enable hstore in postgres (requires user to be superuser)

_enable_hstore.rb

class EnableHstore < ActiveRecord::Migration

  def up
    enable_extension :hstore
  rescue ActiveRecord::StatementInvalid => maybe_hstore_exception
    if maybe_hstore_exception.original_exception.is_a? PG::UndefinedFile
      STDERR.puts <<MSG

*****************************************************
Exception occured during enabling "hstore" extension.
If you your OS is debian/ubuntu then try to install "postgresql-contrib" package.
*****************************************************

MSG
    end

    raise maybe_hstore_exception
  end

  def down
    disable_extension :hstore
  end

end