class ActiveRecord::ConnectionAdapters::SchemaCreation

def action_sql(action, dependency)
  case dependency
  when :nullify then "ON #{action} SET NULL"
  when :cascade  then "ON #{action} CASCADE"
  when :restrict then "ON #{action} RESTRICT"
  else
    raise ArgumentError, <<~MSG
      '#{dependency}' is not supported for :on_update or :on_delete.
      Supported values are: :nullify, :cascade, :restrict
    MSG
  end
end