Cache response, return success on repeat request

src/purchase/tests/test_send_rsc.py

@@ -247,10 +247,11 @@ def test_repeat_request_support_comment_distribution(self):
         self.assertContains(response, "id", status_code=201)
 
         # make a second request with the same client_id which should fail.
-        response = self._post_support_response(
+        response_repeat_call = self._post_support_response(
             user, comment.id, client_id, "rhcommentmodel", tip_amount
         )
-        self.assertEqual(response.status_code, 400)
+        self.assertEqual(response.data, response_repeat_call.data)
+        self.assertEqual(response_repeat_call.status_code, 201)
 
     def _post_support_response(
         self, user, object_id, client_id, content_type, amount=10

src/purchase/views/purchase_view.py

@@ -78,17 +78,13 @@ def create(self, request):
         with transaction.atomic():
             user = User.objects.select_for_update().get(id=user.id)
 
-            cached_client_id = cache.get(f"purchase_client_id_{client_id}")
-            if cached_client_id:
+            cached_serialized_data = cache.get(f"purchase_client_id_{client_id}")
+            if cached_serialized_data:
                 return Response(
-                    {
-                        "detail": "This purchase has already been processed",
-                    },
-                    status=400,
+                    cached_serialized_data,
+                    status=201,
                 )
 
-            cache.set(f"purchase_client_id_{client_id}", True, timeout=60)
-
             purchase_data = {
                 "amount": amount,
                 "user": user.id,
@@ -219,6 +215,8 @@ def create(self, request):
         serializer = self.serializer_class(purchase, context=context)
         serializer_data = serializer.data
 
+        cache.set(f"purchase_client_id_{client_id}", serializer_data, timeout=3600)
+
         if recipient and user:
             self.send_purchase_notification(
                 purchase, unified_doc, recipient, notification_type