Princess Pigsty by Cornelia Funke

From chapters.ca:
One morning Princess Isabella throws her crown out the window--it's BORING being a princess, she declares. When she steadfastly refuses to fetch her crown from the fishpond, her father, the king, puts his royal foot down. "Off to the pigsty with you!" he commands--and Isabella couldn't be happier about her punishment! Because while plain old princesses spend all their time primping and smiling and stifling yawns--yuckety-yuk!-- REAL girls get to peel onions, pick blackberries, and sometimes even sleep outside with the pigs.

Originally in German.