django-extended-choices 0.3.0

Little helper application to improve django choices(for fields)

django-extended-choices aims to provide a better (ie for me) 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

And add this line to your settings.py

Usage

The aim is to replace this:

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 ContentModel(models.Model):
    title      = models.CharField(max_length=255)
    content    = models.TextField()
    state      = models.PositiveSmallIntegerField(choices=STATE_CHOICES, default=STATE_DRAFT)
    related_to = models.ManyToManyField('self', through="ContentToContent", symmetrical=False, blank=True, null=True)

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

    def get_related_content(self):
        return self.related_to.select_related().filter(state=STATE_ONLINE)

by this

from extended_choices import Choices

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

class ContentModel(models.Model):
    title      = models.CharField(max_length=255)
    content    = models.TextField()
    state      = models.PositiveSmallIntegerField(choices=STATES.CHOICES, default=STATES.DRAFT)
    related_to = models.ManyToManyField('self', through="ContentToContent", symmetrical=False, blank=True, null=True)

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

    def get_related_content(self):
        return self.related_to.select_related().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 as key in database

• the name to be displayed

And then, you can use:

• STATES.CHOICES, to use with choices= in fields declarations

• STATES.CHOICES_DICT, a dict to get the value to display with the key used in database

• STATES.REVERTED_CHOICES_DICT, a dict to get the key from the displayable value (can be useful in some case)

• STATES.CHOICES_CONST_DICT, a dict to get value from constant name

• STTES.REVERTED_CHOICES_CONST_DICT, a dict to get constant name from value

You can create subsets of choices within the sane variable:

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

STATES.add_subset('NOT_ONLINE', ('DRAFT', 'OFFILNE',))

Now, STATES.NOT_ONLINE is a full Choices object, with a subset of the main STATES choices. You can use it in a filter:

def is_online(self):
    # it's an example, we could have test STATES.ONLINE
    return self.state not in STATES.NOT_ONLINE

not in ? Yes, you can use in and even iterate on Choices objects !

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.

Future

• Next version (1.0 ?) will NOT be compatible with 0.X ones, because all the names (*_DICT) will be renamed to be easier to memorize (using names “ala” as_dict…)

License

Licensed under the General Public License (GPL). See the License file included

Source code

The source code is available on github

Author

Written by Stephane “Twidi” Angel <[e-mail]> (http://twidi.com), originally for http://www.liberation.fr