Hello there,
I’ve also posted this problem at the hmp forum @
http://rubyforge.org/forum/forum.php?thread_id=22433&forum_id=16450
but since this group has some higher traffic, maybe the one or another
can help me here, too.
I have a little rails (2.0.2) app with very few models so far, one
being a user model which has_many text_snippets and also has_many
bookmarks. Resources wise, these two are nested under the users … so
callable via /users/1/bookmarks/15 etc.
I ran the hmp tagging generator with the two models Bookmark and
Textsnippet which led to this entry in the tag.rb file:
has_many_polymorphs :taggables,
:from => [:bookmarks, :text_snippets],
:through => :taggings,
:dependent => :destroy,
:skip_duplicates => false,
:parent_extend => proc {
# Defined on the taggable models, not on Tag itself. Return the
tagnames associated with this record as a string.
def to_s
self.map(&:name).sort.join(Tag::DELIMITER)
end
}
So far so good. However, when starting the server, this is being
logged:
** has_many_polymorphs: rails environment detected
** has_many_polymorphs: loaded ok
** has_many_polymorphs: autoload hook invoked
** has_many_polymorphs: preloading parent model Tag
** has_many_polymorphs: associating Tag.taggables
** has_many_polymorphs: Tag could not be preloaded:
#<ActiveRecord::Associations::PolymorphicError: Could not find a valid
class for :bookmarks. If it’s namespaced, be sure to specify it
as :“module/bookmarks” instead.>
** has_many_polymorphs: preloading parent model Tagging
** has_many_polymorphs: autoload hook invoked
** has_many_polymorphs: preloading parent model Tag
** has_many_polymorphs: associating Tag.taggables
SQL (0.028267) SET NAMES ‘utf8’
SQL (0.010828) SET SQL_AUTO_IS_NULL=0
Bookmark Columns (0.103882) SHOW FIELDS FROM bookmarks
Tagging Columns (0.018256) SHOW FIELDS FROM taggings
TextSnippet Columns (0.019460) SHOW FIELDS FROM text_snippets
** has_many_polymorphs: preloading parent model Tagging
Now neither the text_snippets nor the bookmarks are taggable (double-
checked via console). However, this error is somewhat misleading
or … well… dunno… the Bookmark class does in fact exist:
Loading development environment (Rails 2.0.2)
Bookmark.inspect
=> “Bookmark(id: integer, user_id: integer, url: string, title:
string, description: text, created_at: datetime, updated_at:
datetime)”
I am really kind of confused now where to start digging/looking…
tried all I could, double-checked whether bookmarks’ files are all
correct… which they are… but still it ain’t working.
Has anyone else come across this somewhere/somehow? Any ideas/
suggestions? 
-J