Support returning more than one nextid

trytond/doc/ref/backend.rst

@@ -65,9 +65,9 @@ Database
    If ``hostname`` is set, it checks also if it has the same configured
    hostname.
 
-.. method:: Database.nextid(connection, table)
+.. method:: Database.nextid(connection, table[, count])
 
-   Return the next ID for the ``table`` using the ``connection``.
+   Return the next ``count`` IDs for the ``table`` using the ``connection``.
 
    .. note:: It may return ``None`` for some database.
 

trytond/trytond/backend/database.py

@@ -55,7 +55,7 @@ class DatabaseInterface(object):
         '''
         raise NotImplementedError
 
-    def nextid(self, connection, table):
+    def nextid(self, connection, table, count=1):
         pass
 
     def setnextid(self, connection, table, value):

trytond/trytond/backend/postgresql/database.py

@@ -414,12 +414,16 @@ class Database(DatabaseInterface):
                 pass
         return True
 
-    def nextid(self, connection, table):
+    def nextid(self, connection, table, count=1):
         cursor = connection.cursor()
         cursor.execute(
-            "SELECT nextval(pg_get_serial_sequence(format(%s, %s), %s))",
-            ('%I', table, 'id'))
-        return cursor.fetchone()[0]
+            "SELECT nextval(pg_get_serial_sequence(format(%s, %s), %s)) "
+            "FROM generate_series(1, %s)",
+            ('%I', table, 'id', count))
+        if count == 1:
+            return cursor.fetchone()[0]
+        else:
+            return [id for id, in cursor]
 
     def setnextid(self, connection, table, value):
         cursor = connection.cursor()