Added 'getCreatorId()' method for VOSpace nodes.

Signed-off-by: Cristiano Urban <cristiano.urban@inaf.it>

transfer_service/db_connector.py

@@ -67,6 +67,25 @@ class DbConnector(object):
         else:
             return False
 
+    def getCreatorId(self, vospacePath):
+        """Returns the creator ID for a given vospace path representing a node."""
+        with self.getConnection() as conn:
+            try:
+                cursor = conn.cursor(cursor_factory = RealDictCursor)
+                cursor.execute("""
+                    SELECT creator_id
+                    FROM node_vos_path nvp
+                    JOIN node n ON nvp.node_id = n.node_id
+                    WHERE vos_path = %s;
+                    """, 
+                    (vospacePath,))
+                result = cursor.fetchall()
+            except Exception as e:
+                if not conn.closed:
+                    conn.rollback()
+                print(e)
+        return result[0]["creator_id"]
+
     def getOSPath(self, vospacePath):
         """Returns a list containing full path, storage type and username for a VOSpace path."""
         with self.getConnection() as conn: