1 files changed, 35 insertions, 9 deletions

diff --git a/activerecord/lib/rails/generators/active_record/model/model_generator.rb b/activerecord/lib/rails/generators/active_record/model/model_generator.rb
index 395951ac9d..f191eff5bf 100644
--- a/activerecord/lib/rails/generators/active_record/model/model_generator.rb
+++ b/activerecord/lib/rails/generators/active_record/model/model_generator.rb
@@ -22,30 +22,56 @@ module ActiveRecord
 
       def create_model_file
         template 'model.rb', File.join('app/models', class_path, "#{file_name}.rb")
+        generate_application_record
       end
 
       def create_module_file
         return if regular_class_path.empty?
         template 'module.rb', File.join('app/models', "#{class_path.join('/')}.rb") if behavior == :invoke
-      end
-
-      def attributes_with_index
-        attributes.select { |a| !a.reference? && a.has_index? }
-      end
-
-      def accessible_attributes
-        attributes.reject(&:reference?)
+        generate_application_record
       end
 
       hook_for :test_framework
 
       protected
 
+        def attributes_with_index
+          attributes.select { |a| !a.reference? && a.has_index? }
+        end
+
+        # FIXME: Change this file to a symlink once RubyGems 2.5.0 is required.
+        def generate_application_record
+          if self.behavior == :invoke && !application_record_exist?
+            template 'application_record.rb', application_record_file_name
+          end
+        end
+
         # Used by the migration template to determine the parent name of the model
         def parent_class_name
-          options[:parent] || "ActiveRecord::Base"
+          options[:parent] || determine_default_parent_class
+        end
+
+        def application_record_exist?
+          file_exist = nil
+          in_root { file_exist = File.exist?(application_record_file_name) }
+          file_exist
         end
 
+        def application_record_file_name
+          @application_record_file_name ||= if mountable_engine?
+            "app/models/#{namespaced_path}/application_record.rb"
+          else
+            'app/models/application_record.rb'
+          end
+        end
+
+        def determine_default_parent_class
+          if application_record_exist?
+            "ApplicationRecord"
+          else
+            "ActiveRecord::Base"
+          end
+        end
     end
   end
 end