Question

I have some code like this:

<% cache "footer_links" do %>
  <%= cms_snippet_content('footer_links') %>
<% end %>

And I thought of writing a helper method, like this one:

def cached_snippet_content(snip_id)
  cache(snip_id) do
    cms_snippet_content(snip_id)
  end
end

However, I don’t get any output in my view, even though, my erb code looks like this:

<%= cached_snippet_content "footer_links" %>

What am I doing wrong?

Answer 1

May the source be with you, Luke:

# actionpack-3.2.0/lib/action_view/helpers/cache_helper.rb
def cache(name = {}, options = nil, &block)
  if controller.perform_caching
    safe_concat(fragment_for(name, options, &block))
  else
    yield
  end

  nil
end

This shows that cache is implemented to be called from ERB views, not from helpers. An alternative implementation:

def cache(name = {}, options = nil, &block)
  if controller.perform_caching
    fragment_for(name, options, &block)
  else
    capture(&block)
  end
end

And now use it with the new Rails ERB style (<%= … > even in blocks if they output something):

<%= cache "key" do %>
  <%= content_tag(:p, "hello") %>
<% end %>

I’d test this carefully, there may be hidden corners, I guess there’ll be a reason why cache has not been adapted to the Rails 3 block style.