bugfix duplicate enum list for django-filter #991

drf_spectacular/contrib/django_filters.py

@@ -259,6 +259,8 @@ def _get_field_description(self, filter_field, description):
             # remove auto-generated enum list, since choices come from a callable
             if '\n\n*' in (description or ''):
                 description, _, _ = description.partition('\n\n*')
+            elif (description or '').startswith('* `'):
+                description = ''
             return description
 
         choice_description = ''
@@ -268,14 +270,18 @@ def _get_field_description(self, filter_field, description):
         if not choices:
             return description
 
-        if description:
-            # replace or append model choice description
-            if '\n\n*' in description:
-                description, _, _ = description.partition('\n\n*')
+        if not description:
+            return choice_description
+
+        if '\n\n*' in description:
+            description, _, _ = description.partition('\n\n*')
             return description + '\n\n' + choice_description
-        else:
+
+        if description.startswith('* `'):
             return choice_description
 
+        return description + '\n\n' + choice_description
+
     @classmethod
     def _is_gis(cls, field):
         if not getattr(cls, '_has_gis', True):

tests/contrib/test_django_filters.py

@@ -377,3 +377,36 @@ def list(self, request, *args, **kwargs):
     assert schema['paths']['/x/']['get']['parameters'] == expected
     schema = generate_schema('/x', XViewset)
     assert schema['paths']['/x/']['get']['parameters'] == expected
+
+
+def test_filterset_enum_description_duplication():
+    class ThingType(models.TextChoices):
+        ONE = "one", "One"
+        TWO = "two", "Two"
+        THREE = "three", "Three"
+
+    class Thing(models.Model):
+        type = models.CharField(max_length=64, choices=ThingType.choices)
+
+    class ThingSerializer(serializers.ModelSerializer):
+        class Meta:
+            model = Thing
+            fields = ("type",)
+
+    class ThingFilterSet(FilterSet):
+        class Meta:
+            model = Thing
+            fields = ("type",)
+
+        type = ChoiceFilter(choices=ThingType.choices)
+
+    class XViewSet(viewsets.ModelViewSet):
+        queryset = Thing.objects.all()
+        serializer_class = ThingSerializer
+        filter_backends = [DjangoFilterBackend]
+        filterset_class = ThingFilterSet
+
+    schema = generate_schema('/x', XViewSet)
+    assert schema['paths']['/x/']['get']['parameters'][0]['description'] == (
+        '* `one` - One\n* `two` - Two\n* `three` - Three'
+    )