Added that rendering will automatically insert the etag header on 200 OK responses. The etag is calculated using MD5 of the response body. If a request comes in that has a matching etag, the response will be changed to a 304 Not Modified and the response body will be set to an empty string. [DHH]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@6158 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

actionpack/CHANGELOG

@@ -1,5 +1,7 @@
 *SVN*
 
+* Added that rendering will automatically insert the etag header on 200 OK responses. The etag is calculated using MD5 of the response body. If a request comes in that has a matching etag, the response will be changed to a 304 Not Modified and the response body will be set to an empty string. [DHH]
+
 * Added X-Runtime to all responses with the request run time [DHH]
 
 * Add Mime::Type convenience methods to check the current mime type. [Rick]

actionpack/lib/action_controller/base.rb

@@ -7,6 +7,7 @@ require 'action_controller/url_rewriter'
 require 'action_controller/status_codes'
 require 'drb'
 require 'set'
+require 'md5'
 
 module ActionController #:nodoc:
   class ActionControllerError < StandardError #:nodoc:
@@ -648,6 +649,12 @@ module ActionController #:nodoc:
       # <tt>render_partial(partial_path = default_template_name, object = nil, local_assigns = {})</tt> and
       # <tt>render_partial_collection(partial_name, collection, partial_spacer_template = nil, local_assigns = {})</tt>.
       #
+      # == Automatic etagging
+      #
+      # Rendering will automatically insert the etag header on 200 OK responses. The etag is calculated using MD5 of the
+      # response body. If a request comes in that has a matching etag, the response will be changed to a 304 Not Modified
+      # and the response body will be set to an empty string.
+      #
       # === Rendering a template
       #
       # Template rendering works just like action rendering except that it takes a path relative to the template root.
@@ -870,6 +877,17 @@ module ActionController #:nodoc:
         else
           response.body = text
         end
+
+        if response.headers['Status'] == "200 OK" && response.body.size > 0
+          response.headers['Etag'] = "\"#{MD5.new(text).to_s}\""
+          
+          if request.headers['HTTP_IF_NONE_MATCH'] == response.headers['Etag']
+            response.headers['Status'] = "304 Not Modified"
+            response.body = ''
+          end
+        end
+        
+        response.body
       end
 
       def render_javascript(javascript, status = nil, append_response = true) #:nodoc:

actionpack/lib/action_controller/request.rb

@@ -51,6 +51,10 @@ module ActionController
       @env['REQUEST_METHOD'].downcase.to_sym == :head
     end
 
+    def headers
+      @env
+    end
+
     # Determine whether the body of a HTTP call is URL-encoded (default)
     # or matches one of the registered param_parsers. 
     #

actionpack/test/controller/render_test.rb

@@ -69,6 +69,10 @@ class TestController < ActionController::Base
     render "test/hello"
   end
 
+  def heading
+    head :ok
+  end
+
   def greeting
     # let's just rely on the template
   end
@@ -286,8 +290,50 @@ class RenderTest < Test::Unit::TestCase
     assert_equal "Goodbye, Local David", @response.body
   end
 
+  def test_render_200_should_set_etag
+    get :render_hello_world_from_variable
+    assert_equal etag_for("hello david"), @response.headers['Etag']
+  end
+
+  def test_render_against_etag_request_should_304_when_match
+    @request.headers["HTTP_IF_NONE_MATCH"] = etag_for("hello david")
+    get :render_hello_world_from_variable
+    assert_equal "304 Not Modified", @response.headers['Status']
+    assert @response.body.empty?
+  end
+
+  def test_render_against_etag_request_should_200_when_no_match
+    @request.headers["HTTP_IF_NONE_MATCH"] = etag_for("hello somewhere else")
+    get :render_hello_world_from_variable
+    assert_equal "200 OK", @response.headers['Status']
+    assert !@response.body.empty?
+  end
+
+  def test_render_with_etag
+    get :render_hello_world_from_variable
+    expected_etag = "\"#{MD5.new("hello david").to_s}\""
+    assert_equal expected_etag, @response.headers['Etag']
+    
+    @request.headers["HTTP_IF_NONE_MATCH"] = expected_etag
+    get :render_hello_world_from_variable
+    assert_equal "304 Not Modified", @response.headers['Status']
+    
+    @request.headers["HTTP_IF_NONE_MATCH"] = "\"diftag\""
+    get :render_hello_world_from_variable
+    assert_equal "200 OK", @response.headers['Status']
+  end
+
+  def render_with_404_shouldnt_have_etag
+    get :render_custom_code
+    assert_nil @response.headers['Etag']
+  end
+
   protected
     def assert_deprecated_render(&block)
       assert_deprecated(/render/, &block)
     end
+    
+    def etag_for(text)
+      "\"#{MD5.new(text).to_s}\""
+    end
 end