Add database accessor to list all patients

Allows user of this class to iterate through all contents
of the database hierarchically

Libs/DICOM/Core/ctkDICOMDatabase.cpp

@@ -265,6 +265,21 @@ void ctkDICOMDatabase::closeDatabase()
 }
 
 //------------------------------------------------------------------------------
+QStringList ctkDICOMDatabase::patients()
+{
+  Q_D(ctkDICOMDatabase);
+  QSqlQuery query(d->Database);
+  query.prepare ( "SELECT UID FROM Patients" );
+  query.exec();
+  QStringList result;
+  while (query.next()) 
+    {
+    result << query.value(0).toString();
+    }
+  return( result );
+}
+
+//------------------------------------------------------------------------------
 QStringList ctkDICOMDatabase::studiesForPatient(QString patientUID)
 {
   Q_D(ctkDICOMDatabase);

Libs/DICOM/Core/ctkDICOMDatabase.h

@@ -109,6 +109,7 @@ public:
 
   ///
   /// \brief database accessors
+  Q_INVOKABLE QStringList patients ();
   Q_INVOKABLE QStringList studiesForPatient (QString patientUID);
   Q_INVOKABLE QStringList seriesForStudy (QString studyUID);
   Q_INVOKABLE QStringList filesForSeries (QString seriesUID);