Improve CountryFilter to play nice with multiple=True

django_countries/filters.py

@@ -13,13 +13,20 @@ class CountryFilter(admin.FieldListFilter):
     title = _("Country")  # type: ignore
 
     def expected_parameters(self):
+        if self.field.multiple:
+            return [f"{self.field.name}__contains"]
         return [self.field.name]
 
     def choices(self, changelist):
-        value = self.used_parameters.get(self.field.name)
+        if self.field.multiple:
+            field_name = f"{self.field.name}__contains"
+        else:
+            field_name = self.field.name
+
+        value = self.used_parameters.get(field_name)
         yield {
             "selected": value is None,
-            "query_string": changelist.get_query_string({}, [self.field.name]),
+            "query_string": changelist.get_query_string({}, [field_name]),
             "display": _("All"),
         }
         for lookup, title in self.lookup_choices(changelist):
@@ -29,18 +36,18 @@ def choices(self, changelist):
                 selected = force_str(lookup) == value
             yield {
                 "selected": selected,
-                "query_string": changelist.get_query_string(
-                    {self.field.name: lookup}, []
-                ),
+                "query_string": changelist.get_query_string({field_name: lookup}, []),
                 "display": title,
             }
 
     def lookup_choices(self, changelist):
         qs = changelist.model._default_manager.all()
         codes = set(
-            qs.distinct()
-            .order_by(self.field.name)
-            .values_list(self.field.name, flat=True)
+            ",".join(
+                qs.distinct()
+                .order_by(self.field.name)
+                .values_list(self.field.name, flat=True)
+            ).split(",")
         )
         for k, v in self.field.get_choices(include_blank=False):
             if k in codes:

django_countries/tests/test_admin_filters.py

@@ -19,6 +19,13 @@ class PersonAdmin(admin.ModelAdmin):
 test_site.register(models.Person, PersonAdmin)
 
 
+class MultiCountryAdmin(admin.ModelAdmin):
+    list_filter = [("countries", filters.CountryFilter)]
+
+
+test_site.register(models.MultiCountry, MultiCountryAdmin)
+
+
 class TestCountryFilter(TestCase):
     def get_changelist_kwargs(self):
         m = self.person_admin
@@ -74,3 +81,65 @@ def test_choices(self):
 
     def test_choices_empty_selection(self):
         return self._test_choices(selected_country_code=None)
+
+
+class TestMultiCountryFilter(TestCase):
+    def get_changelist_kwargs(self):
+        m = self.multi_country_admin
+        sig = inspect.signature(ChangeList.__init__)
+        kwargs = {"model_admin": m}
+        for arg in list(sig.parameters)[2:]:
+            if hasattr(m, arg):
+                kwargs[arg] = getattr(m, arg)
+        return kwargs
+
+    def setUp(self):
+        models.MultiCountry.objects.create(countries=["NZ"])
+        models.MultiCountry.objects.create(countries=["FR", "AU"])
+        models.MultiCountry.objects.create(countries=["FR", "NZ"])
+        self.multi_country_admin = MultiCountryAdmin(models.MultiCountry, test_site)
+
+    def test_filter_none(self):
+        request = RequestFactory().get("/multi_country/")
+        request.user = AnonymousUser()
+        cl = ChangeList(request, **self.get_changelist_kwargs())
+        cl.get_results(request)
+        self.assertEqual(len(cl.result_list), models.MultiCountry.objects.count())
+
+    def test_filter_country(self):
+        request = RequestFactory().get(
+            "/multi_country/", data={"countries__contains": "NZ"}
+        )
+        request.user = AnonymousUser()
+        cl = ChangeList(request, **self.get_changelist_kwargs())
+        cl.get_results(request)
+        self.assertQuerysetEqual(
+            cl.result_list,
+            models.MultiCountry.objects.exclude(countries__contains="AU"),
+            ordered=False,
+        )
+
+    def _test_choices(self, selected_country_code="NZ"):
+        request_params = {}
+        selected_country = "All"
+
+        if selected_country_code:
+            request_params["countries__contains"] = selected_country_code
+            selected_country = countries.name(selected_country_code)
+
+        request = RequestFactory().get("/multi_country/", data=request_params)
+        request.user = AnonymousUser()
+        cl = ChangeList(request, **self.get_changelist_kwargs())
+        choices = list(cl.filter_specs[0].choices(cl))
+        self.assertEqual(
+            [c["display"] for c in choices],
+            ["All", "Australia", "France", "New Zealand"],
+        )
+        for choice in choices:
+            self.assertEqual(choice["selected"], choice["display"] == selected_country)
+
+    def test_choices(self):
+        return self._test_choices()
+
+    def test_choices_empty_selection(self):
+        return self._test_choices(selected_country_code=None)