Features: 1) Add template attribute to BaseAutocompleteFilter for custom rendering; 2) Introduce autocomplete_filter.html template for enhanced filter display;

Fixes: 1) Correct parameter name value extraction to use `current` in `BaseAutocompleteFilter`;

Extra: 1) Refactor HTML rendering in `BaseAutocompleteFilter` for readability; 2) Add comments to explain purposes in the new template.

core/filters.py

@@ -509,6 +509,8 @@ class AddressFilter(FilterSet):
 
 
 class BaseAutocompleteFilter(SimpleListFilter):
+    template = "admin/autocomplete_filter.html"
+
     def lookups(self, request, model_admin):
         return ()
 
@@ -516,14 +518,18 @@ class BaseAutocompleteFilter(SimpleListFilter):
         url = reverse(
             f"admin:{changelist.opts.app_label}_{self.parameter_name}_autocomplete"
         )
-        qs   = changelist.get_query_string(remove=[self.parameter_name])
-        val  = changelist.params.get(self.parameter_name, "")
+        current = changelist.params.get(self.parameter_name, "")
         html = (
-            f'<input type="hidden" class="django-autocomplete admin-autocomplete-filter" '
-            f'data-autocomplete-url="{url}" name="{self.parameter_name}" value="{val}"/>'
+            f'<input type="hidden" '
+            f'class="django-autocomplete admin-autocomplete-filter" '
+            f'data-autocomplete-url="{url}" '
+            f'name="{self.parameter_name}" '
+            f'value="{current}"/>'
         )
         # noinspection DjangoSafeString
-        yield {"query_string": qs, "display": mark_safe(html)}
+        yield {
+            "display": mark_safe(html),
+        }
 
 
 class BrandAdminFilter(BaseAutocompleteFilter):

core/templates/autocomplete_filter.html

@@ -0,0 +1,11 @@
+{% comment %}
+A custom filter template that
+only cares about our `display` key.
+{% endcomment %}
+
+<div class="module filter-{{ spec.parameter_name|slugify }}">
+  <h3>{{ spec.title }}</h3>
+  {% for choice in spec.choices cl %}
+    {{ choice.display|safe }}
+  {% endfor %}
+</div>