Paperclip polymorphic styles problem

I made my model Picture polymorphic and this model use paperclip. Now I
want to specify :styles for the model that have many pictures, but I
can’t find a solution to fix this. At the moment I use this and all is
working good :

But for example for model Brand I need different styles then for model

I tried a lambda like this :

:styles => lambda{|data| data.instance.picturable.attachment_styles}

But that is not a solution because it seems that link between the model
is not set when firing submit, he first do has_attached_file stuff and
then the inserting in the database, it means that showing the objects is
no problem but creating. He doesn’t know the object jet, you can find
console output here :