Question

class CreateCourseForm(ModelForm):
        category = forms.ModelChoiceField(
            queryset=Category.objects.all(),
            empty_label="",
            #widget=CustomCourseWidget()
        )

    class Meta:
        model = Course
        fields = ('title', 'description', 'category')

    def __init__(self, *args, **kwargs):
        super(CreateCourseForm, self).__init__(*args, **kwargs)
        self.fields['category'].widget.attrs['class'] = 'chzn-select'
        self.fields['category'].widget.attrs['data-placeholder'] = u'Please select one'

With the code above, I’m getting a select-box with all the Category-Objects listed. What I’m trying to do is to add a

<optgroup>VALUE</optgroup> 

HTML-element to specific Category-Objects (the ones with Category.parent == null).

Does anyone know how to do that? Thanks a lot!

PS: I already tried converting the QuerySet to a Choices-Set (e.g. http://dealingit.wordpress.com/2009/10/26/django-tip-showing-optgroup-in-a-modelform/), which works fine for rendering the HTML – until I try to save the results into the DB, where a mismatching occurs (ValueError).

Answer 1

Here is my current solution. It might be a dirty fix, but it works fine 🙂

class CustomCourseWidget(forms.Select):
    #http://djangosnippets.org/snippets/200/
    def render(self, name, value, attrs=None, choices=()):
        from django.utils.html import escape
        from django.utils.encoding import smart_unicode
        from django.forms.util import flatatt

        if value is None:
            value = ''
        final_attrs = self.build_attrs(attrs, name=name)
        output = [u'<select%s>' % flatatt(final_attrs)]
        output.append(u'<option value=""></option>') # Empty line for default text
        str_value = smart_unicode(value)
        optgroup_open = False
        for group in self.choices:
            option_value = smart_unicode(group[0])
            option_label = smart_unicode(group[1])
            if not ">" in option_label and optgroup_open == True:
                output.append(u'</optgroup>')
                optgroup_open = False
            if not ">" in option_label and optgroup_open == False:
                output.append(u'<optgroup label="%s">' % escape(option_label))
                optgroup_open = True
            if " > " in option_label:
                #optgroup_open = True
                selected_html = (option_value == str_value) and u' selected="selected"' or ''
                output.append(u'<option value="%s"%s>%s</option>' % (escape(option_value), selected_html, escape(option_label.split(" > ")[1])))

        output.append(u'</select>')
        return mark_safe(u'\n'.join(output))