From dc15b1c5609bd3a7122dafe30cce3d98ba31614f Mon Sep 17 00:00:00 2001
From: Ches Martin <ches@whiskeyandgrits.net>
Date: Tue, 29 Oct 2013 22:16:00 +0800
Subject: [PATCH] Instantiate observers via Railtie, and run load hooks

I spent some time figuring out how to cleanly use the
ActiveResource observer support in a Rails app, finding surprisingly
little documentation beyond ActiveModel::Observer itself, arriving at
the need for this essential boilerplate in an initializer:

    ActiveResource::Base.observers = # ...
    ActiveResource::Base.instantiate_observers

This change packages it up as neatly as ActiveRecord observers in Rails:

    # In config/application.rb
    config.active_resource.observers = [:post_observer, :comment_observer]

The Railtie will instantiate observers automatically, and reload them
for each request in development just like rails-observers does for
ActiveRecord.
---
 lib/active_resource.rb         |  3 +++
 lib/active_resource/base.rb    |  3 +++
 lib/active_resource/railtie.rb | 13 ++++++++++++-
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/lib/active_resource.rb b/lib/active_resource.rb
index b8c77a56e5..ef3490e009 100644
--- a/lib/active_resource.rb
+++ b/lib/active_resource.rb
@@ -41,3 +41,6 @@ module ActiveResource
   autoload :Validations
   autoload :Collection
 end
+
+require 'active_resource/railtie' if defined? Rails
+
diff --git a/lib/active_resource/base.rb b/lib/active_resource/base.rb
index f9a66bd7f9..dcac3ae8f2 100644
--- a/lib/active_resource/base.rb
+++ b/lib/active_resource/base.rb
@@ -1560,4 +1560,7 @@ class Base
     include ActiveModel::Serializers::Xml
     include ActiveResource::Reflection
   end
+
+  ActiveSupport.run_load_hooks(:active_resource, Base)
 end
+
diff --git a/lib/active_resource/railtie.rb b/lib/active_resource/railtie.rb
index 60f6f88311..6b0a433e97 100644
--- a/lib/active_resource/railtie.rb
+++ b/lib/active_resource/railtie.rb
@@ -10,5 +10,16 @@ class Railtie < Rails::Railtie
         ActiveResource::Base.send "#{k}=", v
       end
     end
+
+    config.after_initialize do |app|
+      ActiveSupport.on_load(:active_resource) do
+        ActiveResource::Base.instantiate_observers
+
+        ActionDispatch::Reloader.to_prepare do
+          ActiveResource::Base.instantiate_observers
+        end
+      end
+    end
   end
-end
\ No newline at end of file
+end
+