Rails destroy all but newest n records

Question

How do I destroy all but the newest n records using Rails\' ActiveRecord?

I can get the newest n records using order and limit but how do I destroy the inverse?

Answer 1

I have two methods of doing this, assuming n = 5:

Foo.order('id desc').offset(5).destroy_all

This sorts records with latest first, and destroys everything past the 5th records. Or

Foo.destroy_all(['id <= ?', Foo.order('id desc').limit(1).offset(5).first.id])

This finds the 6th latest record id and deletes all records with id <= 6th latest record id.

Also, you might want to look at this SO question.