Add query method for id query

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

app/models/namespace.rb

 # frozen_string_literal: true
 
-class Namespace < ActiveRecord::Base
+class Namespace < ApplicationRecord
   include CacheMarkdownField
   include Sortable
   include Gitlab::VisibilityLevel

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

spec/models/application_record_spec.rb

+# 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