From df2211913f593ebf32240947024212137c0ce559 Mon Sep 17 00:00:00 2001
From: "T. Franzel" <13507857+tfranzel@users.noreply.github.com>
Date: Fri, 8 May 2020 17:56:07 +0200
Subject: [PATCH] explicit override for non-list serializers on ViewSet list
 #49

---
 drf_spectacular/openapi.py |  2 +-
 drf_spectacular/utils.py   | 18 +++++++++++++++++
 tests/test_regressions.py  | 40 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 59 insertions(+), 1 deletion(-)

diff --git a/drf_spectacular/openapi.py b/drf_spectacular/openapi.py
index 73e42458..034aae96 100644
--- a/drf_spectacular/openapi.py
+++ b/drf_spectacular/openapi.py
@@ -806,7 +806,7 @@ def _get_response_for_code(self, serializer):
             schema = build_basic_type(OpenApiTypes.OBJECT)
             schema['description'] = 'Unspecified response body'
 
-        if self._is_list_view(serializer):
+        if self._is_list_view(serializer) and not get_override(serializer, 'many') is False:
             schema = build_array_type(schema)
             paginator = self._get_paginator()
             if paginator:
diff --git a/drf_spectacular/utils.py b/drf_spectacular/utils.py
index 29ecdeef..11458cab 100644
--- a/drf_spectacular/utils.py
+++ b/drf_spectacular/utils.py
@@ -200,3 +200,21 @@ def decorator(f):
         return f
 
     return decorator
+
+
+def extend_schema_serializer(many=None):
+    """
+    Decorator for the "serializer" kind. Intended for overriding default serializer behaviour that
+    cannot be influenced through `.extend_schema`.
+
+    :param many: override how serializer is initialized. Mainly used to coerce the list view detection
+        heuristic to acknowledge a non-list serializer.
+    """
+    def decorator(klass):
+        if not hasattr(klass, '_spectacular_annotation'):
+            klass._spectacular_annotation = {}
+        if many is not None:
+            klass._spectacular_annotation['many'] = many
+        return klass
+
+    return decorator
diff --git a/tests/test_regressions.py b/tests/test_regressions.py
index 11f4e5fa..56e6a357 100644
--- a/tests/test_regressions.py
+++ b/tests/test_regressions.py
@@ -493,3 +493,43 @@ def get(self, request):
     assert schema['components']['schemas']['X']['properties']['x']['readOnly'] is True
     assert 'enum' in schema['components']['schemas']['XEnum']
     assert schema['components']['schemas']['XEnum']['type'] == 'integer'
+
+
+def test_viewset_list_with_envelope(no_warnings):
+    class XSerializer(serializers.Serializer):
+        x = serializers.IntegerField()
+
+    def enveloper(serializer_class, list):
+        @extend_schema_serializer(many=False)
+        class EnvelopeSerializer(serializers.Serializer):
+            status = serializers.BooleanField()
+            data = XSerializer(many=list)
+
+            class Meta:
+                ref_name = 'Enveloped{}{}'.format(
+                    serializer_class.__name__.replace("Serializer", ""),
+                    "List" if list else "",
+                )
+        return EnvelopeSerializer
+
+    class XViewset(mixins.ListModelMixin, mixins.RetrieveModelMixin, viewsets.GenericViewSet):
+        @extend_schema(responses=enveloper(XSerializer, True))
+        def list(self, request, *args, **kwargs):
+            return super().list(request, *args, **kwargs)  # pragma: no cover
+
+        @extend_schema(
+            responses=enveloper(XSerializer, False),
+            parameters=[OpenApiParameter('id', int, OpenApiParameter.PATH)],
+        )
+        def retrieve(self, request, *args, **kwargs):
+            return super().retrieve(request, *args, **kwargs)  # pragma: no cover
+
+    schema = generate_schema('x', viewset=XViewset)
+
+    operation_list = schema['paths']['/x/']['get']
+    assert operation_list['operationId'] == 'x_list'
+    assert get_response_schema(operation_list)['$ref'] == '#/components/schemas/EnvelopedXList'
+
+    operation_retrieve = schema['paths']['/x/{id}/']['get']
+    assert operation_retrieve['operationId'] == 'x_retrieve'
+    assert get_response_schema(operation_retrieve)['$ref'] == '#/components/schemas/EnvelopedX'