Make it possible to retrieve collection names via new svc

Author: tmadlener

k4FWCore/components/CollectionFromObjectSvc.cpp

@@ -44,6 +44,17 @@ StatusCode CollectionFromObjectSvc::initialize() {
   return StatusCode::SUCCESS;
 }
 
+const std::optional<std::string> CollectionFromObjectSvc::getCollectionNameFor(const podio::ObjectID id) const {
+  debug() << "Trying to retrieve collection name for object " << id << endmsg;
+  const auto& idTable = k4FWCore::details::getTESCollectionIDTable(m_dataSvc, this);
+  auto name = idTable.name(id.collectionID);
+  if (!name.has_value()) {
+    error() << "Could not get a collection name for object " << id << endmsg;
+    return std::nullopt;
+  }
+  return name.value();
+}
+
 const podio::CollectionBase* CollectionFromObjectSvc::getCollectionFor(const podio::ObjectID id) const {
   debug() << "Trying to retrieve collection for object " << id << endmsg;
   const auto& idTable = k4FWCore::details::getTESCollectionIDTable(m_dataSvc, this);

k4FWCore/components/CollectionFromObjectSvc.h

@@ -35,6 +35,7 @@ class CollectionFromObjectSvc : public extends<Service, ICollectionFromObjectSvc
 
 protected:
   const podio::CollectionBase* getCollectionFor(const podio::ObjectID id) const override;
+  const std::optional<std::string> getCollectionNameFor(const podio::ObjectID id) const override;
 
 private:
   SmartIF<IDataProviderSvc> m_dataSvc;

k4FWCore/include/k4FWCore/ICollectionFromObjectSvc.h

@@ -25,7 +25,8 @@
 #include <podio/ObjectID.h>
 #include <podio/utilities/TypeHelpers.h>
 
-#include <fmt/format.h>
+#include <optional>
+#include <string>
 
 class ICollectionFromObjectSvc : virtual public IInterface {
 public:
@@ -36,8 +37,15 @@ class ICollectionFromObjectSvc : virtual public IInterface {
     return dynamic_cast<const typename O::collection_type*>(getCollectionFor(object.id()));
   }
 
+  // TODO: return string_view? Some form of DataHandle?
+  template <podio::ObjectType O>
+  const std::optional<std::string> getCollectionNameFor(const O& object) const {
+    return getCollectionNameFor(object.id());
+  }
+
 protected:
   virtual const podio::CollectionBase* getCollectionFor(const podio::ObjectID) const = 0;
+  virtual const std::optional<std::string> getCollectionNameFor(const podio::ObjectID) const = 0;
 };
 
 #endif

test/k4FWCoreTest/src/components/TestCollectionFromObjectRetrieval.cpp

@@ -43,7 +43,17 @@ struct TestCollectionFromObjectRetrieval final : k4FWCore::Consumer<void(const e
       throw std::runtime_error("Could not get the expected collection from the object");
     }
 
+    const auto name = m_collFromObjSvc->getCollectionNameFor(mc);
+    if (name.value() != inputLocations(0)[0]) {
+      throw std::runtime_error("Collection name retrieved via object of collection is not as expected");
+    }
+
     auto newMCParticle = edm4hep::MutableMCParticle{};
+    const auto invalidName = m_collFromObjSvc->getCollectionNameFor(newMCParticle);
+    if (invalidName.has_value()) {
+      throw std::runtime_error("Retrieved a name for an object that is not known to the TES");
+    }
+
     const auto* invalidColl = m_collFromObjSvc->getCollectionFor(newMCParticle);
     if (invalidColl) {
       throw std::runtime_error("Could get a collection for an object that is not in a collection");