Error with Single Table Inheritance

[sreuterle]

I'm using paper_trail 4.0.2 with ruby 2.3.0, rails 4.2.6. I want to update to latest version of paper_trail (4.1.0).
With new version running I can't refer to self.version from within a module.

I encapsulated history related stuff into a ActiveSupport::Concern for my model 'User':

class User < Person
  include UserHistory
  ...
end

module UserHistory
  extend ActiveSupport::Concern

  included do
    has_paper_trail :skip => [:updated_at, :created_at, :remember_created_at, :sign_in_count, :current_sign_in_at, :last_sign_in_at, :current_sign_in_ip, :last_sign_in_ip, :failed_attempts]
  end
  ...

  def was_attribute_changed?(attribute_name)
    (!is_just_created? && !last_changeset[attribute_name.to_sym].blank?)
  end

  def last_changeset
    @last_changeset ||= self.versions.last.changeset
  end
  ...
end

Calling was_attribute_changed? on a User instance (no problem) refers to the method last_changeset within the same module (no problem too). This calls the PaperTrail method versions but gets an error:

undefined method 'versions' for UserHistory:Module

This error only occurs with version 4.1.0 of paper_trail but not with 4.0.2. It occurs with both rails 4.2.6 and 4.2.5
Is there any change regarding that? Is it a feature or is it a bug?

I don't know how to use your template for reporting bugs, sorry.

[jaredbeck]

I can't reproduce this issue. Here's what I tried: https://gist.github.com/jaredbeck/122239d2e62717f44808 What are we doing differently?

[sreuterle]

Hi and sorry for being so late with my answer, I was on holidays a few days.

I could now isolate the the issue a way better. I edited your code sample so that the error is more visible. It seems to be an issue with Single Table Inheritance - nothing to do with calling self.* as I thought first:
https://gist.github.com/sreuterle/7de97c87741fe1da422a34c9bae1701d

You can switch paper_trail version between 4.0.2 and 4.1.0

I located that in PaperTrail::VersionConcern.load_changeset an error is thrown (copied from my real application):

NoMethodError: undefined method `unserialize_attribute_changes_for_paper_trail!' for #Class:0x007fa5e0145838

/Users/sreuter/.rvm/gems/ruby-2.3.0@global/gems/activerecord-4.2.6/lib/active_record/dynamic_matchers.rb:26:in `method_missing'

/Users/sreuter/.rvm/gems/ruby-2.3.0@global/gems/paper_trail-4.1.0/lib/paper_trail/version_concern.rb:263:in `load_changeset'

/Users/sreuter/.rvm/gems/ruby-2.3.0@global/gems/paper_trail-4.1.0/lib/paper_trail/version_concern.rb:215:in `changeset'

This error usually is suppressed and rescued by returning an empty Hash.

I hope you can reproduce it now?

[jaredbeck]

I located that in PaperTrail::VersionConcern.load_changeset an error is [raised] .. This error .. is suppressed and rescued by returning an empty Hash. I hope you can reproduce it now?

Yes, I see the same error in load_changeset, undefined method unserialize_attribute_changes_for_paper_trail! for Person.

I'm not sure this is a bug though. Maybe you're supposed to include UserHistory in the parent class (Person) instead of in User? That's how it's done in our test suite (see Elephant < Animal).

[jaredbeck]

Assuming this is not a bug (see above) I'd still like to find a way to provide a better error message.

[sreuterle]

Thanks for your reply.
include UserHistory for the parent class Person is not an option because there are some more classes extending Person. We only want versioning for the class User.
The older version of paper_trail worked for this. Are the changes not able to work with such structure as before too?

[jaredbeck]

You can switch paper_trail version between 4.0.2 and 4.1.0 .. The older version of paper_trail worked ..

Oops, I didn't catch that part, sorry. So this is a regression between 4.0 and 4.1. Noted, thanks!

[jaredbeck]

To summarize, in https://gist.github.com/sreuterle/7de97c87741fe1da422a34c9bae1701d

• Reproduced with PT 4.1.0
• Cannot reproduce with PT 4.0.2

[jaredbeck]

Fixed by 23ffbdc

Sven, please try master, or wait for 5.0, which should be coming soon.

[sreuterle]

Yeah, I upgraded to 5.x and it works. Thank you very much!