adding create_list to dbmongo

Change-Id: I72cd3035752d0d053586e966d6f1a5611f60fc09
Signed-off-by: tierno <alfonso.tiernosepulveda@telefonica.com>
diff --git a/osm_common/dbbase.py b/osm_common/dbbase.py
index 614fa29..7a98c76 100644
--- a/osm_common/dbbase.py
+++ b/osm_common/dbbase.py
@@ -137,10 +137,20 @@
         Add a new entry at database
         :param table: collection or table
         :param indata: content to be added
-        :return: database id of the inserted element. Raises a DbException on error
+        :return: database '_id' of the inserted element. Raises a DbException on error
         """
         raise DbException("Method 'create' not implemented")
 
+    def create_list(self, table, indata_list):
+        """
+        Add several entries at once
+        :param table: collection or table
+        :param indata_list: list of elements to insert. Each element must be a dictionary.
+            An '_id' key based on random uuid is added at each element if missing
+        :return: list of inserted '_id's. Exception on error
+        """
+        raise DbException("Method 'create_list' not implemented")
+
     def set_one(self, table, q_filter, update_dict, fail_on_empty=True, unset=None, pull=None, push=None):
         """
         Modifies an entry at database