Rails partial caching is showing view changes despite no model changes -

following guide "agile web development rails 4." covers caching product catalog re-render products changed.

i edited (config/environments/development.rb):

config.action_controller.perform_caching = true 

added code return updated product: (app/models/product.rb)

def self.latest   product.order(:updated_at).latest end 

lastly updated store index cache: (app/views/store/index.html.erb)

<h1>your pragmatic catalog</h1> <% cache ['store', product.latest] %>   <% @products.each |product| %>     <% cache ['entry', product] %>       <div class="entry">         <%= image_tag(product.image_url) %>         <h3><%= product.title %></h3>         <%= sanitize(product.description) %>         <div class="price_line">           <span class="price"><%= number_to_currency(product.price) %></span>         </div>       </div>     <% end %>   <% end %> <% end %> 

the book states way test if caching working change view did add lorem ipsum within 1 or both cache tags browser shows change on refresh... frustrating! clue?

your cache key collection not changing. happens because cache ['store', product.latest] not clever expect. if have @ log you'll see cache key used literal including activerecord::relation::products.

use last updated_at value cache ['store', product.latest.max(:updated_at)] better results.

in rails 5 easier due the addition of cache_key activerecord::relation few weeks ago.