django-clever-selects 0.6.1

Forms

Form must inherit from ChainedChoicesMixin (or from ChainedChoicesForm / ChainedChoicesModelForm, depends on your needs) which loads the options when there is already an instance or initial data:

from clever_selects.form_fields import ChainedChoiceField
from clever_selects.forms import ChainedChoicesForm


class SimpleChainForm(ChainedChoicesForm):
    first_field = ChoiceField(choices=(('', '------------'), (1, '1'), (2, '2'), (3, '3'), (4, '4'), (5, '5'), ))
    second_field = ChainedChoiceField(parent_field='first_field', ajax_url=reverse_lazy('ajax_chained_view'))


class MultipleChainForm(ChainedChoicesForm):
    first_field = ChoiceField(choices=(('', '------------'), (6, 6), (7, 7), (8, 8), (9, 9), (10, 10), ))
    second_field = ChainedChoiceField(parent_field='first_field', ajax_url=reverse_lazy('ajax_chained_view'))
    third_field = ChainedChoiceField(parent_field='second_field', ajax_url=reverse_lazy('ajax_chained_view'))
    fourth_field = ChainedChoiceField(parent_field='third_field', ajax_url=reverse_lazy('ajax_chained_view'))
    fifth_field = ChainedChoiceField(parent_field='fourth_field', ajax_url=reverse_lazy('ajax_chained_view'))


class ModelChainForm(ChainedChoicesModelForm):
    brand = forms.ModelChoiceField(queryset=CarBrand.objects.all(), required=True,
        empty_label=_(u'Select a car brand'))
    model = ChainedModelChoiceField(parent_field='brand', ajax_url=reverse_lazy('ajax_chained_models'),
        empty_label=_(u'Select a car model'), model=BrandModel, required=True)
    engine = forms.ChoiceField(choices=([('', _('All engine types'))] + Car.ENGINES), required=False)

    class Meta:
        model = Car

Notice that ajax URLs could differ of each field for different purposes. See example project for more use cases.

Views

Ajax call is made whenever the parent field is changed. You must set up the ajax URL to return json list of lists:

class AjaxChainedView(BaseDetailView):
    """
    View to handle the ajax request for the field options.
    """

    def get(self, request, *args, **kwargs):
        field = request.GET.get('field')
        parent_value = request.GET.get("parent_value")

        vals_list = []
        for x in range(1, 6):
            vals_list.append(x*int(parent_value))

        choices = tuple(zip(vals_list, vals_list))

        response = HttpResponse(
            json.dumps(choices, cls=DjangoJSONEncoder),
            mimetype='application/javascript'
        )
        add_never_cache_headers(response)
        return response

Or you can use ChainedSelectChoicesView class helper:

class AjaxChainedView(ChainedSelectChoicesView):
    def get_choices(self):
        vals_list = []
        for x in range(1, 6):
            vals_list.append(x*int(self.parent_value))
        return tuple(zip(vals_list, vals_list))

Don’t forget to update your urls.py:

url(r'^ajax/custom-chained-view-url/$', AjaxChainedView.as_view(), name='ajax_chained_view'),