I want to apply the len(one2many_field) in Search method of ORM. Like this search(..,order = "len(one2many_field)",..) .I want to order the result by finding total number of their children. The one2many field is in the relation to the same table. Presently I am not able to use len() in order.

Example :

 id    name    parent_id
  1     A       - 
  2     B       1 
  3     C       1 
  4     D       - 
  5     E       4

Result :

A
D