Commit 74e1980c authored by Peter Inglesby's avatar Peter Inglesby Committed by Tim Graham
Browse files

Fixed #13181 -- Added support for callable choices to forms.ChoiceField 

Thanks vanschelven and expleo for the initial patch.
parent e0685368

django/forms/fields.py

+15 −1
Original line number Diff line number Diff line
@@ -798,6 +798,15 @@ class NullBooleanField(BooleanField): 
        return initial != data





class CallableChoiceIterator(object):

    def __init__(self, choices_func):

        self.choices_func = choices_func



    def __iter__(self):

        for e in self.choices_func():

            yield e





class ChoiceField(Field):

    widget = Select

    default_error_messages = {
@@ -822,7 +831,12 @@ class ChoiceField(Field): 
        # Setting choices also sets the choices on the widget.

        # choices can be any iterable, but we call list() on it because

        # it will be consumed more than once.

        self._choices = self.widget.choices = list(value)

        if callable(value):

            value = CallableChoiceIterator(value)

        else:

            value = list(value)



        self._choices = self.widget.choices = value



    choices = property(_get_choices, _set_choices)

docs/ref/forms/fields.txt

+10 −4
Original line number Diff line number Diff line
@@ -387,10 +387,16 @@ For each field, we describe the default widget used if you don't specify 


    .. attribute:: choices



        An iterable (e.g., a list or tuple) of 2-tuples to use as choices for this

        field. This argument accepts the same formats as the ``choices`` argument

        to a model field. See the :ref:`model field reference documentation on

        choices <field-choices>` for more details.

        Either an iterable (e.g., a list or tuple) of 2-tuples to use as

        choices for this field, or a callable that returns such an iterable.

        This argument accepts the same formats as the ``choices`` argument to a

        model field. See the :ref:`model field reference documentation on

        choices <field-choices>` for more details. If the argument is a

        callable, it is evaluated each time the field's form is initialized.



        .. versionchanged:: 1.8



            The ability to pass a callable to ``choices`` was added.



``TypedChoiceField``

~~~~~~~~~~~~~~~~~~~~

docs/releases/1.8.txt

+3 −0
Original line number Diff line number Diff line
@@ -240,6 +240,9 @@ Forms 
  will also update ``UploadedFile.content_type`` with the image's content type

  as determined by Pillow.



* You can now pass a callable that returns an iterable of choices when

  instantiating a :class:`~django.forms.ChoiceField`.



Generic Views

^^^^^^^^^^^^^

tests/forms_tests/tests/test_fields.py

+22 −0
Original line number Diff line number Diff line
@@ -961,6 +961,28 @@ class FieldsTests(SimpleTestCase): 
        self.assertEqual('5', f.clean('5'))

        self.assertRaisesMessage(ValidationError, "'Select a valid choice. 6 is not one of the available choices.'", f.clean, '6')



    def test_choicefield_callable(self):

        choices = lambda: [('J', 'John'), ('P', 'Paul')]

        f = ChoiceField(choices=choices)

        self.assertEqual('J', f.clean('J'))



    def test_choicefield_callable_may_evaluate_to_different_values(self):

        choices = []



        def choices_as_callable():

            return choices



        class ChoiceFieldForm(Form):

            choicefield = ChoiceField(choices=choices_as_callable)



        choices = [('J', 'John')]

        form = ChoiceFieldForm()

        self.assertEqual([('J', 'John')], list(form.fields['choicefield'].choices))



        choices = [('P', 'Paul')]

        form = ChoiceFieldForm()

        self.assertEqual([('P', 'Paul')], list(form.fields['choicefield'].choices))



    # TypedChoiceField ############################################################

    # TypedChoiceField is just like ChoiceField, except that coerced types will

    # be returned: