Non persistent ActiveRecord model attributes

Question

I want to add to an existing model some attributes that need not be persisted, or even mapped to a database column. Is there a solution to specify such thing ?

Answer 1

From Rails 5.0 onwards you could use attribute:

class StoreListing < ActiveRecord::Base
  attribute :non_persisted
  attribute :non_persisted_complex, :integer, default: -1
end

With attribute the attribute will be created just like the ones being persisted, i.e. you can define the type and other options, use it with the create method, etc.

If your DB table contains a matching column it will be persisted because attribute is also used to affect conversion to/from SQL for existing columns.

see: https://api.rubyonrails.org/classes/ActiveRecord/Attributes/ClassMethods.html#method-i-attribute