Rails cache ActiveRecord result

Question

My current homepage displays all available categories and all of the number of posts each category has. This of course is having a performance hit on the website and i was just wondering if this could be cached at all?

I don't mind if the cache is a little out of date and if the number of posts isn't 100% accurate at every refresh, but i would like it to only make the query every 30 minutes or so.

Answer 1

In Rails you can cache pretty much everything.

You can cache partials or queries. And you can expire them manually too.

For example

cache('categorylist') do
     render partial: 'such'
end

And in the post.rb model, after each create of post, reset this and force it to evaluate on next run

after_create {
    Rails.cache.delete('categorylist')
}

This way, your partial will only be evaluated (and written to cache) when a new post has been created. All other times, it will be fetched from cache.