Wow, Now I see my example completely wrong.. should be
db.define_table('post',
# more fields here
Field('thoughts', "reference Thoughts")
)
db.define_table('Thoughts',
Field('Editedby', db.auth_user, default=None, readable=True,
writable=True),
Field('TitleOfPost',requires=IS_NOT_EMPTY()),
Field('ContentOfPost','text',requires=IS_NOT_EMPTY()),
Field('DatePosted','date'),
Field('DP_Large', 'upload', uploadfield='picture_file'),
Field('picture_file', 'blob'),
)
--

