django-rest-framework Fix #7722.

Render BooleanFields with allow_null=True as HTML select rather than as HTML checkbox in Browsable API #7722.

Description

This PR is created in order to fix issue #7722. A serializer field of type BooleanField with allow_null=True was being rendered as HTML checkbox elements on Browsable API forms even though three values (True, False, and None/null) are possible. It was also happening for the model BooleanField instances with allow_null=True that are converted to serializer BooleanField instances. In this PR, I worked on keeping the checkbox rendering for BooleanFields with allow_null=False while providing dropdown rendering (HTML select element) for BooleanFields with allow_null=True.

fix #7722 refs #7722

Mar 29 '21 14:03 tbrknt

Thanks for working on this. Having a look over, I'm wondering about the alternative of not introducing a new template, and using the existing "select.html" template.

Mar 29 '21 14:03 tomchristie

Hi @tomchristie , Thank you for your comment. I was thinking about that alternative too. The following part from select.html was my main hesitation to use it. I was not sure if I should adapt the value of BooleanField and that part of the template. Without changing that template, I could not think of a solution to drop -------- and introduce unknown option. What do you think about it? If unknown option is not that important, I believe it is possible to make the value of the BoundField as 'False' string instead of False boolean value. That way, for False, we can avoid if not field.value.

  <select class="form-control" name="{{ field.name }}">
    {% if field.allow_null or field.allow_blank %}
      <option value="" {% if not field.value %}selected{% endif %}>--------</option>
    {% endif %}
  </select>

Mar 29 '21 15:03 tbrknt