Speed up Rails controller speed easily

When we adding a Rails controller action, especially for #show. Usually it would be like this:

def show 
  post = Post.find(params[:id])
  render json: post
end

It would hit our database everytime there is a request to that action. So what we can do is we cache the Post model into Cachestore.

Usually I use identity_cache gem for that. It uses Memcached as a datastore. So it would be like this if using IdentityCache gem:

def show 
  post = Post.fetch(params[:id])
  render json: post
end

Another optimization is we can add expiry tag

def show 
  post = Post.fetch(params[:id])
  return unless stale?(post)

  render json: post
end

See more about IdentityCache at: https://github.com/Shopify/identity_cache