DB view migration wrapper using Scenic

20180207210749_convert_film_ids_to_strings.rb

require 'migration/rebuild'

class ConvertFilmIdsToStrings < ActiveRecord::Migration[5.1]
  include Migration::Rebuild

  EVENT_VIEWS = {
    # view:              version
    eventbase_events:    26,
    eventbase_entities:  34,
    admin_entity_stats:  8,
    facebook_events:     5
  }

  def up
    rebuild(EVENT_VIEWS) do
      remove_foreign_key :screenings, :films
      change_column :films, :id, :string
      change_column :screenings, :film_id, :string
      add_foreign_key :screenings, :films
    end
  end

  def down
    rebuild(EVENT_VIEWS) do
      remove_foreign_key :screenings, :films
      change_column :films, :id, :integer, using: 'id::integer'
      change_column :screenings, :film_id, :integer, using: 'id::integer'
      add_foreign_key :screenings, :films
    end
  end
end

rebuild.rb

module Migration
  module Rebuild
    def rebuild(views=[])
      views.each {|view, version| drop_view view}
      yield
      views.each {|view, version| create_view view, version: version}
    end
  end
end