Improved error message for DoubleRenderError

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@1779 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

actionpack/CHANGELOG

 *SVN*
 
+* Improved error message for DoubleRenderError
+
 * Fixed routing to allow for testing of *path components #1650 [Nicholas Seckar]
 
 * Added :handle as an option to sortable_element to restrict the drag handle to a given class #1642 [thejohnny]

actionpack/lib/action_controller/base.rb

@@ -26,6 +26,11 @@ class UnknownAction < ActionControllerError #:nodoc:
   class MissingFile < ActionControllerError #:nodoc:
   end
   class DoubleRenderError < ActionControllerError #:nodoc:
+    DEFAULT_MESSAGE = "Render and/or redirect were called multiple times in this action. Please note that you may only call render OR redirect, and only once per action. Also note that neither redirect nor render terminate execution of the action, so if you want to exit an action after redirecting, you need to do something like \"redirect_to(...) and return\". Finally, note that to cause a before filter to halt execution of the rest of the filter chain, the filter must return false, explicitly, so \"render(...) and return false\"." 
+
+    def initialize(message=nil)
+      super(message || DEFAULT_MESSAGE)
+    end
   end
 
   # Action Controllers are made up of one or more actions that performs its purpose and then either renders a template or
@@ -560,7 +565,7 @@ def controller_name
       #   render :nothing => true, :status => 401
       def render(options = {}, deprecated_status = nil) #:doc:
         # puts "Rendering: #{options.inspect}"
-        raise DoubleRenderError, "Can only render or redirect once per action" if performed?
+        raise DoubleRenderError if performed?
 
         # Backwards compatibility
         return render({ :template => options || default_template_name, :status => deprecated_status }) if !options.is_a?(Hash)
@@ -684,7 +689,7 @@ def default_url_options(options) #:doc:
       def redirect_to(options = {}, *parameters_for_method_reference) #:doc:
         case options
           when %r{^\w+://.*}
-            raise DoubleRenderError, "Can only render or redirect once per action" if performed?
+            raise DoubleRenderError if performed?
             logger.info("Redirected to #{options}") unless logger.nil?
             response.redirect(options)
             response.redirected_to = options

actionpack/test/controller/new_render_test.rb

@@ -99,6 +99,21 @@ def render_with_explicit_template
     render "test/hello_world"
   end
 
+  def double_render
+    render :text => "hello"
+    render :text => "world"
+  end
+
+  def double_redirect
+    redirect_to :action => "double_render"
+    redirect_to :action => "double_render"
+  end
+
+  def render_and_redirect
+    render :text => "hello"
+    redirect_to :action => "double_render"
+  end
+
   def rescue_action(e) raise end
     
   private
@@ -260,4 +275,16 @@ def test_render_with_explicit_template
     get :render_with_explicit_template
     assert_response :success
   end
+
+  def test_double_render
+    assert_raises(ActionController::DoubleRenderError) { get :double_render }
+  end
+
+  def test_double_redirect
+    assert_raises(ActionController::DoubleRenderError) { get :double_redirect }
+  end
+
+  def test_render_and_redirect
+    assert_raises(ActionController::DoubleRenderError) { get :render_and_redirect }
+  end
 end