django-clever-selects 1.0.0

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)
    color = ChainedChoiceField(parent_field='model', ajax_url=reverse_lazy('ajax_chained_colors'),
        empty_label=_(u'Select a car model'), 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.

In order to pre-populate child fields, the form can need to have access to the current user. This can be done by passing the user to the kwargs of the form’s __init__() method in the form’s view. The ChainedSelectFormViewMixin takes care of this for you.:

class CreateCarView(ChainedSelectFormViewMixin, CreateView)
    template_name = "create_car.html"
    form_class = ModelChainForm
    model = Car

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 like this:

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))

or like this:

class AjaxChainedView(ChainedSelectChoicesView):
    def get_child_set(self):
        return ChildModel.object.filter(parent_id=self.parent_value)

Don’t forget to update your urls.py:

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