--- UserCode/MitProd/TreeFiller/interface/BaseFiller.h	2008/07/07 16:14:01	1.7
+++ UserCode/MitProd/TreeFiller/interface/BaseFiller.h	2008/07/30 08:39:50	1.10
@@ -1,5 +1,5 @@
 //--------------------------------------------------------------------------------------------------
-// $Id: BaseFiller.h,v 1.7 2008/07/07 16:14:01 loizides Exp $
+// $Id: BaseFiller.h,v 1.10 2008/07/30 08:39:50 loizides Exp $
 //
 // BaseFiller
 //
@@ -12,9 +12,12 @@
 #define TREEFILLER_BASEFILLER_H
 
 #include "FWCore/Framework/interface/Event.h"
-#include "FWCore/ParameterSet/interface/ParameterSet.h"
 #include "FWCore/Framework/interface/Frameworkfwd.h"
+#include "FWCore/ParameterSet/interface/ParameterSet.h"
+#include "FWCore/MessageLogger/interface/MessageLogger.h"
+#include "DataFormats/Common/interface/Handle.h"
 #include "MitAna/DataUtil/interface/TreeWriter.h"
+#include <TString.h>
 
 namespace mithep 
 {
@@ -32,10 +35,34 @@ namespace mithep
 
     protected:
       const edm::ParameterSet &Conf()   const { return config_; }
-
-      const std::string        name_;    //name of this filler
-      const edm::ParameterSet  config_;  //parameter set for this filler
-      const bool               active_;  //=1 if active
+      void                     PrintErrorAndExit(const char *msg) const;
+      template <typename TYPE>
+      void                     GetProduct(const std::string name, edm::Handle<TYPE> &product,
+                                          const edm::Event &event) const;    
+
+      const std::string        name_;    // name of this filler
+      const edm::ParameterSet  config_;  // parameter set for this filler
+      const bool               active_;  // =1 if active
   };
 }
+
+//--------------------------------------------------------------------------------------------------
+template <typename TYPE>
+inline void mithep::BaseFiller::GetProduct(const std::string edmname, edm::Handle<TYPE> &product,
+                                           const edm::Event &event) const
+{
+  // Try to access data collection from EDM file. We check if we really get just one
+  // product with the given name. If not we print an error and exit.
+
+  try {
+    event.getByLabel(edm::InputTag(edmname),product);
+    if (!product.isValid()) 
+      throw edm::Exception(edm::errors::Configuration, "BaseFiller::GetProduct()\n")
+        << "Cannot get collection with label " << edmname << std::endl;
+  } catch (...) {
+    edm::LogError("BaseFiller") << "Cannot get collection with label "
+                                << edmname << std::endl;
+    PrintErrorAndExit(Form("Cannot get collection with label %s", edmname.c_str()));
+  }
+}
 #endif