RadioSelect, RadioSelectMultiple, CheckBoxSelect, CheckBoxSelectMultiple do not render nested option sets correctly

[Dylan Verheul]

The Select widget is the default widget to handle fields that make use of choices. These are commonly rendered as a HTML select, as implemented for django.forms.widgets.Select.

Sometimes a series of radio buttons or checkboxes is a better fir for the UI. Django supports this by implementing widgets that can stand in for Select. These are RadioSelect, RadioSelectMultiple, CheckBoxSelect, CheckBoxSelectMultiple.

The choices to render are implemented as a n iterable of 2-tuples as documented here:
​https://docs.djangoproject.com/en/dev/ref/models/fields/#field-choices

As stated in the documentation, choices can be grouped for organizational purposes. The example given:

MEDIA_CHOICES = (
    ('Audio', (
            ('vinyl', 'Vinyl'),
            ('cd', 'CD'),
        )
    ),
    ('Video', (
            ('vhs', 'VHS Tape'),
            ('dvd', 'DVD'),
        )
    ),
    ('unknown', 'Unknown'),
)

When using a Select or SelectMultiple widget, these groups are rendered as HTML optgroup elements. This is correct.

When using any of the other widgets mentioned, the organizational groups are not taken into account when rendering the widget. Instead, the entire group is forced to text without escaping, resulting in a single widget for each group, with the text representation of the list as its label (newlines and spaces added for better readability):

<label for="id_category3_0">
    <input id="id_category3_0" name="category3" placeholder="Category3" title="" type="radio" value="Audio" />
    ((&#39;vinyl&#39;, &#39;Vinyl&#39;), (&#39;cd&#39;, &#39;CD&#39;))
</label>

The solution for this would be take have the renders of these widgets mimic the behavior of Select.render_options, but instead of optgroup an extra level of ul would have to be generated. In pseudo-HTML, for the given example:

<ul>
    <li>
        Audio
            <ul>
                <li>(input element for vinyl</li>
                <li>(input element for CD</li>
            </ul>
    </li>
    ....
</ul>

[Christopher Babiak]

Cannot find a "RadioSelectMultiple" or "CheckBoxSelect" widget anywhere in Django. Keeping RadioSelect & CheckboxSelectMultiple, but ignoring those two.

[Christopher Babiak]

Submitted pull request. ​https://github.com/django/django/pull/1683

[Julien Phalip <jphalip@…>]

In a834bc84d8c76d4a7016ac4db4f631a8bcaa3d0b:

Fixed #20931 -- Fixed select widgets nested choice rendering

ChoiceFieldRenderer was not rendering nested choices. Added recursion
to ChoiceFieldRenderer to take nested choices and render them as
<ul>'s.