Allow fragment cache to accept :if and :unless options

[Stephen Ausman + Fabrizio Regini]

actionpack/CHANGELOG.md

@@ -1,4 +1,10 @@
 ## Rails 4.0.0 (unreleased) ##
+*   Add :if / :unless conditions to fragment cache:
+
+        <%= cache @model, if: some_condition(@model) do %>
+
+    *Stephen Ausman + Fabrizio Regini*
+
 *   Add filter capability to ActionController logs for redirect locations:
 
         config.filter_redirect << 'http://please.hide.it/'

actionpack/lib/action_view/helpers/cache_helper.rb

@@ -110,8 +110,15 @@ module CacheHelper
       #   <%= some_helper_method(person) %>
       #
       # Now all you'll have to do is change that timestamp when the helper method changes.
+      #
+      # ==== Conditional caching
+      #
+      # You can pass :if and :unless options, to conditionally perform or skip the cache.
+      #
+      #   <%= cache @model, if: some_condition(@model) do %>
+      #
       def cache(name = {}, options = nil, &block)
-        if controller.perform_caching
+        if controller.perform_caching && conditions_match?(options)
           safe_concat(fragment_for(cache_fragment_name(name, options), options, &block))
         else
           yield
@@ -136,6 +143,11 @@ def cache_fragment_name(name = {}, options = nil)
       end
 
     private
+
+      def conditions_match?(options)
+        !(options && (!options.fetch(:if, true) || options.fetch(:unless, false)))
+      end
+
       def fragment_name_with_digest(name) #:nodoc:
         if @virtual_path
           [

actionpack/test/controller/log_subscriber_test.rb

@@ -46,6 +46,22 @@ def with_fragment_cache_and_percent_in_key
       render :inline => "<%= cache('foo%bar'){ 'Contains % sign in key' } %>"
     end
 
+    def with_fragment_cache_and_if_true_condition
+      render :inline => "<%= cache('foo', :if => true) { 'bar' } %>"
+    end
+
+    def with_fragment_cache_and_if_false_condition
+      render :inline => "<%= cache('foo', :if => false) { 'bar' } %>"
+    end
+
+    def with_fragment_cache_and_unless_false_condition
+      render :inline => "<%= cache('foo', :unless => false) { 'bar' } %>"
+    end
+
+    def with_fragment_cache_and_unless_true_condition
+      render :inline => "<%= cache('foo', :unless => true) { 'bar' } %>"
+    end
+
     def with_exception
       raise Exception
     end
@@ -203,6 +219,54 @@ def test_with_fragment_cache
     @controller.config.perform_caching = true
   end
 
+  def test_with_fragment_cache_and_if_true
+    @controller.config.perform_caching = true
+    get :with_fragment_cache_and_if_true_condition
+    wait
+
+    assert_equal 4, logs.size
+    assert_match(/Read fragment views\/foo/, logs[1])
+    assert_match(/Write fragment views\/foo/, logs[2])
+  ensure
+    @controller.config.perform_caching = true
+  end
+
+  def test_with_fragment_cache_and_if_false
+    @controller.config.perform_caching = true
+    get :with_fragment_cache_and_if_false_condition
+    wait
+
+    assert_equal 2, logs.size
+    assert_no_match(/Read fragment views\/foo/, logs[1])
+    assert_no_match(/Write fragment views\/foo/, logs[2])
+  ensure
+    @controller.config.perform_caching = true
+  end
+
+  def test_with_fragment_cache_and_unless_true
+    @controller.config.perform_caching = true
+    get :with_fragment_cache_and_unless_true_condition
+    wait
+
+    assert_equal 2, logs.size
+    assert_no_match(/Read fragment views\/foo/, logs[1])
+    assert_no_match(/Write fragment views\/foo/, logs[2])
+  ensure
+    @controller.config.perform_caching = true
+  end
+
+  def test_with_fragment_cache_and_unless_false
+    @controller.config.perform_caching = true
+    get :with_fragment_cache_and_unless_false_condition
+    wait
+
+    assert_equal 4, logs.size
+    assert_match(/Read fragment views\/foo/, logs[1])
+    assert_match(/Write fragment views\/foo/, logs[2])
+  ensure
+    @controller.config.perform_caching = true
+  end
+
   def test_with_fragment_cache_and_percent_in_key
     @controller.config.perform_caching = true
     get :with_fragment_cache_and_percent_in_key