diff --git a/app/models/application_record.rb b/app/models/application_record.rb
index 71fbba5b328..29696ab276f 100644
--- a/app/models/application_record.rb
+++ b/app/models/application_record.rb
@@ -2,4 +2,8 @@
 
 class ApplicationRecord < ActiveRecord::Base
   self.abstract_class = true
+
+  def self.id_in(ids)
+    where(id: ids)
+  end
 end
diff --git a/app/models/namespace.rb b/app/models/namespace.rb
index a0bebc5e9a2..f7592532c5b 100644
--- a/app/models/namespace.rb
+++ b/app/models/namespace.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-class Namespace < ActiveRecord::Base
+class Namespace < ApplicationRecord
   include CacheMarkdownField
   include Sortable
   include Gitlab::VisibilityLevel
diff --git a/app/models/user.rb b/app/models/user.rb
index 4ef5bdc2d12..f8ac230852f 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -2,7 +2,7 @@
 
 require 'carrierwave/orm/activerecord'
 
-class User < ActiveRecord::Base
+class User < ApplicationRecord
   extend Gitlab::ConfigHelper
 
   include Gitlab::ConfigHelper
diff --git a/spec/models/application_record_spec.rb b/spec/models/application_record_spec.rb
new file mode 100644
index 00000000000..68aed387bfc
--- /dev/null
+++ b/spec/models/application_record_spec.rb
@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe ApplicationRecord do
+  describe '#id_in' do
+    let(:records) { create_list(:user, 3) }
+
+    it 'returns records of the ids' do
+      expect(User.id_in(records.last(2).map(&:id))).to eq(records.last(2))
+    end
+  end
+end