Question

I have a block

<% cache 'unique_key', 60.minutes.from_now do %>
  ...
  <% begin %>
    ...
  <% rescue %>
    ...
  <%end>
<% end %>

and I’m trying to make the implementation more robust by only caching (and thus allowing the user to see) the rescue message if there isn’t a previous value already in the cache. Currently, if the response in the begin block sends back an error for any reason, I’m caching the user viewed error message. I would prefer to fall back onto the old cached data. The problem that I can’t get past is –

Where is cache storing the data?

Every time I try Rails.cache.read 'unique_key', I get nil back. Is cache not storing the value in memcached? Is there a way that I can dump the cache to screen?

I couldn’t follow the rails source. It seemed to me the the fragment_for method in cache was a rails 3 thing, and thus, I didn’t debug further.

Answer 1

I solved this by using the fetch method. I used

<% Rails.cache.fetch('unique_key', :expires_in => 60.minutes){  
   begin
     ...
   rescue
     ...
   end
} %>

When I did this, I could successfully find the key. I’m still not sure why I couldn’t find the cached data after adding the fragment_cache_key that I found, but using Rails.cache.fetch seemed to do the trick.