I've been working on a tricky bug for a client at Unabridged Software where data records are getting created over and over somewhere in the code, and I'm having trouble figuring out where. I want to store the stack trace for what line of code caused a record of a particular model to be created. Enter, PaperTrail!

I couldn't have added the stack traces without the helpful hints provided by this old blog post on RubyRailsExpert.com. But, that version refers to PaperTrail version 3+, and PaperTrail is now on v12! So a few things needed to be tweaked.

Here's what I did.

1. Install PaperTrail following the instructions in the readme.

2. Add a migration to add a stack field to the PaperTrail versions column.

class AddStackToPapertrail < ActiveRecord::Migration[5.2]
  def change
    add_column :versions, :stack, :text, null: true
  end
end

3. Create a file at app/models/paper_trail_version_extensions with the methods I want. (You could also add these methods directly in the place we're about to reference them from, if you wanted.)

module PaperTrailVersionExtensions

  def get_stack 
    YAML::load(stack)
  end

  def print_stack
    get_stack.each do |entry|
      puts "  * #{entry}"
    end
  end
end

4. In config/initializers/paper_trail.rb, open up the PaperTrail::Version class like this:

module PaperTrail
  class Version < ActiveRecord::Base # Cannot use ApplicationRecord here so you may need to disable Rubocop for this line with `rubocop:disable Rails/ApplicationRecord`.

    include PaperTrail::VersionConcern

    # this is the file we created; you could also add get_stack and print_stack directly here
    include PaperTrailVersionExtensions
  end
end

5. Finally, in the model class that you want to use PaperTrail with and have stack traces, include a meta option for the stack like this:

has_paper_trail meta: { stack: :get_stack }

Now you should be able to see the stack traces for new versions created by PaperTrail by calling version.get_stack or version.print_stack.

Hope this helps!