Rails%203%20In%20Action

Page and action caching
caches_action :show, :cache_path => (proc do
project_path(params[:id], :user_id => current_user.id)
end)
Here, you’ve passed the cache_path option to caches_action. This is a proc object,
and you need to wrap the value for this option in brackets or Ruby will think the block
is for the caches_action call.
This Proc object is evaluated within the context of an instance of this controller,
and therefore you’ll have access to the params and current_user methods usually
available within an action or a before_filter. With these, you’re building a string by
combining the URL of the current project (provided to you by the helper
project_path) and the id of current_user.
When you access this page again in the browser, Rails will re-process this action
because the cache path has changed and then save the page in a new location. In
the output for the server you’ll see this new fragment has been written, indicated by
this line:
Write fragment views/localhost:3000/projects/1/1 (4.4ms)
This time, the path to the file and the file itself have changed because you’ve changed
the URL of the page; it’s now the cached version of this page currently for this user.
When you sign out as your current user and sign in as the other user and navigate to
this project’s page, you’ll see that the “Signed in” message at the top of the page is
now the correct one, as shown in figure 16.9.
This means that you’ve now fixed the problem where the same cached page was
shown for all users, meaning that each of your users will see a slightly different version
of this page. This is almost right, but not quite. When you click the Next link for pagination,
you’ll still only be shown the first page. This is because much like
caches_page, your caches_action also ignores the page parameter.
You can fix this, however, by changing the path generated for the cached page to
contain the current page number. To do this, change this line in caches_action’s
cache_path option in ProjectsController
project_path(params[:id]) + "/#{current_user.id}"
Figure 16.9 Signed in as
admin for a cached page
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