Create other autoincrement field besides the id on MongoDB

[Leonardo Tada]

I know the field id is autoincrement, but I need other field besides the id, because I'm trying to use MongoDB and the field id that created is like '{ "_id" : { "$oid" : "539139c0dfe28529f6fb72cb"}'.
Then have to create other autoincrement field besides the id.
Anybody can help?

[Massimo Di Pierro]

If you use db = DAL('mongodb:...')

tables get automatically an integer "id" field. It is not auto-increment and it is stored as a UUID by mongo. web2py converts the UUID to an integer and back so that web2py does not break.

[Leonardo Tada]

I understood, but have a way to make other field like auto-increment?