From eab2e2be6f00af7b2ce0fb659239abf0c5901e90 Mon Sep 17 00:00:00 2001
From: tmadlener <thomas.madlener@desy.de>
Date: Fri, 30 Jun 2023 14:56:32 +0200
Subject: [PATCH 1/2] Only create an internal pointer if necessary

---
 k4FWCore/include/k4FWCore/DataHandle.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/k4FWCore/include/k4FWCore/DataHandle.h b/k4FWCore/include/k4FWCore/DataHandle.h
index 8485fe54..8a21e8ae 100644
--- a/k4FWCore/include/k4FWCore/DataHandle.h
+++ b/k4FWCore/include/k4FWCore/DataHandle.h
@@ -77,7 +77,9 @@ DataHandle<T>::DataHandle(const std::string& descriptor, Gaudi::DataHandle::Mode
 
     podio_data_service = dynamic_cast<PodioDataSvc*>(m_eds.get());
     if (nullptr != podio_data_service) {
-      m_dataPtr = new T();
+      if constexpr (std::is_integral_v<T> || std::is_floating_point_v<T>) {
+        m_dataPtr = new T();
+      }
     } else {
       // This is the legacy implementation kept for a transition period
       PodioLegacyDataSvc* plds;

From f97890a3e6d89b40b6bd22ebf3686a82759e5930 Mon Sep 17 00:00:00 2001
From: tmadlener <thomas.madlener@desy.de>
Date: Mon, 3 Jul 2023 17:19:16 +0200
Subject: [PATCH 2/2] Revive cellID functionality for legacy data svc

---
 k4FWCore/include/k4FWCore/DataHandle.h | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/k4FWCore/include/k4FWCore/DataHandle.h b/k4FWCore/include/k4FWCore/DataHandle.h
index 8a21e8ae..99285dde 100644
--- a/k4FWCore/include/k4FWCore/DataHandle.h
+++ b/k4FWCore/include/k4FWCore/DataHandle.h
@@ -193,8 +193,13 @@ template <typename T> T* DataHandle<T>::createAndPut() {
 
 // Temporary workaround for k4MarlinWrapper
 template <typename T> const std::string DataHandle<T>::getCollMetadataCellID(const unsigned int id) {
-  std::cerr << "k4FWCore: getCollMetadataCellID is not implemented!" << std::endl;
-  return "";
+  if (auto lpds = dynamic_cast<PodioLegacyDataSvc*>(m_eds.get())) {
+    auto colMD = lpds->getProvider().getCollectionMetaData(id);
+    return colMD.getValue<std::string>("CellIDEncodingString");
+  }
+
+  throw GaudiException("getCollMetadataCellID is only implemented for the legacy data svc",
+                       "Cannot get collection metadata", StatusCode::FAILURE);
 }
 
 // temporary to allow property declaration