activerecord - Ruby on rails active record: update a field by another field in the same record using update_all -

how can use update_all following purpose:

update  table_name set field1=field2 * 2 id = 1 

in rails4, can do

model.where(id: 1).update_all("field = field2 * 2") 

in previous versions of rails, can pass condition update_all, this

model.update_all("field = field2 * 2", {:id => 1}) 

note:

update_all not trigger active record callbacks or validations