.TextField()
state = models.PositiveSmallIntegerField(choices=STATE_CHOICES, default=STATE_DRAFT)

def __unicode__(self):
return u'Content "%s" (state=%s)' % (self.title, STATE_DICT[self.state])

print(Content.objects.filter(state=STATE_ONLINE))

by this:

.. code-block:: python

from extended_choices import Choices

STATES = Choices(
('ONLINE', 1, 'Online'),
('DRAFT', 2, 'Draft'),
('OFFLINE', 3, 'Offline'),
)

class Content(models.Model):
title = models.CharField(max_length=255)
content = models.TextField()
state = models.PositiveSmallIntegerField(choices=STATES, default=STATES.DRAFT)

def __unicode__(self):
return u'Content "%s" (state=%s)' % (self.title, STATES.for_value(self.state).display)

print(Content.objects.filter(state=STATES.ONLINE))


As you can see there is only one declaration for all states with, for each state, in order:

* the pseudo-constant name which can be used (``STATES.ONLINE`` replaces the previous ``STATE_ONLINE``)
* the value to use in the database - which could equally be a string
* the name to be displayed - and you can wrap the text in ``ugettext_lazy()`` if you need i18n

And then, you can use:

* ``STATES``, or ``STATES.choices``, to use with ``choices=`` in fields declarations
* ``STATES.for_constant(constant)``, to get the choice entry from the constant name
* ``STATES.for_value(constant)``, to get the choice entry from the key used in database
* ``STATES.for_display(constant)``, to get the choice entry from the displayable value (can be useful in some case)

Each choice entry obtained by ``for_constant``, ``for_value`` and ``for_display`` return a tuple as
given to the ``Choices`` constructor, but with additional attributes:

.. code-block:: python

>>> entry = STATES.for_constant('ONLINE')
>>> entry == ('ONLINE', 1, 'Online')
True
>>> entry.constant
'ONLINE'
>>> entry.value
1
>>> entry.display
'Online'

These attributes are chainable (with a weird example to see chainability):

.. code-block:: python

>>> entry.constant.value
1
>>> entry.constant.value.value.display.constant.display
'Online'

To allow this, we had to remove support for ``None`` values. Use empty strings instead.

Note that constants can be accessed via a dict key (``STATES['ONLINE']`` for example) if
you want to fight your IDE that may warn you about undefined attributes.


You can check whether a value is in a ``Choices`` object directly:

.. code-block:: python

>>> 1 in STATES
True
>>> 42 in STATES
False


You can even iterate on a ``Choices`` objects to get choices as seen by Django:

.. code-block:: python

>>> for choice in STATES:
... print(choice)
(1, 'Online')
(2, 'Draf')
(3, 'Offline')

To get all choice entries as given to the ``Choices`` object, you can use the ``entries``
attribute:

.. code-block:: python

>>> for choice_entry in STATES.entries:
... print(choice_entry)
('ONLINE', 1, 'Online'),
('DRAFT', 2, 'Draft'),
('OFFLINE', 3, 'Offline'),

Or the following dicts, using constants, values or display names, as keys, and the matching
choice entry as values:

* ``STATES.constants``
* ``STATES.values``
* ``STATES.displays``


.. code-block:: python

>>> STATES.constants['ONLINE'] is STATES.for_constant('ONLINE')
True
>>> STATES.values[2] is STATES.for_value(2)
True
>>> STATES.displays['Offline'] is STATES.for_display('Offline')
True

If you want these dicts to be ordered, you can pass the dict class to use to the
``Choices`` constructor:

.. code-block:: python

from collections import OrderedDict
STATES = Choices(
('ONLINE', 1, 'Online'),
('DRAFT', 2, 'Draft'),
('OFFLINE', 3, 'Offline'),
dict_class = OrderedDict
)

You can check if a constant, value, or display name exists:

.. code-block:: python

>>> STATES.has_constant('ONLINE')
True
>>> STATES.has_value(1)
True
>>> STATES.has_display('Online')
True

You can create subsets of choices within the same ``Choices`` instance:

.. code-block:: python

>>> STATES.add_subset('NOT_ONLINE', ('DRAFT', 'OFFLINE',))
>>> STATES.NOT_ONLINE
(2, 'Draft')
(3, 'Offline')

Now, ``STATES.NOT_ONLINE`` is a real ``Choices`` instance, with a subset of the main ``STATES``
constants.

You can use it to generate choices for when you only want a subset of choices available:

.. code-block:: python

offline_state = models.PositiveSmallIntegerField(
choices=STATES.NOT_ONLINE,
default=STATES.DRAFT
)

As the subset is a real ``Choices`` instance, you have the same attributes and methods:

.. code-block:: python

>>> STATES.NOT_ONLINE.for_constant('OFFLINE').value
3
>>> STATES.NOT_ONLINE.for_value(1).constant
Traceback (most recent call last):
...
KeyError: 3
>>> list(STATES.NOT_ONLINE.constants.keys())
['DRAFT', 'OFFLINE]
>>> STATES.NOT_ONLINE.has_display('Online')
False

You can create as many subsets as you want, reusing the same constants if needed:

.. code-block:: python

STATES.add_subset('NOT_OFFLINE', ('ONLINE', 'DRAFT'))

If you want to check membership in a subset you could do:

.. code-block:: python

def is_online(self):
# it's an example, we could have just tested with STATES.ONLINE
return self.state not in STATES.NOT_ONLINE_DICT

You can add choice entries in many steps using ``add_choices``, possibly creating subsets at
the same time.

To construct the same ``Choices`` as before, we could have done:

.. code-block:: python

STATES = Choices()
STATES.add_choices(
('ONLINE', 1, 'Online)
)
STATES.add_choices(
('DRAFT', 2, 'Draft'),
('OFFLINE', 3, 'Offline'),
name='NOT_ONLINE'
)

You can also pass the ``argument`` to the ``Choices`` constructor to create a subset with all
the choices entries added at the same time (it will call ``add_choices`` with the name and the
entries)

Notes
-----

* You also have a very basic field (``NamedExtendedChoiceFormField```) in ``extended_choices.fields`` which accept constant names instead of values
* Feel free to read the source to learn more about this little Django app.
* You can declare your choices where you want. My usage is in the ``models.py`` file, just before the class declaration.

Compatibility
-------------

The version ``1.0`` provides a totally new API, but stays fully compatible with the previous one
(``0.4.1``). So it adds a lot of attributes in each ``Choices`` instance:

* ``CHOICES``
* ``CHOICES_DICT``
* ``REVERTED_CHOICES_DICT``
* ``CHOICES_CONST_DICT``

(And 4 more for each subset)

If you don't want it, simply set the argument ``retro_compatibility`` to ``False`` when creating
a ``Choices`` instance:

.. code-block:: python

STATES = Choices(
('ONLINE', 1, 'Online'),
('DRAFT', 2, 'Draft'),
('OFFLINE', 3, 'Offline'),
retro_compatibility=False
)

This flag is currently ``True`` by default, and it will not be changed for at least 6 months
counting from the publication of this version ``1.0`` (``1st of May, 2015``, so until the
``1st of November, 2015``, AT LEAST, the compatibility will be on by default).

Then, the flag will stay but will be off by default. To keep compatibility, you'll have to
pass the ``retro_compatibility`` argument and set it to ``True``.

Then, after another period of 6 months minimum, the flag and all the retro_compatibility code
will be removed (so not before ``1st of May, 2016``).

Note that you can use a specific version by pinning it in your requirements.

The only exception to these rules, it's the support of Django ``1.4`` that was removed in version
``1.0.3`` due to some incompatibility problems with ``ugettext_lazy``.

Also, the support of ``None`` values was removed, raising a ``ValueError`` telling the user to
instead use an empty string.


License
-------

Available under the BSD_ License. See the ``LICENSE`` file included

Python 3?
---------

Of course! We support python ``2.6``, ``2.7``, ``3.3`` and `3.4`, for Django version ``1.5.x`` to
``1.8.x``, respecting the `Django matrix`_ (except for python ``2.5`` and ``3.2`` which are not
supported by ``django-extended-choices``)


Tests
-----

To run tests from the code source, create a virtualenv or activate one, install Django, then::

python -m extended_choices.tests


We also provides some quick doctests in the code documentation. To execute them::

python -m extended_choices.choices


Source code
-----------

The source code is available on Github_.


Developing
----------

If you want to participate in the development of this library, you'll need ``Django``
installed in your virtualenv. If you don't have it, simply run::

pip install -r requirements-dev.txt

Don't forget to run the tests ;)

Feel free to propose a pull request on Github_!

A few minutes after your pull request, tests will be executed on TravisCi_ for all the versions
of python and Django we support.


Documentation
-------------

You can find the documentation on ReadTheDoc_

To update the documentation, you'll need some tools::

pip install -r requirements-makedoc.txt

Then go to the ``docs`` directory, and run::

make html

Author
------
Written by Stephane "Twidi" Angel <s.angel@twidi.com> (http://twidi.com), originally for http://www.liberation.fr

.. _choices: http://docs.djangoproject.com/en/1.5/ref/models/fields/#choices
.. _Django: http://www.djangoproject.com/
.. _Github: https://github.com/twidi/django-extended-choices
.. _Django matrix: https://docs.djangoproject.com/en/1.8/faq/install/#what-python-version-can-i-use-with-django
.. _TravisCi: https://travis-ci.org/twidi/django-extended-choices/pull_requests
.. _RedTheDoc: http://django-extended-choices.readthedocs.org
.. _BSD: http://opensource.org/licenses/BSD-3-Clause

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