Commit 7211741f authored by Carl Meyer's avatar Carl Meyer
Browse files

Fixed #20999 - Allow overriding formfield class with choices, without subclass restrictions. 

Refs #18162. Thanks claudep and mjtamlyn for review.
parent b04f8ddb

django/db/models/fields/__init__.py

+4 −2
Original line number Diff line number Diff line
@@ -636,7 +636,7 @@ class Field(object): 
    def save_form_data(self, instance, data):

        setattr(instance, self.name, data)



    def formfield(self, form_class=None, **kwargs):

    def formfield(self, form_class=None, choices_form_class=None, **kwargs):

        """

        Returns a django.forms.Field instance for this database Field.

        """
@@ -657,7 +657,9 @@ class Field(object): 
            defaults['coerce'] = self.to_python

            if self.null:

                defaults['empty_value'] = None

            if form_class is None or not issubclass(form_class, forms.TypedChoiceField):

            if choices_form_class is not None:

                form_class = choices_form_class

            else:

                form_class = forms.TypedChoiceField

            # Many of the subclass-specific formfield arguments (min_value,

            # max_value) don't apply for choice fields, so be sure to only pass

docs/howto/custom-model-fields.txt

+13 −7
Original line number Diff line number Diff line
@@ -617,17 +617,23 @@ prepared with :meth:`.get_prep_lookup`. 
Specifying the form field for a model field

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



.. method:: Field.formfield(self, form_class=forms.CharField, **kwargs)

.. method:: Field.formfield(self, form_class=None, choices_form_class=None, **kwargs)



Returns the default form field to use when this field is displayed in a model.

This method is called by the :class:`~django.forms.ModelForm` helper.

Returns the default form field to use when this model field is displayed in a

form.  This method is called by the :class:`~django.forms.ModelForm` helper.



The form field class can be specified via the ``form_class`` and

``choices_form_class`` arguments; the latter is used if the field has choices

specified, the former otherwise. If these arguments are not provided,

:class:`~django.forms.CharField` or :class:`~django.forms.TypedChoiceField`

will be used.



All of the ``kwargs`` dictionary is passed directly to the form field's

``__init__()`` method. Normally, all you need to do is set up a good default

for the ``form_class`` argument and then delegate further handling to the

parent class. This might require you to write a custom form field (and even a

form widget). See the :doc:`forms documentation </topics/forms/index>` for

information about this.

for the ``form_class`` (and maybe ``choices_form_class``) argument and then

delegate further handling to the parent class. This might require you to write

a custom form field (and even a form widget). See the :doc:`forms documentation

</topics/forms/index>` for information about this.



Continuing our ongoing example, we can write the :meth:`.formfield` method as::

tests/model_fields/tests.py

+5 −7
Original line number Diff line number Diff line
@@ -78,14 +78,12 @@ class BasicFieldTests(test.TestCase): 


        self.assertEqual(m._meta.get_field('id').verbose_name, 'verbose pk')



    def test_formclass_with_choices(self):

        # regression for 18162

        class CustomChoiceField(forms.TypedChoiceField):

            pass

        choices = [('a@b.cc', 'a@b.cc'), ('b@b.cc', 'b@b.cc')]

    def test_choices_form_class(self):

        """Can supply a custom choices form class. Regression for #20999."""

        choices = [('a', 'a')]

        field = models.CharField(choices=choices)

        klass = CustomChoiceField

        self.assertIsInstance(field.formfield(form_class=klass), klass)

        klass = forms.TypedMultipleChoiceField

        self.assertIsInstance(field.formfield(choices_form_class=klass), klass)





class DecimalFieldTests(test.TestCase):