Module which provides the ability to unscope associations

unscoped.rb

# Provides the ability to unscope associations, this solves problems described in
# http://stackoverflow.com/questions/1540645/how-to-disable-default-scope-for-a-belongs-to/11012633#11012633
#
# Examples
#
#    class Document < ActiveRecord::Base
#      default_scope where(deleted: false)
#    end
#
#    class Comment < ActiveRecord::Base
#      extend Unscoped
#
#      belongs_to :document
#      unscope :document
#    end
#
module Unscoped

  # Public: Ensure a previously defined association is not scoped by a default_scope.
  #
  # associations - The Symbol with the name(s) of the associations to unscope.
  #
  # Examples
  #
  #    # Unscope a single assoication
  #    unscope :document
  #
  #    # Unscope multiple in one way.
  #    unscope :document, :comments
  #
  # Raises ArgumentError if the named association does not exist on the model, so ensure
  # the association is defined _before_ calling `unscope`.
  #
  # Returns nothing.
  def unscope(*associations)
    associations.flatten.each do |association|
      raise ArgumentError, "no association named #{association} exists on this model" unless self.reflect_on_association(*association)
  
      class_eval <<-RUBY, __FILE__, __LINE__ + 1
        def #{association}
          self.class.reflect_on_association(#{association.inspect}).klass.unscoped { super }
        end
      RUBY
    end
  end
end

Still works with rails 6.1
A-mazing!

PS: Not sure if it will break anything else :D

Haha, wow, this is indeed amazing. Power of Rails. 👍

PS: I just tried to remember where I've required this, as this bit was written ages ago.

Still relevant and useful in Rails 7.2 (and probably 8 too).
I made it a concern:

# Provides the ability to unscope associations, this solves problems described in
# http://stackoverflow.com/questions/1540645/how-to-disable-default-scope-for-a-belongs-to/11012633#11012633
#
# Examples
#
#    class Document < ActiveRecord::Base
#      default_scope where(deleted: false)
#    end
#
#    class Comment < ActiveRecord::Base
#      include Unscoped
#
#      belongs_to :document
#      unscope :document
#    end
#
module Unscoped

  extend ActiveSupport::Concern

  class_methods do
    # Public: Ensure a previously defined association is not scoped by a default_scope.
    #
    # associations - The Symbol with the name(s) of the associations to unscope.
    #
    # Examples
    #
    #    # Unscope a single assoication
    #    unscope :document
    #
    #    # Unscope multiple in one way.
    #    unscope :document, :comments
    #
    # Raises ArgumentError if the named association does not exist on the model, so ensure
    # the association is defined _before_ calling `unscope`.
    #
    # Returns nothing.
    def unscope(*associations)
      associations.flatten.each do |association|
        unless reflect_on_association(*association)
          raise ArgumentError,
                "no association named #{association} exists on this model"
        end

        class_eval <<-RUBY, __FILE__, __LINE__ + 1
          # def document
          #   self.class.reflect_on_association(:document).klass.unscoped { super }
          # end

          def #{association}
            self.class.reflect_on_association(#{association.inspect}).klass.unscoped { super }
          end
        RUBY
      end
    end
  end

end