Added ability to set asset_path for engines

4 files changed, 39 insertions, 12 deletions

diff --git a/railties/lib/rails/application.rb b/railties/lib/rails/application.rb
index 300d4c6ab9..7c590b701e 100644
--- a/railties/lib/rails/application.rb
+++ b/railties/lib/rails/application.rb
@@ -124,16 +124,12 @@ module Rails
 
     alias :build_middleware_stack :app
 
-    def call(env)
-      env["action_dispatch.routes"] = routes
-      app.call(env.reverse_merge!(env_defaults))
-    end
-
-    def env_defaults
-      @env_defaults ||= {
+    def env_config
+      @env_config ||= super.merge({
         "action_dispatch.parameter_filter" => config.filter_parameters,
-        "action_dispatch.secret_token" => config.secret_token
-      }
+        "action_dispatch.secret_token" => config.secret_token,
+        "action_dispatch.asset_path" => nil
+      })
     end
 
     def initializers
diff --git a/railties/lib/rails/application/configuration.rb b/railties/lib/rails/application/configuration.rb
index 7e34a16487..29fa9d14eb 100644
--- a/railties/lib/rails/application/configuration.rb
+++ b/railties/lib/rails/application/configuration.rb
@@ -25,6 +25,18 @@ module Rails
         @middleware = app_middleware
       end
 
+      def asset_path=(value)
+        action_mailer.asset_path = value if respond_to?(:action_mailer) && action_mailer
+        action_controller.asset_path = value if respond_to?(:action_controller) && action_controller
+        super(value)
+      end
+
+      def asset_host=(value)
+        action_mailer.asset_host = value if action_mailer
+        action_controller.asset_host = value if action_controller
+        super(value)
+      end
+
       def encoding=(value)
         @encoding = value
         if "ruby".encoding_aware?
diff --git a/railties/lib/rails/engine.rb b/railties/lib/rails/engine.rb
index d4a654fd08..6b1e21a798 100644
--- a/railties/lib/rails/engine.rb
+++ b/railties/lib/rails/engine.rb
@@ -147,6 +147,19 @@ module Rails
   #
   # Now, Engine will get only requests that were not handled by application.
   #
+  # == Asset path
+  #
+  # When you use engine with its own public directory, you will probably want to copy or symlink it
+  # to application's public directory. To simplify generating paths for assets, you can set asset_path
+  # for an Engine:
+  #
+  # class MyEngine::Engine < Rails::Engine
+  #   config.asset_path = "/my_engine/%s"
+  # end
+  #
+  # With such config, asset paths will be automatically modified inside Engine:
+  # image_path("foo.jpg") #=> "/my_engine/images/foo.jpg"
+  #
   class Engine < Railtie
     autoload :Configurable,  "rails/engine/configurable"
     autoload :Configuration, "rails/engine/configuration"
@@ -219,8 +232,14 @@ module Rails
     end
 
     def call(env)
-      env["action_dispatch.routes"] = routes
-      app.call(env)
+      app.call(env.merge!(env_config))
+    end
+
+    def env_config
+      @env_config ||= {
+        'action_dispatch.routes' => routes,
+        'action_dispatch.asset_path' => config.asset_path
+      }
     end
 
     def routes
diff --git a/railties/lib/rails/engine/configuration.rb b/railties/lib/rails/engine/configuration.rb
index bf3ad1f26b..4588c27277 100644
--- a/railties/lib/rails/engine/configuration.rb
+++ b/railties/lib/rails/engine/configuration.rb
@@ -5,7 +5,7 @@ module Rails
     class Configuration < ::Rails::Railtie::Configuration
       attr_reader :root
       attr_writer :eager_load_paths, :autoload_once_paths, :autoload_paths
-      attr_accessor :middleware, :plugins
+      attr_accessor :middleware, :plugins, :asset_path
 
       def initialize(root=nil)
         super()