fix openapi fields rendering for range type filters

django_filters/rest_framework/backends.py

@@ -113,6 +113,29 @@ def get_coreschema_field(self, field):
             description=str(field.extra.get('help_text', ''))
         )
 
+    def build_coreapi_field(self, name, field):
+        return compat.coreapi.Field(
+            name=name,
+            required=field.extra['required'],
+            location='query',
+            schema=self.get_coreschema_field(field),
+        )
+
+    def get_schema_field_names(self, field_name, field):
+        """
+        Get the corresponding schema field names required to generate the openAPI schema
+        by referencing the widget suffixes if available.
+        """
+        try:
+            suffixes = field.field_class.widget.suffixes
+        except AttributeError:
+            return [field_name]
+        else:
+            return [field_name] if not suffixes else [
+                '{}_{}'.format(field_name, suffix)
+                for suffix in suffixes if suffix
+            ]
+
     def get_schema_fields(self, view):
         # This is not compatible with widgets where the query param differs from the
         # filter's attribute name. Notably, this includes `MultiWidget`, where query
@@ -130,14 +153,13 @@ def get_schema_fields(self, view):
 
         filterset_class = self.get_filterset_class(view, queryset)
 
-        return [] if not filterset_class else [
-            compat.coreapi.Field(
-                name=field_name,
-                required=field.extra['required'],
-                location='query',
-                schema=self.get_coreschema_field(field)
-            ) for field_name, field in filterset_class.base_filters.items()
-        ]
+        if not filterset_class:
+            return []
+
+        return [self.build_coreapi_field(schema_field_name, field)
+                for field_name, field in filterset_class.base_filters.items()
+                for schema_field_name in self.get_schema_field_names(field_name, field)
+                ]
 
     def get_schema_operation_parameters(self, view):
         try:

tests/rest_framework/test_backends.py

@@ -241,6 +241,46 @@ class View(FilterClassRootView):
 
         self.assertEqual(fields, ['text', 'decimal', 'date', 'f'])
 
+    def test_fields_with_range_type_filter_default_suffixes(self):
+
+        class F(SeveralFieldsFilter):
+            date = filters.DateFromToRangeFilter()
+
+        class View(FilterClassRootView):
+            filterset_class = F
+
+        view = View()
+        backend = DjangoFilterBackend()
+        fields = backend.get_schema_fields(view)
+        field_names = [f.name for f in fields]
+
+        self.assertIn("date_after", field_names)
+        self.assertIn("date_before", field_names)
+
+    def test_fields_with_range_type_filter_with_custom_suffixes(self):
+        custom_suffixes = ['previous', 'later']
+
+        mock_widget = mock.Mock(suffixes=custom_suffixes)
+        mock_field_class = mock.Mock(widget=mock_widget)
+
+        class CustomDateFromtoRangeFilter(filters.DateFromToRangeFilter):
+            field_class = mock_field_class
+
+        class F(SeveralFieldsFilter):
+            date = CustomDateFromtoRangeFilter()
+
+        class View(FilterClassRootView):
+            filterset_class = F
+
+        view = View()
+
+        backend = DjangoFilterBackend()
+        fields = backend.get_schema_fields(view)
+        field_names = [f.name for f in fields]
+
+        for custom_suffix in custom_suffixes:
+            self.assertIn('date_{}'.format(custom_suffix), field_names)
+
 
 class GetSchemaOperationParametersTests(TestCase):
     def test_get_operation_parameters_with_filterset_fields_list(self):