I'm running from the source version 1.99.4 from my own python 2.7
installation,
Model Code
db = DAL("sqlite://storage.sqlite")
db.define_table('image',
Field('title', unique=True),
Field('file', 'upload'),
format = '$(title)s')
db.define_table('comment',
Field('image_id', db.image),
Field('author'),
Field('email'),
Field('body', 'text'))
db.image.title.requires = IS_NOT_IN_DB(db, db.image.title)
db.comment.image_id.requires = IS_IN_DB(db, db.image.id, '%(title)s')
db.comment.author.requires = IS_NOT_EMPTY()
db.comment.email.requires = IS_EMAIL()
db.comment.body.requires = IS_NOT_EMPTY()
db.comment.image_id.writable = db.comment.image_id.readable = False
