#90 Fragment Caching (revised)

A related blog post by 37Signals on this technique: http://37signals.com/svn/posts/3112-how-basecamp-next-got-to-be-so-damn-fast-without-using-much-client-side-ui

What's a good way to auto-expire the "recent_articles" fragment you have there? Would something like this work?

<% cache ["recent_articles"] + @recent_articles do %>
<div id="recent_articles">
  <h3>Recent Articles</h3>
  <ul>
  <% @recent_articles.each do |article| %>
    <% cache ["recent", article] do %>
      <li><%= link_to article.name, article %></li>
    <% end %>
  <% end %>
  </ul>
</div>
<% end %>

Does it make sense to nest cache resources this way? Is it Rails so slow to render a template that you should waste more cache memory?

check out this http://37signals.com/svn/posts/3113-how-key-based-cache-expiration-works Sofia Cardita of 37 signals does a great job explaining caching

Hi i have a strange issue with fragment caching with rails 3.2 & memcached as a cache store.

I use framgent caching in a partial and loop on a instance variable @recent_posts in my index view.
The problem, i think, is in my index action.
I didn't change anything to my code, so normally,my partial should be cached but the sql request that get my @recent_post should be processed.
Or it appears that the first request trigger the sql but the requests after wont.

To be a little more precise, my @recent_posts is defined by something like that.
@recent_post = SomeModel.first.get_last_posts.
And it appear that the SomeModel.first call is triggered every time but only the .get_last_post sql request won't be processed for the 2+ request...

Any though ?

Advanced Caching in Rails ... I'll just leave this here.

for the touch => true property in the association, is it possible to chain these together?

i.e.

class Article < ActiveRecord::Base
has_many :posts
end

class Post < ActiveRecord::Base
has_many :comments
belongs_to :posts, :touch => true
end

class Comment < ActiveRecord::Base
belongs_to :posts, :touch => true
end

in the above, if I do:
Comment.first.touch
will that touch the associated post AND article? (and therefore trigger a refresh on articles?)

hi, is there any way to encrypt on the way out / decrypt on the way in? i have sensitive info in my app that i'd like to ensure remains inaccessible to anyone who may connect to my memcache server.

def sweep not working for me.

this yes:

 def sweep(banner)
    ActionController::Base.new.expire_fragment("fragment_tabs-banners-parnaiba")
 end

Just had to add: ActionController::Base.new.expire_fragment

If anybody else wants to use caching in their decorators / presenters and use HAML, then this is how to do it:

include Haml::Helpers
def haml_cache(key, &block)
  self.init_haml_helpers
  buffer = haml_buffer.buffer
  h.with_output_buffer(buffer) do
    h.cache key do
      h.concat(yield)
    end
end

end

Heres a blog discussing implementation in rails 4 http://www.charliemassry.com/posts/52-caching-rails-views

Any best practices about how to test Fragment Caching?