use has_many relationship with events

app/models/concerns/eventable.rb

-module Eventable
-  extend ActiveSupport::Concern
-
-  def events
-    Event.where(target_id: id, target_type: self.class.to_s)
-  end
-
-  def events=(events)
-    events.each do |event|
-      event.target_id = id
-      event.data.deep_symbolize_keys! if event.data
-      event.save!
-    end
-  end
-end

app/models/issue.rb

@@ -6,7 +6,6 @@ class Issue < ActiveRecord::Base
   include Referable
   include Sortable
   include Taskable
-  include Eventable
 
   DueDateStruct = Struct.new(:title, :name).freeze
   NoDueDate     = DueDateStruct.new('No Due Date', '0').freeze
@@ -20,6 +19,8 @@ class Issue < ActiveRecord::Base
   belongs_to :project
   belongs_to :moved_to, class_name: 'Issue'
 
+  has_many :events, as: :target, dependent: :destroy
+
   validates :project, presence: true
 
   scope :cared, ->(user) { where(assignee_id: user) }

app/models/merge_request.rb

@@ -5,7 +5,6 @@ class MergeRequest < ActiveRecord::Base
   include Sortable
   include Taskable
   include Importable
-  include Eventable
 
   belongs_to :target_project, foreign_key: :target_project_id, class_name: "Project"
   belongs_to :source_project, foreign_key: :source_project_id, class_name: "Project"
@@ -13,6 +12,8 @@ class MergeRequest < ActiveRecord::Base
 
   has_one :merge_request_diff, dependent: :destroy
 
+  has_many :events, as: :target, dependent: :destroy
+
   serialize :merge_params, Hash
 
   after_create :create_merge_request_diff, unless: :importing

app/models/milestone.rb

@@ -11,13 +11,13 @@ class Milestone < ActiveRecord::Base
   include Referable
   include StripAttribute
   include Milestoneish
-  include Eventable
 
   belongs_to :project
   has_many :issues
   has_many :labels, -> { distinct.reorder('labels.title') },  through: :issues
   has_many :merge_requests
   has_many :participants, -> { distinct.reorder('users.name') }, through: :issues, source: :assignee
+  has_many :events, as: :target, dependent: :destroy
 
   scope :active, -> { with_state(:active) }
   scope :closed, -> { with_state(:closed) }

app/models/note.rb

@@ -5,7 +5,6 @@ class Note < ActiveRecord::Base
   include Mentionable
   include Awardable
   include Importable
-  include Eventable
 
   # Attribute containing rendered and redacted Markdown as generated by
   # Banzai::ObjectRenderer.
@@ -22,6 +21,7 @@ class Note < ActiveRecord::Base
   belongs_to :updated_by, class_name: "User"
 
   has_many :todos, dependent: :destroy
+  has_many :events, as: :target, dependent: :destroy
 
   delegate :gfm_reference, :local_reference, to: :noteable
   delegate :name, to: :project, prefix: true

lib/gitlab/import_export/relation_factory.rb

@@ -33,6 +33,7 @@ module Gitlab
         update_user_references
         update_project_references
         reset_ci_tokens if @relation_name == 'Ci::Trigger'
+        @relation_hash['data'].deep_symbolize_keys! if @relation_name == :events && @relation_hash['data']
 
         generate_imported_object
       end

spec/lib/gitlab/import_export/project_tree_restorer_spec.rb

@@ -24,6 +24,12 @@ describe Gitlab::ImportExport::ProjectTreeRestorer, services: true do
 
         expect(Ci::Pipeline.first.notes).not_to be_empty
       end
+
+      it 'restores the correct event' do
+        restored_project_json
+
+        expect(Event.where.not(data: nil).first.data[:ref]).not_to be_empty
+      end
     end
   end
 end