Welcome to django-extended-choices’s documentation!

What is it?

Little helper application to improve django choices (for fields)

Documentation contents

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:

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:

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:

>>> 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):

>>> 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:

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

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

>>> 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:

>>> 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

>>> 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:

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

Since version 1.1, the new OrderedChoices``class is provided, that is exactly that: a ``Choices using OrderedDict by default for dict_class. You can directly import it from extended_choices.

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

>>> 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:

>>> 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:

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:

>>> 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:

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

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

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:

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)

The list of existing subset names is in the subsets attributes of the parent Choices object.

If you want a subset of the choices but not save it in the original Choices object, you can use extract_subset instead of add_subset

>>> subset = STATES.extract_subset('DRAFT', 'OFFLINE')
>>> subset
(2, 'Draft')
(3, 'Offline')

As for a subset created by add_subset, you have a real Choices object, but not accessible from the original Choices object.

Note that in extract_subset, you pass the strings directly, not in a list/tuple as for the second argument of add_subset.

Additional attributes

Each tuple must contain three elements. But you can pass a dict as a fourth one and each entry of this dict will be saved as an attribute of the choice entry

>>> PLANETS = Choices(
...     ('EARTH', 'earth', 'Earth', {'color': 'blue'}),
...     ('MARS', 'mars', 'Mars', {'color': 'red'}),
... )
>>> PLANETS.EARTH.color
'blue'

Auto display/value

We provide two classes to eases the writing of your choices, attended you don’t need translation on the display value.

AutoChoices

It’s the simpler and faster version: you just past constants and:

• the value saved in database will be constant lower cased
• the display value will be the constant with _ replaced by spaces, and the first letter capitalized

>>> from extended_choices import AutoChoices
>>> PLANETS = AutoChoices('EARTH', 'MARS')
>>> PLANETS.EARTH.value
'earth'
>>> PLANETS.MARS.display
'Mars'

If you want to pass additional attributes, pass a tuple with the dict as a last element:

>>> PLANETS = AutoChoices(
...     ('EARTH', {'color': 'blue'}),
...     ('MARS', {'color': 'red'}),
... )
>>> PLANETS.EARTH.value
'earth'
>>> PLANETS.EARTH.color
'blue'

You can change the transform function used to convert the constant to the value to be saved and the display value, by passing value_transform and display_transform functions to the constructor.

>>> PLANETS = AutoChoices(
...     'EARTH', 'MARS',
...     value_transform=lambda const: 'planet_' + const.lower().
...     display_transform=lambda const: 'Planet: ' + const.lower().
... )
>>> PLANETS.EARTH.value
'planet_earth'
>>> PLANETS.MARS.display
'Planet: mars'

If you find yourself repeting these transform functions you can have a base class that defines these function, as class attributes:

>>> class MyAutoChoices(AutoChoices):
...     value_transform=staticmethod(lambda const: const.upper())
...     display_transform=staticmethod(lambda const: const.lower())

>>> PLANETS = MyAutoChoices('EARTH', 'MARS')
>>> PLANETS.EARTH.value
'EARTH'
>>> PLANETS.MARS.dispay
'mars'

Of course you can still override the functions by passing them to the constructor.

If you want, for an entry, force a specific value, you can do it by simply passing it as a second argument:

>>> PLANETS = AutoChoices(
...     'EARTH',
...     ('MARS', 'red-planet'),
... )
>>> PLANETS.MARS.value
'red-planet'

And then if you want to set the display, pass a third one:

>>> PLANETS = AutoChoices(
...     'EARTH',
...     ('MARS', 'red-planet', 'Red planet'),
... )
>>> PLANETS.MARS.value
'red-planet'
>>> PLANETS.MARS.display
'Red planet'

To force a display value but let the db value to be automatically computed, use None for the second argument:

>>> PLANETS = AutoChoices(
...     'EARTH',
...     ('MARS', None, 'Red planet'),
... )
>>> PLANETS.MARS.value
'mars'
>>> PLANETS.MARS.display
'Red planet'

AutoDisplayChoices

In this version, you have to define the value to save in database. The display value will be composed like in AutoChoices

>>> from extended_choices import AutoDisplayChoices
>>> PLANETS = AutoDisplayChoices(
...     ('EARTH', 1),
...     ('MARS', 2),
... )
>>> PLANETS.EARTH.value
1
>>> PLANETS.MARS.display
'Mars'

If you want to pass additional attributes, pass a tuple with the dict as a last element:

>>> PLANETS = AutoDisplayChoices(
...     ('EARTH', 'earth', {'color': 'blue'}),
...     ('MARS', 'mars', {'color': 'red'}),
... )
>>> PLANETS.EARTH.value
1
>>> PLANETS.EARTH.display
'Earth'
>>> PLANETS.EARTH.color
'blue'

As in AutoChoices, you can change the transform function for the value to display by passing display_transform to the constructor.

If you want, for an entry, force a specific display, you can do it by simply passing it as a third argument:

>>> PLANETS = AutoChoices(
...     ('EARTH', 1),
...     ('MARS', 2, 'Red planet'),
... )
>>> PLANETS.MARS.display
'Red planet'

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 provided a totally new API, and compatibility with the previous one (0.4.1) was removed in 1.1. The last version with the compatibility was 1.0.7.

If you need this compatibility, you can use a specific version by pinning it in your requirements.

License

Available under the BSD License. See the LICENSE file included

Python/Django versions support

Django version	Python versions
1.8	2.7, 3.4, 3.5
1.9, 1.10	2.7, 3.4, 3.5
1.11	2.7, 3.4, 3.5, 3.6
2.0	3.4, 3.5, 3.6
2.1	3.5, 3.6, 3.7

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

Note: the doctests will work only in python version not display u prefix for strings.

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

extended_choices.choices module

Provides a Choices class to help using “choices” in Django fields.

The aim is to replace:

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 'Content "%s" (state=%s)' % (self.title, STATE_DICT[self.state])

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

By this:

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 'Content "%s" (state=%s)' % (self.title, STATES.for_value(self.state).display)

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

Notes

The documentation format in this file is numpydoc.

class extended_choices.choices.Choices(*choices, **kwargs)

Bases: list

Helper class for choices fields in Django

A choice entry has three representation: constant name, value and display name). So Choices takes list of such tuples.

It’s easy to get the constant, value or display name given one of these value. See in example.

Parameters:

• *choices (list of tuples) –

  It’s the list of tuples to add to the Choices instance, each tuple having three entries: the constant name, the value, the display name.

  A dict could be added as a 4th entry in the tuple to allow setting arbitrary arguments to the final ChoiceEntry created for this choice tuple.

• name (string, optional) – If set, a subset will be created containing all the constants. It could be used if you construct your Choices instance with many calls to add_choices.
• dict_class (type, optional) – dict by default, it’s the dict class to use to create dictionaries (constants, values and displays. Could be set for example to OrderedDict (you can use OrderedChoices that is a simple subclass using OrderedDict.

Example

Start by declaring your Choices:

>>> ALIGNMENTS = Choices(
...     ('BAD', 10, 'bad'),
...     ('NEUTRAL', 20, 'neutral'),
...     ('CHAOTIC_GOOD', 30, 'chaotic good'),
...     ('GOOD', 40, 'good'),
...     dict_class=OrderedDict
... )

Then you can use it in a django field, Notice its usage in choices and default:

>>> from django.conf import settings
>>> try:
...     settings.configure(DATABASE_ENGINE='sqlite3')
... except: pass
>>> from django.db.models import IntegerField
>>> field = IntegerField(choices=ALIGNMENTS,  # use ``ALIGNMENTS`` or ``ALIGNMENTS.choices``.
...                      default=ALIGNMENTS.NEUTRAL)

The Choices returns a list as expected by django:

>>> ALIGNMENTS == ((10, 'bad'), (20, 'neutral'), (30, 'chaotic good'), (40, 'good'))
True

But represents it with the constants:

>>> repr(ALIGNMENTS)
"[('BAD', 10, 'bad'), ('NEUTRAL', 20, 'neutral'), ('CHAOTIC_GOOD', 30, 'chaotic good'), ('GOOD', 40, 'good')]"

Use choices which is a simple list to represent it as such:

>>> ALIGNMENTS.choices
((10, 'bad'), (20, 'neutral'), (30, 'chaotic good'), (40, 'good'))

And you can access value by their constant, or as you want:

>>> ALIGNMENTS.BAD
10
>>> ALIGNMENTS.BAD.display
'bad'
>>> 40 in ALIGNMENTS
True
>>> ALIGNMENTS.has_constant('BAD')
True
>>> ALIGNMENTS.has_value(20)
True
>>> ALIGNMENTS.has_display('good')
True
>>> ALIGNMENTS.for_value(10)
('BAD', 10, 'bad')
>>> ALIGNMENTS.for_value(10).constant
'BAD'
>>> ALIGNMENTS.for_display('good').value
40
>>> ALIGNMENTS.for_constant('NEUTRAL').display
'neutral'
>>> ALIGNMENTS.constants
OrderedDict([('BAD', ('BAD', 10, 'bad')), ('NEUTRAL', ('NEUTRAL', 20, 'neutral')), ('CHAOTIC_GOOD', ('CHAOTIC_GOOD', 30, 'chaotic good')), ('GOOD', ('GOOD', 40, 'good'))])
>>> ALIGNMENTS.values
OrderedDict([(10, ('BAD', 10, 'bad')), (20, ('NEUTRAL', 20, 'neutral')), (30, ('CHAOTIC_GOOD', 30, 'chaotic good')), (40, ('GOOD', 40, 'good'))])
>>> ALIGNMENTS.displays
OrderedDict([('bad', ('BAD', 10, 'bad')), ('neutral', ('NEUTRAL', 20, 'neutral')), ('chaotic good', ('CHAOTIC_GOOD', 30, 'chaotic good')), ('good', ('GOOD', 40, 'good'))])

You can create subsets of choices:

>>> ALIGNMENTS.add_subset('WESTERN',('BAD', 'GOOD'))
>>> ALIGNMENTS.WESTERN.choices
((10, 'bad'), (40, 'good'))
>>> ALIGNMENTS.BAD in ALIGNMENTS.WESTERN
True
>>> ALIGNMENTS.NEUTRAL in ALIGNMENTS.WESTERN
False

To use it in another field (only the values in the subset will be available), or for checks:

>>> def is_western(value):
...     return value in ALIGNMENTS.WESTERN
>>> is_western(40)
True

ChoiceEntryClass

alias of extended_choices.helpers.ChoiceEntry

add_choices(*choices, **kwargs)

Add some choices to the current Choices instance.

The given choices will be added to the existing choices. If a name attribute is passed, a new subset will be created with all the given choices.

Note that it’s not possible to add new choices to a subset.

Parameters:

• *choices (list of tuples) –

  It’s the list of tuples to add to the Choices instance, each tuple having three entries: the constant name, the value, the display name.

  A dict could be added as a 4th entry in the tuple to allow setting arbitrary arguments to the final ChoiceEntry created for this choice tuple.

  If the first entry of *choices is a string, then it will be used as a name for a new subset that will contain all the given choices.

• **kwargs (dict) –

  name : string

  Instead of using the first entry of the *choices to pass a name of a subset to create, you can pass it via the name named argument.

Example

>>> MY_CHOICES = Choices()
>>> MY_CHOICES.add_choices(('ZERO', 0, 'zero'))
>>> MY_CHOICES
[('ZERO', 0, 'zero')]
>>> MY_CHOICES.add_choices('SMALL', ('ONE', 1, 'one'), ('TWO', 2, 'two'))
>>> MY_CHOICES
[('ZERO', 0, 'zero'), ('ONE', 1, 'one'), ('TWO', 2, 'two')]
>>> MY_CHOICES.SMALL
[('ONE', 1, 'one'), ('TWO', 2, 'two')]
>>> MY_CHOICES.add_choices(('THREE', 3, 'three'), ('FOUR', 4, 'four'), name='BIG')
>>> MY_CHOICES
[('ZERO', 0, 'zero'), ('ONE', 1, 'one'), ('TWO', 2, 'two'), ('THREE', 3, 'three'), ('FOUR', 4, 'four')]
>>> MY_CHOICES.BIG
[('THREE', 3, 'three'), ('FOUR', 4, 'four')]

Raises:

• RuntimeError – When the Choices instance is marked as not mutable, which is the case for subsets.
• ValueError –
  • if the subset name is defined as first argument and as named argument. * if some constants have the same name or the same value. * if at least one constant or value already exists in the instance.

add_subset(name, constants)

Add a subset of entries under a defined name.

This allow to defined a “sub choice” if a django field need to not have the whole choice available.

The sub-choice is a new Choices instance, with only the wanted the constant from the main Choices (each “choice entry” in the subset is shared from the main Choices) The sub-choice is accessible from the main Choices by an attribute having the given name.

Parameters:

• name (string) – Name of the attribute that will old the new Choices instance.
• constants (list or tuple) – List of the constants name of this Choices object to make available in the subset.

Returns:

The newly created subset, which is a Choices object

Return type:

Choices

Example

>>> STATES = Choices(
...     ('ONLINE',  1, 'Online'),
...     ('DRAFT',   2, 'Draft'),
...     ('OFFLINE', 3, 'Offline'),
... )
>>> STATES
[('ONLINE', 1, 'Online'), ('DRAFT', 2, 'Draft'), ('OFFLINE', 3, 'Offline')]
>>> STATES.add_subset('NOT_ONLINE', ('DRAFT', 'OFFLINE',))
>>> STATES.NOT_ONLINE
[('DRAFT', 2, 'Draft'), ('OFFLINE', 3, 'Offline')]
>>> STATES.NOT_ONLINE.DRAFT
2
>>> STATES.NOT_ONLINE.for_constant('DRAFT') is STATES.for_constant('DRAFT')
True
>>> STATES.NOT_ONLINE.ONLINE
Traceback (most recent call last):
...
AttributeError: 'Choices' object has no attribute 'ONLINE'

Raises:ValueError –

• If name is already an attribute of the Choices instance. * If a constant is not defined as a constant in the Choices instance.

choices

Property that returns a tuple formatted as expected by Django.

Example

>>> MY_CHOICES = Choices(('FOO', 1, 'foo'), ('BAR', 2, 'bar'))
>>> MY_CHOICES.choices
((1, 'foo'), (2, 'bar'))

extract_subset(*constants)

Create a subset of entries

This subset is a new Choices instance, with only the wanted constants from the main Choices (each “choice entry” in the subset is shared from the main Choices)

Parameters:*constants (list) – The constants names of this Choices object to make available in the subset. Returns:The newly created subset, which is a Choices object Return type:Choices

Example

>>> STATES = Choices(
...     ('ONLINE',  1, 'Online'),
...     ('DRAFT',   2, 'Draft'),
...     ('OFFLINE', 3, 'Offline'),
... )
>>> STATES
[('ONLINE', 1, 'Online'), ('DRAFT', 2, 'Draft'), ('OFFLINE', 3, 'Offline')]
>>> subset = STATES.extract_subset('DRAFT', 'OFFLINE')
>>> subset
[('DRAFT', 2, 'Draft'), ('OFFLINE', 3, 'Offline')]
>>> subset.DRAFT
2
>>> subset.for_constant('DRAFT') is STATES.for_constant('DRAFT')
True
>>> subset.ONLINE
Traceback (most recent call last):
...
AttributeError: 'Choices' object has no attribute 'ONLINE'

Raises:ValueError – If a constant is not defined as a constant in the Choices instance.

for_constant(constant)

Returns the ChoiceEntry for the given constant.

Parameters:constant (string) – Name of the constant for which we want the choice entry. Returns:The instance of ChoiceEntry for the given constant. Return type:ChoiceEntry Raises:KeyError – If the constant is not an existing one.

Example

>>> MY_CHOICES = Choices(('FOO', 1, 'foo'), ('BAR', 2, 'bar'))
>>> MY_CHOICES.for_constant('FOO')
('FOO', 1, 'foo')
>>> MY_CHOICES.for_constant('FOO').value
1
>>> MY_CHOICES.for_constant('QUX')
Traceback (most recent call last):
...
KeyError: 'QUX'

for_display(display)

Returns the ChoiceEntry for the given display name.

Parameters:display (string) – Display name for which we want the choice entry. Returns:The instance of ChoiceEntry for the given display name. Return type:ChoiceEntry Raises:KeyError – If the display name is not an existing one.

Example

>>> MY_CHOICES = Choices(('FOO', 1, 'foo'), ('BAR', 2, 'bar'))
>>> MY_CHOICES.for_display('foo')
('FOO', 1, 'foo')
>>> MY_CHOICES.for_display('foo').constant
'FOO'
>>> MY_CHOICES.for_display('qux')
Traceback (most recent call last):
...
KeyError: 'qux'

for_value(value)

Returns the ChoiceEntry for the given value.

Parameters:value – Value for which we want the choice entry. Returns:The instance of ChoiceEntry for the given value. Return type:ChoiceEntry Raises:KeyError – If the value is not an existing one.

Example

>>> MY_CHOICES = Choices(('FOO', 1, 'foo'), ('BAR', 2, 'bar'))
>>> MY_CHOICES.for_value(1)
('FOO', 1, 'foo')
>>> MY_CHOICES.for_value(1).display
'foo'
>>> MY_CHOICES.for_value(3)
Traceback (most recent call last):
...
KeyError: 3

has_constant(constant)

Check if the current Choices object has the given constant.

Parameters:constant (string) – Name of the constant we want to check.. Returns:True if the constant is present, False otherwise. Return type:boolean

Example

>>> MY_CHOICES = Choices(('FOO', 1, 'foo'), ('BAR', 2, 'bar'))
>>> MY_CHOICES.has_constant('FOO')
True
>>> MY_CHOICES.has_constant('QUX')
False

has_display(display)

Check if the current Choices object has the given display name.

Parameters:display (string) – Display name we want to check.. Returns:True if the display name is present, False otherwise. Return type:boolean

Example

>>> MY_CHOICES = Choices(('FOO', 1, 'foo'), ('BAR', 2, 'bar'))
>>> MY_CHOICES.has_display('foo')
True
>>> MY_CHOICES.has_display('qux')
False

has_value(value)

Check if the current Choices object has the given value.

Parameters:value – Value we want to check. Returns:True if the value is present, False otherwise. Return type:boolean

Example

>>> MY_CHOICES = Choices(('FOO', 1, 'foo'), ('BAR', 2, 'bar'))
>>> MY_CHOICES.has_value(1)
True
>>> MY_CHOICES.has_value(3)
False

class extended_choices.choices.OrderedChoices(*choices, **kwargs)

Bases: extended_choices.choices.Choices

Simple subclass of Choices using OrderedDict as dict_class

Example

Start by declaring your Choices:

>>> ALIGNMENTS = OrderedChoices(
...     ('BAD', 10, 'bad'),
...     ('NEUTRAL', 20, 'neutral'),
...     ('CHAOTIC_GOOD', 30, 'chaotic good'),
...     ('GOOD', 40, 'good'),
... )

>>> ALIGNMENTS.dict_class
<class 'collections.OrderedDict'>

>>> ALIGNMENTS.constants
OrderedDict([('BAD', ('BAD', 10, 'bad')), ('NEUTRAL', ('NEUTRAL', 20, 'neutral')), ('CHAOTIC_GOOD', ('CHAOTIC_GOOD', 30, 'chaotic good')), ('GOOD', ('GOOD', 40, 'good'))])
>>> ALIGNMENTS.values
OrderedDict([(10, ('BAD', 10, 'bad')), (20, ('NEUTRAL', 20, 'neutral')), (30, ('CHAOTIC_GOOD', 30, 'chaotic good')), (40, ('GOOD', 40, 'good'))])
>>> ALIGNMENTS.displays
OrderedDict([('bad', ('BAD', 10, 'bad')), ('neutral', ('NEUTRAL', 20, 'neutral')), ('chaotic good', ('CHAOTIC_GOOD', 30, 'chaotic good')), ('good', ('GOOD', 40, 'good'))])

class extended_choices.choices.AutoDisplayChoices(*choices, **kwargs)

Bases: extended_choices.choices.OrderedChoices

Subclass of OrderedChoices that will compose the display value based on the constant.

To compose the display value, it will call a display_transform function, that is defined as a class attribute but can be overridden by passing it to the constructor.

Example

>>> ALIGNMENTS = AutoDisplayChoices(
...     ('BAD', 10),
...     ('NEUTRAL', 20),
...     ('CHAOTIC_GOOD', 30, 'THE CHAOS'),
...     ('GOOD', 40, {'additional': 'attributes'}),
... )

>>> ALIGNMENTS.BAD.display
'Bad'
>>> ALIGNMENTS.NEUTRAL.choice_entry
('NEUTRAL', 20, 'Neutral')
>>> ALIGNMENTS.CHAOTIC_GOOD.display
'THE CHAOS'
>>> ALIGNMENTS.GOOD.choice_entry.additional
'attributes'

static display_transform(const)

class extended_choices.choices.AutoChoices(*choices, **kwargs)

Bases: extended_choices.choices.AutoDisplayChoices

Subclass of AutoDisplayChoices that will also compose the value to be saved based on the constant.

To compose the display value, it will call a display_transform function, that is defined as a class attribute but can be overridden by passing it to the constructor.

In this class, the *choices argument can simply be strings, or tuples with one element (or two to add additional attributes)

Example

>>> ALIGNMENTS = AutoChoices(
...     'BAD',
...     ('NEUTRAL', ),
...     ('CHAOTIC_GOOD', 'chaos', 'THE CHAOS'),
...     ('GOOD', None, 'Yeah', {'additional': 'attributes'}),
... )

>>> ALIGNMENTS.BAD.value
'bad'
>>> ALIGNMENTS.BAD.display
'Bad'
>>> ALIGNMENTS.NEUTRAL.choice_entry
('NEUTRAL', 'neutral', 'Neutral')
>>> ALIGNMENTS.CHAOTIC_GOOD.value
'chaos'
>>> ALIGNMENTS.CHAOTIC_GOOD.display
'THE CHAOS'
>>> ALIGNMENTS.GOOD.value
'good'
>>> ALIGNMENTS.GOOD.display
'Yeah'
>>> ALIGNMENTS.GOOD.choice_entry.additional
'attributes'

add_choices(*choices, **kwargs)

Disallow super method to thing the first argument is a subset name

static value_transform(const)

extended_choices.fields module

Provides a form field for django to use constants instead of values as available values.

Notes

The documentation format in this file is numpydoc.

class extended_choices.fields.NamedExtendedChoiceFormField(choices, *args, **kwargs)

Bases: django.forms.fields.Field

Field to use with choices where values are constant names instead of choice values.

Should not be very useful in normal HTML form, but if API validation is done via a form, it will to have more readable constants in the API that values

to_python(value)

Convert the constant to the real choice value.

extended_choices.helpers module

Provides classes used to construct a full Choices instance.

Notes

The documentation format in this file is numpydoc.

class extended_choices.helpers.ChoiceAttributeMixin(value, choice_entry)

Bases: future.types.newobject.newobject

Base class to represent an attribute of a ChoiceEntry.

Used for constant, name, and display.

It must be used as a mixin with another type, and the final class will be a type with added attributes to access the ChoiceEntry instance and its attributes.

choice_entry

The ChoiceEntry instance that hold the current value, used to access its constant, value and display name.

Type:instance of ChoiceEntry

constant

Returns the choice field holding the constant of the attached ChoiceEntry.

Type:property

value

Returns the choice field holding the value of the attached ChoiceEntry.

Type:property

display

Returns the choice field holding the display name of the attached ChoiceEntry.

Type:property

original_value

The value used to create the current instance.

Type:?

creator_type

The class that created a new class. Will be ChoiceAttributeMixin except if it was overridden by the author.

Type:type

Example

Classes can be created manually:

>>> class IntChoiceAttribute(ChoiceAttributeMixin, int): pass
>>> field = IntChoiceAttribute(1, ChoiceEntry(('FOO', 1, 'foo')))
>>> field
1
>>> field.constant, field.value, field.display
('FOO', 1, 'foo')
>>> field.choice_entry
('FOO', 1, 'foo')

Or via the get_class_for_value class method:

>>> klass = ChoiceAttributeMixin.get_class_for_value(1.5)
>>> klass.__name__
'FloatChoiceAttribute'
>>> float in klass.mro()
True

constant

Property that returns the constant attribute of the attached ChoiceEntry.

display

Property that returns the display attribute of the attached ChoiceEntry.

classmethod get_class_for_value(value)

Class method to construct a class based on this mixin and the type of the given value.

Parameters:value – The value from which to extract the type to create the new class.

Notes

The create classes are cached (in cls.__classes_by_type) to avoid recreating already created classes.

value

Property that returns the value attribute of the attached ChoiceEntry.

class extended_choices.helpers.ChoiceEntry

Bases: tuple

Represents a choice in a Choices object, with easy access to its attribute.

Expecting a tuple with three entries. (constant, value, display name), it will add three attributes to access then: constant, value and display.

By passing a dict after these three first entries, in the tuple, it’s also possible to add some other attributes to the ChoiceEntry` instance.

Parameters:tuple (tuple) – A tuple with three entries, the name of the constant, the value, and the display name. A dict could be added as a fourth entry to add additional attributes.

Example

>>> entry = ChoiceEntry(('FOO', 1, 'foo'))
>>> entry
('FOO', 1, 'foo')
>>> (entry.constant, entry.value, entry.display)
('FOO', 1, 'foo')
>>> entry.choice
(1, 'foo')

You can also pass attributes to add to the instance to create:

>>> entry = ChoiceEntry(('FOO', 1, 'foo', {'bar': 1, 'baz': 2}))
>>> entry
('FOO', 1, 'foo')
>>> entry.bar
1
>>> entry.baz
2

Raises:AssertionError – If the number of entries in the tuple is not expected. Must be 3 or 4.

class ChoiceAttributeMixin(value, choice_entry)

Bases: future.types.newobject.newobject

Base class to represent an attribute of a ChoiceEntry.

Used for constant, name, and display.

It must be used as a mixin with another type, and the final class will be a type with added attributes to access the ChoiceEntry instance and its attributes.

choice_entry

The ChoiceEntry instance that hold the current value, used to access its constant, value and display name.

Type:instance of ChoiceEntry

constant

Returns the choice field holding the constant of the attached ChoiceEntry.

Type:property

value

Returns the choice field holding the value of the attached ChoiceEntry.

Type:property

display

Returns the choice field holding the display name of the attached ChoiceEntry.

Type:property

original_value

The value used to create the current instance.

Type:?

creator_type

The class that created a new class. Will be ChoiceAttributeMixin except if it was overridden by the author.

Type:type

Example

Classes can be created manually:

>>> class IntChoiceAttribute(ChoiceAttributeMixin, int): pass
>>> field = IntChoiceAttribute(1, ChoiceEntry(('FOO', 1, 'foo')))
>>> field
1
>>> field.constant, field.value, field.display
('FOO', 1, 'foo')
>>> field.choice_entry
('FOO', 1, 'foo')

Or via the get_class_for_value class method:

>>> klass = ChoiceAttributeMixin.get_class_for_value(1.5)
>>> klass.__name__
'FloatChoiceAttribute'
>>> float in klass.mro()
True

constant

Property that returns the constant attribute of the attached ChoiceEntry.

display

Property that returns the display attribute of the attached ChoiceEntry.

classmethod get_class_for_value(value)

Class method to construct a class based on this mixin and the type of the given value.

Parameters:value – The value from which to extract the type to create the new class.

Notes

The create classes are cached (in cls.__classes_by_type) to avoid recreating already created classes.

value

Property that returns the value attribute of the attached ChoiceEntry.

extended_choices.helpers.create_choice_attribute(creator_type, value, choice_entry)

Create an instance of a subclass of ChoiceAttributeMixin for the given value.

Parameters:

• creator_type (type) – ChoiceAttributeMixin or a subclass, from which we’ll call the get_class_for_value class-method.
• value – The value for which we want to create an instance of a new subclass of creator_type.
• choice_entry (ChoiceEntry) – The ChoiceEntry instance that hold the current value, used to access its constant, value and display name.

Returns:

An instance of a subclass of creator_type for the given value

Return type:

ChoiceAttributeMixin

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