ActsAsHasDefault

This acts_as extension provides the capabilities for selecting default model. The class that has this specified needs to have a default column defined as a boolean on the mapped database table.

In your Gemfile:

gem 'acts_as_has_default'

At first, you need to add a default column to desired table:

rails g migration AddDefaultToAddress default:boolean
rake db:migrate

After that you can use acts_as_has_default method in the model:

class Customer < ActiveRecord::Base
  has_many :addresses
end
    
class Address < ActiveRecord::Base
  belongs_to :customer
  acts_as_has_default scope: :customer_id
end