1 files changed, 25 insertions, 6 deletions
diff --git a/activerecord/lib/active_record/railtie.rb b/activerecord/lib/active_record/railtie.rb
index 47133e77e8..165d0750dd 100644
--- a/activerecord/lib/active_record/railtie.rb
+++ b/activerecord/lib/active_record/railtie.rb
@@ -22,6 +22,13 @@ module ActiveRecord
     config.app_middleware.insert_after "::ActionDispatch::Callbacks",
       "ActiveRecord::ConnectionAdapters::ConnectionManagement"
 
+    config.action_dispatch.rescue_responses.merge!(
+      'ActiveRecord::RecordNotFound'   => :not_found,
+      'ActiveRecord::StaleObjectError' => :conflict,
+      'ActiveRecord::RecordInvalid'    => :unprocessable_entity,
+      'ActiveRecord::RecordNotSaved'   => :unprocessable_entity
+    )
+
     rake_tasks do
       load "active_record/railties/databases.rake"
     end
@@ -78,18 +85,30 @@ module ActiveRecord
       end
     end
 
-    initializer "active_record.set_dispatch_hooks", :before => :set_clear_dependencies_hook do |app|
-      ActiveSupport.on_load(:active_record) do
-        ActionDispatch::Reloader.to_cleanup do
-          ActiveRecord::Base.clear_reloadable_connections!
-          ActiveRecord::Base.clear_cache!
+    initializer "active_record.set_reloader_hooks" do |app|
+      hook = lambda do
+        ActiveRecord::Base.clear_reloadable_connections!
+        ActiveRecord::Base.clear_cache!
+      end
+
+      if app.config.reload_classes_only_on_change
+        ActiveSupport.on_load(:active_record) do
+          ActionDispatch::Reloader.to_prepare(&hook)
+        end
+      else
+        ActiveSupport.on_load(:active_record) do
+          ActionDispatch::Reloader.to_cleanup(&hook)
         end
       end
     end
 
+    initializer "active_record.add_watchable_files" do |app|
+      config.watchable_files.concat ["#{app.root}/db/schema.rb", "#{app.root}/db/structure.sql"]
+    end
+
     config.after_initialize do
       ActiveSupport.on_load(:active_record) do
-        instantiate_observers
+        ActiveRecord::Base.instantiate_observers
 
         ActionDispatch::Reloader.to_prepare do
           ActiveRecord::Base.instantiate_observers