From 67e5d9452a49f4dee2c3010d0f74f925e4a11b6d Mon Sep 17 00:00:00 2001
From: Placido Fernandez Declara <placido.fernandez@cern.ch>
Date: Tue, 13 Jul 2021 20:05:46 +0200
Subject: [PATCH] add get CellID String from DataHandle

---
 k4FWCore/include/k4FWCore/DataHandle.h   | 26 ++++++++++++++++++++++++
 k4FWCore/include/k4FWCore/PodioDataSvc.h |  1 +
 2 files changed, 27 insertions(+)

diff --git a/k4FWCore/include/k4FWCore/DataHandle.h b/k4FWCore/include/k4FWCore/DataHandle.h
index 8f8e9af2..563d5eae 100644
--- a/k4FWCore/include/k4FWCore/DataHandle.h
+++ b/k4FWCore/include/k4FWCore/DataHandle.h
@@ -41,6 +41,9 @@ class DataHandle : public DataObjectHandle<DataWrapper<T>> {
 
   T* put( std::unique_ptr<T> object );
 
+  ///Retrieve CellID string from the Collection metadata
+  const std::string getCollMetadataCellID(const unsigned int id);
+
   /**
   * Create and register object in transient store
   */
@@ -170,6 +173,7 @@ void DataHandle<T>::put(T* objectp) {
 
 }
 
+
 //---------------------------------------------------------------------------
 template <typename T>
 T* DataHandle<T>::put( std::unique_ptr<T> objectp ){
@@ -177,6 +181,28 @@ T* DataHandle<T>::put( std::unique_ptr<T> objectp ){
   return objectp.release();
 }
 
+
+//---------------------------------------------------------------------------
+// Get the CellID encoded String from the Metadata of the collection
+// using Podio Data Service
+// Give collection ID
+template <typename T>
+const std::string DataHandle<T>::getCollMetadataCellID(
+  const unsigned int id)
+{
+  PodioDataSvc* pds;
+  pds = dynamic_cast<PodioDataSvc*>( m_eds.get());
+
+  if (pds != nullptr) {
+    auto colMD = pds->getProvider().getCollectionMetaData( id );
+    return colMD.getStringVal("CellIDEncodingString") ;
+  } else {
+    std::string msg("Could not get Podio Data Service.");
+    throw GaudiException(msg, "Failed to get Collection Metadata.", StatusCode::FAILURE);
+  }
+}
+
+
 //---------------------------------------------------------------------------
 /**
  * Create the collection, put it in the DataObjectHandle and return the
diff --git a/k4FWCore/include/k4FWCore/PodioDataSvc.h b/k4FWCore/include/k4FWCore/PodioDataSvc.h
index 7132d803..a26d33f8 100644
--- a/k4FWCore/include/k4FWCore/PodioDataSvc.h
+++ b/k4FWCore/include/k4FWCore/PodioDataSvc.h
@@ -43,6 +43,7 @@ class PodioDataSvc : public DataSvc {
 
   virtual const CollRegistry& getCollections() const { return m_collections; }
   virtual const CollRegistry& getReadCollections() const { return m_readCollections; }
+  const podio::EventStore& getProvider() const { return m_provider; }
   virtual podio::CollectionIDTable* getCollectionIDs() { return m_collectionIDs; }
 
   /// Set the collection IDs (if reading a file)