Migration for a model that does not exist in the app

migration.rb

class MyMigrationForSomething < ActiveRecord::Migration
  class Monologue::PostsRevision < ActiveRecord::Base
  end

  def up
    Monologue::PostsRevision.reset_column_information # This might not be necessary, but you know it exists if needed! :)
    # do your stuff here...
  end

  def down
  	Monologue::PostsRevision.reset_column_information
  end

  # or, depending on what your migration does, just this 'change' method instead of both 'up' and 'down' methods
  def change
  	Monologue::PostsRevision.reset_column_information
  end
 end