Best way to combine fragment and object caching for memcached and Rails

Question

Lets say you have a fragment of the page which displays the most recent posts, and you expire it in 30 minutes. I\'m using Rails here.

<% cache(\"recent_posts         


        

Answer 1

You may also want to look into

Fragment Cache Docs

Which allow you to do this:

<% cache("recent_posts", :expires_in => 30.minutes) do %>
  ...
<% end %>

Controller

unless fragment_exist?("recent_posts")
  @posts = Post.find(:all, :limit=>20, :order=>"updated_at DESC")
end

Although I admit the issue of DRY still rears its head needing the name of the key in two places. I usually do this similar to how Lars suggested but it really depends on taste. Other developers I know stick with checking fragment exist.

Update:

If you look at the fragment docs, you can see how it gets rid of needing the view prefix:

# File vendor/rails/actionpack/lib/action_controller/caching/fragments.rb, line 33
def fragment_cache_key(key)
  ActiveSupport::Cache.expand_cache_key(key.is_a?(Hash) ? url_for(key).split("://").last : key, :views)
end