Merge branch 'fix/import-event-error' into 'master'

Fix problems with events under notes importing GitLab projects

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/19588

See merge request !5154
(cherry picked from commit 734e44ee79590be6d9f01ca3e815304221a5c88d)

4 files changed, 39 insertions, 2 deletions

diff --git a/CHANGELOG b/CHANGELOG
index 85851f59518..4990d408bda 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,6 +1,7 @@
 Please view this file on the master branch, on stable branches it's out of date.
 
 v 8.9.6
+  - Fix importing of events under notes for GitLab projects. !5154
   - Fix log statements in import/export. !5129
   - Fix commit avatar alignment in compare view. !5128
   - Fix broken migration in MySQL. !5005
diff --git a/lib/gitlab/import_export/project_tree_restorer.rb b/lib/gitlab/import_export/project_tree_restorer.rb
index dd71b92c522..e2413b082b2 100644
--- a/lib/gitlab/import_export/project_tree_restorer.rb
+++ b/lib/gitlab/import_export/project_tree_restorer.rb
@@ -70,10 +70,19 @@ module Gitlab
       # Example:
       # +relation_key+ issues, loops through the list of *issues* and for each individual
       # issue, finds any subrelations such as notes, creates them and assign them back to the hash
+      #
+      # Recursively calls this method if the sub-relation is a hash containing more sub-relations
       def create_sub_relations(relation, tree_hash)
         relation_key = relation.keys.first.to_s
+        return if tree_hash[relation_key].blank?
+
         tree_hash[relation_key].each do |relation_item|
           relation.values.flatten.each do |sub_relation|
+            # We just use author to get the user ID, do not attempt to create an instance.
+            next if sub_relation == :author
+
+            create_sub_relations(sub_relation, relation_item) if sub_relation.is_a?(Hash)
+
             relation_hash, sub_relation = assign_relation_hash(relation_item, sub_relation)
             relation_item[sub_relation.to_s] = create_relation(sub_relation, relation_hash) unless relation_hash.blank?
           end
diff --git a/spec/lib/gitlab/import_export/project.json b/spec/lib/gitlab/import_export/project.json
index 0b30e8c9b04..7286b0c39c0 100644
--- a/spec/lib/gitlab/import_export/project.json
+++ b/spec/lib/gitlab/import_export/project.json
@@ -4208,7 +4208,18 @@
             "name": "User 4"
           },
           "events": [
-
+            {
+              "id": 529,
+              "target_type": "Note",
+              "target_id": 2521,
+              "title": "test levels",
+              "data": null,
+              "project_id": 4,
+              "created_at": "2016-07-07T14:35:12.128Z",
+              "updated_at": "2016-07-07T14:35:12.128Z",
+              "action": 6,
+              "author_id": 1
+            }
           ]
         },
         {
diff --git a/spec/lib/gitlab/import_export/project_tree_restorer_spec.rb b/spec/lib/gitlab/import_export/project_tree_restorer_spec.rb
index e401ca99077..d2d0a05ad5c 100644
--- a/spec/lib/gitlab/import_export/project_tree_restorer_spec.rb
+++ b/spec/lib/gitlab/import_export/project_tree_restorer_spec.rb
@@ -25,11 +25,27 @@ describe Gitlab::ImportExport::ProjectTreeRestorer, services: true do
         expect(Ci::Pipeline.first.notes).not_to be_empty
       end
 
-      it 'restores the correct event' do
+      it 'restores the correct event with symbolised data' do
         restored_project_json
 
         expect(Event.where.not(data: nil).first.data[:ref]).not_to be_empty
       end
+
+      context 'event at forth level of the tree' do
+        let(:event) { Event.where(title: 'test levels').first }
+
+        before do
+          restored_project_json
+        end
+
+        it 'restores the event' do
+          expect(event).not_to be_nil
+        end
+
+        it 'event belongs to note, belongs to merge request, belongs to a project' do
+          expect(event.note.noteable.project).not_to be_nil
+        end
+      end
     end
   end
 end