Merge multi_fetch_fragments.

Makes caching a collection of template partials faster using `read_multi`
on the Rails cache store.

Some caching implementations have optimized `read_multi` so we don't have
to check in the cache store for every template.

1 files changed, 8 insertions, 0 deletions

diff --git a/actionview/lib/action_view/helpers/cache_helper.rb b/actionview/lib/action_view/helpers/cache_helper.rb
index 4db8930a26..56b1c5049c 100644
--- a/actionview/lib/action_view/helpers/cache_helper.rb
+++ b/actionview/lib/action_view/helpers/cache_helper.rb
@@ -161,6 +161,14 @@ module ActionView
         end
       end
 
+      # Given a key (as described in ActionController::Caching::Fragments.expire_fragment),
+      # returns a key suitable for use in reading, writing, or expiring a
+      # cached fragment. All keys are prefixed with <tt>views/</tt> and uses
+      # ActiveSupport::Cache.expand_cache_key for the expansion.
+      def fragment_cache_key(key)
+        ActiveSupport::Cache.expand_cache_key(key.is_a?(Hash) ? url_for(key).split("://").last : key, :views)
+      end
+
     private
 
       def fragment_name_with_digest(name) #:nodoc: