I have a rails 4.1 app, that on a particular page retrieves a list of orders and lists them out in a table. It's important to note that the list is different depending on the logged in user.
To improve performance of this, I am looking to cache the partials for each order row. I am considering to do it like this:
_order_list.html.erb
<% cache(@orders) do %>
<%= render @orders %>
<% end %>
_order.html.erb
<% cache(order) do %>
...view code for order here
<% end %>
However, I'm unsure about the caching of the collection (@orders). Will all users then be served the same set of cached @orders (which is not desired)?
In other words, how can I ensure to cache the entire collection of @orders for each user individually?
Will all users then be served the same set of cached @orders (which is not desired)?
Actually cache_digests does not cache @orders themselves. It caches html part of the page for a particular given object or set of objects (e.g. @orders). Each time a user asks for a webpage, @orders variable is going to be set in controller action and its digest is compared to the cached digest.
So, assuming we retrieve @orders like this:
def index
@orders = Order.where(:id => [1,20,34]).all
end
What we gonna get is cached view with a stamp like that:
views/orders/1-20131202075718784548000/orders/20-20131220073309890261000/orders/34-20131223112753448151000/6da080fdcd3e2af29fab811488a953d0
Note that ids of retrieved orders are mentioned in that stamp, so each user with his/her own unique set of orders should obtain his/her own individual cached view.
But here comes some great downsides of your approach: