Make collection caching explicit.

Having collection caching that wraps templates and automatically tries
to infer if they are cachable proved to be too much of a hassle.

We'd rather have it be something you explicitly turn on.

This removes much of the code and docs to explain the previous automatic
behavior.

This change also removes scoped cache keys and passing cache_options.

1 files changed, 7 insertions, 35 deletions

diff --git a/actionview/lib/action_view/helpers/cache_helper.rb b/actionview/lib/action_view/helpers/cache_helper.rb
index 401f398721..e842d8e31c 100644
--- a/actionview/lib/action_view/helpers/cache_helper.rb
+++ b/actionview/lib/action_view/helpers/cache_helper.rb
@@ -126,44 +126,16 @@ module ActionView
       #
       # Now all you have to do is change that timestamp when the helper method changes.
       #
-      # === Automatic Collection Caching
+      # === Collection Caching
       #
-      # When rendering collections such as:
+      # When rendering a collection of objects that each use the same partial, a `cached`
+      # option can be passed.
+      # For collections rendered such:
       #
-      #   <%= render @notifications %>
-      #   <%= render partial: 'notifications/notification', collection: @notifications %>
+      #   <%= render partial: 'notifications/notification', collection: @notifications, cached: true %>
       #
-      # If the notifications/_notification partial starts with a cache call as:
-      #
-      #   <% cache notification do %>
-      #     <%= notification.name %>
-      #   <% end %>
-      #
-      # The collection can then automatically use any cached renders for that
-      # template by reading them at once instead of one by one.
-      #
-      # See ActionView::Template::Handlers::ERB.resource_cache_call_pattern for
-      # more information on what cache calls make a template eligible for this
-      # collection caching.
-      #
-      # The automatic cache multi read can be turned off like so:
-      #
-      #   <%= render @notifications, cache: false %>
-      #
-      # === Explicit Collection Caching
-      #
-      # If the partial template doesn't start with a clean cache call as
-      # mentioned above, you can still benefit from collection caching by
-      # adding a special comment format anywhere in the template, like:
-      #
-      #   <%# Template Collection: notification %>
-      #   <% my_helper_that_calls_cache(some_arg, notification) do %>
-      #     <%= notification.name %>
-      #   <% end %>
-      #
-      # The pattern used to match these is <tt>/# Template Collection: (\S+)/</tt>,
-      # so it's important that you type it out just so.
-      # You can only declare one collection in a partial template file.
+      # The `cached: true` will make Action Views rendering issue a `read_multi` to
+      # the cache store instead of reading from it for every partial.
       def cache(name = {}, options = {}, &block)
         if controller.respond_to?(:perform_caching) && controller.perform_caching
           name_options = options.slice(:skip_digest, :virtual_path)