Multi-step form in Rails 3 with Paperclip attachments

Question

I\'m creating a multi-part form in the style that Ryan Bates describes here:

http://railscasts.com/episodes/217-multistep-forms
http://asciicasts.com/episodes

Answer 1

Saving models into the session is working unless you want to save a File into the session. The wizard plugins are using the session to store models between the steps. They do not produce errors on valid models in my case only on invalids.

So clearing out the attached file sounded a good idea, but in my case clearing out the paperclip attachment with Attachment#clear was not enough because it still wanted to save some File.

I've found out that the problem was with the @queued_for_write attribute in Attachment which still contained the data.

So the following two lines solved my problem:

unless @model.valid?
  @model.image.clear
  @model.image.queued_for_write.clear
end

This was a paperclip bug and was corrected in this commit.