This type of validation is handled by validates_presence_of
.
Seems like you’re looking for
validates_presence_of :lock_version, on: :update
I strongly advise to take a look on http://apidock.com/rails/ActiveRecord/Validations/ClassMethods/validates_presence_of
There are plenty of validations in Rails and this is probably the most basic one.
http://guides.rubyonrails.org/active_record_validations.html