ruby on rails - Etags in Controller -


every rails etag example i've seen has been simple fresh_when method being called last line in controller. i'm trying understand how fresh_when method works controller has resource intensive method calls don't want call in request if page still fresh. example,

class notescontroller < applicationcontroller   etag { current_user.try :id }    def show     @note = note.find(params[:id])     @note.do_some_expenisve_data_manipulation     fresh_when(@note)   end end

will @note.do_some_expensive_data_manipulation called if note hasn't been updated since last time user updated it? if placed line below fresh_when called? thanks!

i feel using stale? easier me understand fresh_when. here example.

if stale?(etag: @note, last_modified: @note.updated_at)   respond_to |format|     format.html {       // expensive work here     }   end end

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