Pick only those groups that the viewing user has access to,

in a project members' list. Add tests for possible scenarios

Re-factor and remove N + 1 queries

Remove author from changelog

Don't use memoisation when not needed

Include users part of parents of project's group

Re-factor tests

Create and add users according to roles

Re-use group created earlier

Add incomplete test for ancestoral groups

Rename method to clarify category of groups

Skip pending test, remove comments not needed

Remove extra line

Include ancestors from invited groups as well

Add specs for participants service

Add more specs

Add more specs

use  instead of

Use public group owner instead of project maintainer to test owner acess

Remove tests that have now been moved into participants_service_spec

Use :context instead of :all

Create nested group instead of creating an ancestor separately

Add comment explaining doubt on the failing spec

Imrpove test setup

Optimize sql queries

Refactor specs file

Add rubocop disablement

Add special case for project owners

Add small refactor

Add explanation to the docs

Fix wording

Refactor group check

Add small changes in specs

Add cr remarks

Add cr remarks

Add specs

Add small refactor

Add code review remarks

Refactor for better database usage

Fix failing spec

Remove rubocop offences

Add cr remarks

2 files changed, 56 insertions, 2 deletions

diff --git a/app/models/member.rb b/app/models/member.rb
index e2d26773d45..2654453cf3f 100644
--- a/app/models/member.rb
+++ b/app/models/member.rb
@@ -8,6 +8,7 @@ class Member < ApplicationRecord
   include Gitlab::Access
   include Presentable
   include Gitlab::Utils::StrongMemoize
+  include FromUnion
 
   attr_accessor :raw_invite_token
 
diff --git a/app/services/projects/participants_service.rb b/app/services/projects/participants_service.rb
index 7080f388e53..1cd81fe37c7 100644
--- a/app/services/projects/participants_service.rb
+++ b/app/services/projects/participants_service.rb
@@ -7,16 +7,69 @@ module Projects
     def execute(noteable)
       @noteable = noteable
 
-      participants = noteable_owner + participants_in_noteable + all_members + groups + project_members
+      participants =
+        noteable_owner +
+        participants_in_noteable +
+        all_members +
+        groups +
+        project_members
+
       participants.uniq
     end
 
     def project_members
-      @project_members ||= sorted(project.team.members)
+      @project_members ||= sorted(get_project_members)
+    end
+
+    def get_project_members
+      members = Member.from_union([project_members_through_ancestral_groups,
+                                   project_members_through_invited_groups,
+                                   individual_project_members])
+
+      User.id_in(members.select(:user_id))
     end
 
     def all_members
       [{ username: "all", name: "All Project and Group Members", count: project_members.count }]
     end
+
+    private
+
+    def project_members_through_invited_groups
+      groups_with_ancestors_ids = Gitlab::ObjectHierarchy
+        .new(visible_groups)
+        .base_and_ancestors
+        .pluck_primary_key
+
+      GroupMember
+        .active_without_invites_and_requests
+        .with_source_id(groups_with_ancestors_ids)
+    end
+
+    def visible_groups
+      visible_groups = project.invited_groups
+
+      unless project_owner?
+        visible_groups = visible_groups.public_or_visible_to_user(current_user)
+      end
+
+      visible_groups
+    end
+
+    def project_members_through_ancestral_groups
+      project.group.present? ? project.group.members_with_parents : Member.none
+    end
+
+    def individual_project_members
+      project.project_members
+    end
+
+    def project_owner?
+      if project.group.present?
+        project.group.owners.include?(current_user)
+      else
+        project.namespace.owner == current_user
+      end
+    end
   end
 end