Rails migration helper code for updating model concern-specific columns

concern_helper.rb

# Helper methods for writing migrations for concern specific things.
module ConcernHelper

  # Returns an array of symbols containing the table names of all models
  # including 'concern'. If a block is given, it's called for each table name.
  #
  # Example usage:
  # class AddSomethingToAllFooables
  #   include ConcernHelper
  #
  #   def change
  #     each_including_concern Fooable do |table|
  #       add_column table, :something, :string
  #     end
  #   end
  # end
  #
  def each_including_concern(concern, &block)
    Rails.application.eager_load!

    symbols = ActiveRecord::Base.descendants
      .select{|klass| klass.superclass == ActiveRecord::Base}
      .select{|klass| klass.include? concern}
      .map(&:table_name).map(&:to_sym)

    symbols.each(&block) if block_given?
    symbols
  end

  # Delegate helper to check if a certain table already has a certain column.
  def column_exists?(table, column)
    ActiveRecord::Base.connection.column_exists? table, column
  end
end