I'm following along in the [DAL documentation](http://django-autocomplete-light.readthedocs.io/en/master/tutorial.html#filtering-results-based-on-the-value-of-other-fields-in-the-form) to add a filtered field to my form, but the forwarding isn't working to connect one field to the other:

**Forms.py**

```
class PurchaseForm(forms.ModelForm):

    commodity = forms.ModelChoiceField(
        queryset=Commodity.objects.all(),
        widget=autocomplete.ModelSelect2(url='commodity-autocomplete'),
        required=False,
    )

    class Meta:
        model = Purchase
        fields = ["variety"]
        widgets = {
            'variety': autocomplete.ModelSelect2(url='variety-autocomplete', forward=['commodity'],   
        }

```

**Views.py**

```
class VarietyAutocompleteView(autocomplete.Select2QuerySetView):
    def get_queryset(self):
        qs = Variety.objects.all()

        commodity = self.forwarded.get('commodity', None)
        print("Commodity:" + str(commodity))
        if commodity:
            qs = qs.filter(commodity=commodity)

        if self.q:
            qs = qs.filter(name__istartswith=self.q)

        return qs

```

I'd like my Variety choices to be filtered by their foreign key relationship to Commodity objects. Both autocomplete fields are working on their own just fine, but the choice from the `commodity` field is not being forwarded to the `VarietyAutocompleteView` (my print command prints `Commodity:None`). Is this perhaps because I am passing a foreign key object? Or have I set this up incorrectly somehow?