Added instruction in Rails 3.1. install generator

lib/generators/jquery/install/install_generator.rb

@@ -1,39 +1,56 @@
 require 'rails'
 
-module Jquery
-  module Generators
-    class InstallGenerator < ::Rails::Generators::Base
+if ::Rails.version < "3.1"
+  module Jquery
+    module Generators
+      class InstallGenerator < ::Rails::Generators::Base
 
-      desc "This generator installs jQuery #{Jquery::Rails::JQUERY_VERSION}, jQuery-ujs, and (optionally) jQuery UI #{Jquery::Rails::JQUERY_UI_VERSION}"
-      class_option :ui, :type => :boolean, :default => false, :desc => "Include jQueryUI"
-      source_root File.expand_path('../../../../../vendor/assets/javascripts', __FILE__)
+        desc "This generator installs jQuery #{Jquery::Rails::JQUERY_VERSION}, jQuery-ujs, and (optionally) jQuery UI #{Jquery::Rails::JQUERY_UI_VERSION}"
+        class_option :ui, :type => :boolean, :default => false, :desc => "Include jQueryUI"
+        source_root File.expand_path('../../../../../vendor/assets/javascripts', __FILE__)
 
-      def remove_prototype
-        Rails::PROTOTYPE_JS.each do |name|
-          remove_file "public/javascripts/#{name}.js"
+        def remove_prototype
+          Rails::PROTOTYPE_JS.each do |name|
+            remove_file "public/javascripts/#{name}.js"
+          end
         end
-      end
 
-      def copy_jquery
-        say_status("copying", "jQuery (#{Jquery::Rails::JQUERY_VERSION})", :green)
-        copy_file "jquery.js", "public/javascripts/jquery.js"
-        copy_file "jquery.min.js", "public/javascripts/jquery.min.js"
-      end
+        def copy_jquery
+          say_status("copying", "jQuery (#{Jquery::Rails::JQUERY_VERSION})", :green)
+          copy_file "jquery.js", "public/javascripts/jquery.js"
+          copy_file "jquery.min.js", "public/javascripts/jquery.min.js"
+        end
 
-      def copy_jquery_ui
-        if options.ui?
-          say_status("copying", "jQuery UI (#{Jquery::Rails::JQUERY_UI_VERSION})", :green)
-          copy_file "jquery-ui.js", "public/javascripts/jquery-ui.js"
-          copy_file "jquery-ui.min.js", "public/javascripts/jquery-ui.min.js"
+        def copy_jquery_ui
+          if options.ui?
+            say_status("copying", "jQuery UI (#{Jquery::Rails::JQUERY_UI_VERSION})", :green)
+            copy_file "jquery-ui.js", "public/javascripts/jquery-ui.js"
+            copy_file "jquery-ui.min.js", "public/javascripts/jquery-ui.min.js"
+          end
+        end
+
+        def copy_ujs_driver
+          say_status("copying", "jQuery UJS adapter (#{Jquery::Rails::JQUERY_UJS_VERSION[0..5]})", :green)
+          remove_file "public/javascripts/rails.js"
+          copy_file "jquery_ujs.js", "public/javascripts/jquery_ujs.js"
         end
-      end
 
-      def copy_ujs_driver
-        say_status("copying", "jQuery UJS adapter (#{Jquery::Rails::JQUERY_UJS_VERSION[0..5]})", :green)
-        remove_file "public/javascripts/rails.js"
-        copy_file "jquery_ujs.js", "public/javascripts/jquery_ujs.js"
       end
+    end
+  end
+else
+  module Jquery
+    module Generators
+      class InstallGenerator < ::Rails::Generators::Base
+        desc "Just show instructions so people will know what to do when mistakenly using generator for Rails 3.1 apps"
 
+        def do_nothing
+          say_status("deprecated", "You are using Rails 3.1, so this generator is no longer needed. The necessary files are already in your asset pipeline.")
+          say_status("", "Just add `//= require jquery` and `//= require jquery_ujs` to your app/assets/javascripts/application.js")
+          say_status("", "If you upgraded your app from Rails 3.0 and still have jquery.js, rails.js, or jquery_ujs.js in your javascripts, be sure to remove them.")
+          # ok, nothing
+        end
+      end
     end
   end
-end if ::Rails.version < "3.1"
+end