demo_app/my_platform/db/migrate/20150505221640_add_message_id_to_posts.your_platform.rb
# This migration comes from your_platform (originally 20150505221601)
class AddMessageIdToPosts < ActiveRecord::Migration[4.2]
def change
add_column :posts, :message_id, :string
add_column :posts, :content_type, :string
end
end