Set version limit per model in Papertrail?

Question

Is there a way to limit the number of versions, per model, in Papertrail?

E.g., I know I can set a global limit with

PaperTrail.config.version_limit = 3

But I don't see a way to set that per model, with something like

class Article < ActiveRecord::Base
  has_paper_trail :limit => [10]
end

I also don't want to just limit the number of versions saved (to say ten) but have it so only the latest ten are saved (same as with the config version setting).

Answer 1

Here is the answer you want:

Add constant "PAPER_TRAIL_VERSION_LIMIT" to your Article model like below

# models/article.rb
class Article < ActiveRecord::Base
  has_paper_trail
  # 10 mean you article will have 11 version include 'create' version
  PAPER_TRAIL_VERSION_LIMIT = 10
end

Add below codes to the bottom of PaperTrail config file

# /config/initializers/paper_trail.rb
module PaperTrail
  class Version < ActiveRecord::Base
    private
    def enforce_version_limit!
      limit = PaperTrail.config.version_limit
      # This is the key custom line
      limit = item.class::PAPER_TRAIL_VERSION_LIMIT  if item.class.const_defined?("PAPER_TRAIL_VERSION_LIMIT")
      return unless limit.is_a? Numeric
      previous_versions = sibling_versions.not_creates
      return unless previous_versions.size > limit
      excess_versions = previous_versions - previous_versions.last(limit)
      excess_versions.map(&:destroy)
    end
  end
end

Enjoy it ! :D