Isolate paper_trail

decidim-accountability/app/models/decidim/accountability/result.rb

@@ -11,11 +11,10 @@ class Result < Accountability::ApplicationRecord
       include Decidim::HasCategory
       include Decidim::HasReference
       include Decidim::Comments::Commentable
+      include Decidim::Traceable
 
       feature_manifest_name "accountability"
 
-      has_paper_trail
-
       has_many :children, foreign_key: "parent_id", class_name: "Decidim::Accountability::Result", inverse_of: :parent, dependent: :destroy
       belongs_to :parent, foreign_key: "parent_id", class_name: "Decidim::Accountability::Result", inverse_of: :children, optional: true, counter_cache: :children_count
 

decidim-core/app/helpers/decidim/traceability_helper.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 module Decidim
-  # A Helper to render and link to resources.
+  # A Helper to find and render the author of a version.
   module TraceabilityHelper
     # Renders the avatar and author name of the author of the last version of the given
     # resource.

decidim-core/app/services/decidim/traceability.rb

@@ -0,0 +1,73 @@
+# frozen_string_literal: true
+
+module Decidim
+  # This class wraps the logic to trace resource changes and their authorship.
+  # It is expected to be used with classes implementing the `Decidim::Traceable`
+  # concern. Version authors can be retrieved using the methods in
+  # `Decidim::TraceabilityHelper`.
+  #
+  # Examples:
+  #
+  #     # consider MyResource implements Decidim::Traceable
+  #     resource = Decidim::Traceability.new.create!(MyResource, author, params)
+  #     resource.versions.count # => 1
+  #     resource.versions.last.whodunnit # => author.to_gid.to_s
+  #     resource.versions.last.event # => "create"
+  #     resource = Decidim::Traceability.new.update!(resource, author, params)
+  #     resource.versions.count # => 2
+  #     resource.versions.last.event # => "update"
+  #
+  # This class uses the `paper_trail` gem internally, so refer to its documentation
+  # for further info on how to interact with versions.
+  class Traceability
+    # Calls the `create` method to the given class and sets the author of the version.
+    #
+    # klass - An ActiveRecord class that implements `Decidim::Traceable`
+    # author - An object that implements `to_gid` or a String
+    # params - a Hash
+    #
+    # Returns an instance of `klass`.
+    def create(klass, author, params)
+      PaperTrail.whodunnit(gid(author)) do
+        klass.create(params)
+      end
+    end
+
+    # Calls the `create!` method to the given class and sets the author of the version.
+    #
+    # klass - An ActiveRecord class that implements `Decidim::Traceable`
+    # author - An object that implements `to_gid` or a String
+    # params - a Hash
+    #
+    # Returns an instance of `klass`.
+    def create!(klass, author, params)
+      PaperTrail.whodunnit(gid(author)) do
+        klass.create!(params)
+      end
+    end
+
+    # Updates the `resource` with `update_attributes!` and sets the author of the version.
+    #
+    # resource - An ActiveRecord instance that implements `Decidim::Traceable`
+    # author - An object that implements `to_gid` or a String
+    # params - a Hash
+    #
+    # Returns the updated `resource`.
+    def update!(resource, author, params)
+      PaperTrail.whodunnit(gid(author)) do
+        resource.update_attributes!(params)
+        resource
+      end
+    end
+
+    private
+
+    # Calculates the GlobalID of the version author. If the object does not respond to
+    # `to_gid`, then it returns the object itself.
+    def gid(author)
+      return if author.blank?
+      return author.to_gid if author.respond_to?(:to_gid)
+      author
+    end
+  end
+end

decidim-core/lib/decidim/core.rb

@@ -15,6 +15,7 @@ module Decidim
   autoload :ParticipatorySpaceManifest, "decidim/participatory_space_manifest"
   autoload :ResourceManifest, "decidim/resource_manifest"
   autoload :Resourceable, "decidim/resourceable"
+  autoload :Traceable, "decidim/traceable"
   autoload :Reportable, "decidim/reportable"
   autoload :Authorable, "decidim/authorable"
   autoload :Participable, "decidim/participable"
@@ -255,4 +256,9 @@ def self.menu(name, &block)
   def self.view_hooks
     @view_hooks ||= ViewHooks.new
   end
+
+  # Public: Stores an instance of Traceability
+  def self.traceability
+    @traceability ||= Traceability.new
+  end
 end

decidim-core/lib/decidim/traceable.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+require "active_support/concern"
+
+module Decidim
+  # A concern that adds traceabilty capability to the given model. Including this
+  # allows you the keep track of changes in the model attributes and changes authorship.
+  #
+  # Example:
+  #
+  #     class MyModel < ApplicationRecord
+  #       include Decidim::Traceable
+  #     end
+  module Traceable
+    extend ActiveSupport::Concern
+
+    included do
+      has_paper_trail
+    end
+  end
+end

decidim-core/spec/services/decidim/traceability_spec.rb

@@ -0,0 +1,66 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+
+describe Decidim::Traceability, versioning: true do
+  let!(:user) { create :user }
+  let(:klass) { Decidim::DummyResources::DummyResource }
+  let(:params) { attributes_for(:dummy_resource) }
+  subject { described_class.new }
+
+  describe "create" do
+    it "calls `create` to the class" do
+      expect(klass).to receive(:create).with(params)
+      subject.create(klass, user, params)
+    end
+
+    it "generates a new version for the resource" do
+      resource = subject.create(klass, user, params)
+      expect(resource.versions.count).to eq 1
+      expect(resource.versions.last.event).to eq "create"
+    end
+
+    it "sets the author of the version to the user" do
+      resource = subject.create(klass, user, params)
+      expect(resource.versions.last.whodunnit).to eq user.to_gid.to_s
+    end
+  end
+
+  describe "create!" do
+    it "calls `create!` to the class" do
+      expect(klass).to receive(:create!).with(params)
+      subject.create!(klass, user, params)
+    end
+
+    it "generates a new version for the resource" do
+      resource = subject.create!(klass, user, params)
+      expect(resource.versions.count).to eq 1
+      expect(resource.versions.last.event).to eq "create"
+    end
+
+    it "sets the author of the version to the user" do
+      resource = subject.create!(klass, user, params)
+      expect(resource.versions.last.whodunnit).to eq user.to_gid.to_s
+    end
+  end
+
+  describe "update!" do
+    let(:dummy_resource) { create :dummy_resource }
+
+    it "calls `update_attributes!` to the resource" do
+      expect(dummy_resource).to receive(:update_attributes!).with(params)
+      subject.update!(dummy_resource, user, params)
+    end
+
+    it "generates a new version for the resource" do
+      resource = subject.update!(dummy_resource, user, params)
+      expect(resource.versions.count).to eq 2
+      expect(resource.versions.last.event).to eq "update"
+    end
+
+    it "sets the author of the version to the user" do
+      resource = subject.update!(dummy_resource, user, params)
+      expect(resource.versions.last.whodunnit).to eq user.to_gid.to_s
+    end
+  end
+end

decidim-dev/lib/decidim/dev/test/rspec_support/feature.rb

@@ -41,6 +41,7 @@ class DummyResource < ApplicationRecord
       include HasScope
       include Decidim::Comments::Commentable
       include Followable
+      include Traceable
 
       feature_manifest_name "dummy"