Change Django autocomplete_fields label

Question

I'm trying to set a custom label for all of the items of a type in autocomplete_fields.

Until now, for a drop-down list, one would use

...
class CustomDisplay(forms.ModelChoiceField):
    def label_from_instance(self, obj):
        return "Some custom text: {}".format(obj.name)
...
somethings = CustomDisplay(queryset=Something.object.all())
...

but using this with autocomplete_fields = (somethings,) will result in autocomplete canceling and showing me a dropdown with the custom text.

Answer 1

The reason the field shows a normal select widget is that, when you define your custom field, you don't set the widget as an AutocompleteSelect.

In the ModelAdmin class where you specify your autocomplete_fields, import your CustomDisplay and AutocompleteSelect and add the following method:

from django.contrib.admin.widgets import AutocompleteSelect


class YourModelAdmin(admin.ModelAdmin):
    autocomplete_fields = ['something']

    ...

    def formfield_for_foreignkey(self, db_field, request, **kwargs):
        db = kwargs.get('using')

        if db_field.name == 'something':
            return CustomDisplay(queryset=Something.object.all(), widget=AutocompleteSelect(db_field.remote_field, self.admin_site, using=db))
        return super().formfield_for_foreignkey(db_field, request, **kwargs)

That will only display the custom text when you view an existing instance. When you view the autocomplete drop down, and select an entry, the label is not generated from label_from_instance(), but from a straightforward str() call inside AutocompleteJsonView.

So assuming you only want to change the label in the autocomplete widget (to change the label across the board you would obviously just change the model __str()__ method), you also need to create a custom class in admin.py that modifies the get() method in AutocompleteJsonView:

from django.contrib.admin.options import AutocompleteJsonView
from django.http import Http404, JsonResponse

class CustomAutocompleteJsonView(AutocompleteJsonView):
    def get(self, request, *args, **kwargs):
        if not self.model_admin.get_search_fields(request):
            raise Http404(
                '%s must have search_fields for the autocomplete_view.' %
                type(self.model_admin).__name__
            )
        if not self.has_perm(request):
            return JsonResponse({'error': '403 Forbidden'}, status=403)

        self.term = request.GET.get('term', '')
        self.paginator_class = self.model_admin.paginator
        self.object_list = self.get_queryset()
        context = self.get_context_data()

        # Replace this with the code below.
        #
        # return JsonResponse({
        #     'results': [
        #         {'id': str(obj.pk), 'text': str(obj)}
        #         for obj in context['object_list']
        #     ],
        #     'pagination': {'more': context['page_obj'].has_next()},
        # })

        return JsonResponse({
            'results': [
                {'id': str(obj.pk), 'text': 'Some custom text: {}'.format(obj.name)}
                for obj in context['object_list']
            ],
            'pagination': {'more': context['page_obj'].has_next()},
    })

Now set the autocomplete_view on the ModelAdmin class that the autocomplete is displaying results for (not the ModelAdmin class where you specify autocomplete_fields):

def autocomplete_view(self, request):
    return CustomAutocompleteJsonView.as_view(model_admin=self)(request)

So if you have a ModelAdmin class called YourModelAdmin with autocomplete_fields = ['something'], you would set the autocomplete_view for the corresponding ModelAdmin class for your Something model.