Conditionally include elements_datatypes when serializing collections

Only requests with a particular media type (used by the history UI) will include this additional field for dataset collections.

lib/galaxy/webapps/galaxy/services/history_contents.py

@@ -971,6 +971,7 @@ class HistoriesContentsService(ServiceBase):
                 f"Invalid filter found. When requesting stats, please avoid filtering by {non_orm_filter_keys}"
             )
 
+        serialization_params = self._handle_extra_serialization_for_media_type(serialization_params, accept)
         filter_query_params.order = filter_query_params.order or "hid-asc"
         order_by = self.build_order_by(self.history_contents_manager, filter_query_params.order)
         contents = self.history_contents_manager.contents(
@@ -999,6 +1000,18 @@ class HistoriesContentsService(ServiceBase):
             return HistoryContentsWithStatsResult.construct(contents=items, stats=stats)
         return HistoryContentsResult.construct(__root__=items)
 
+    def _handle_extra_serialization_for_media_type(
+        self,
+        serialization_params: SerializationParams,
+        request_media_type: str,
+    ) -> SerializationParams:
+        """According to the requested media type the response may include extra information."""
+        if request_media_type == HistoryContentsWithStatsResult.__accept_type__:
+            if not serialization_params.keys:
+                serialization_params.keys = []
+            serialization_params.keys.append("elements_datatypes")
+        return serialization_params
+
     def _serialize_legacy_content_item(
         self,
         trans,

lib/galaxy_test/api/test_history_contents.py

@@ -1138,6 +1138,20 @@ class HistoryContentsApiBulkOperationTestCase(ApiTestCase):
                 )
                 self._assert_status_code_is(response, 400)
 
+    def test_index_with_stats_has_extra_serialization(self):
+        expected_extra_keys_in_collections = ["elements_datatypes"]
+        with self.dataset_populator.test_history() as history_id:
+            self._create_collection_in_history(history_id)
+            response = self._get_contents_with_stats(
+                history_id,
+                search_query="&q=history_content_type-eq&qv=dataset_collection",
+            )
+            self._assert_status_code_is(response, 200)
+            contents_with_stats = response.json()
+            assert contents_with_stats["contents"]
+            collection = contents_with_stats["contents"][0]
+            self._assert_has_keys(collection, *expected_extra_keys_in_collections)
+
     def _get_contents_with_stats(self, history_id: str, search_query: str = ""):
         headers = {"accept": "application/vnd.galaxy.history.contents.stats+json"}
         search_response = self._get(f"histories/{history_id}/contents?v=dev{search_query}", headers=headers)