Question

I have an action that takes a long time. I want to be able to provide updates during the process so the user is not confused as to whether he lost the connection or something. Can I do something like this:

class HeavyLiftingController < ApplicationController
  def data_mine
    render_update :js=>"alert('Just starting!')"
    # do some complicated find etc.
    render_update :js=>"alert('Found the records!')"
    # do some processing ...
    render_update :js=>"alert('Done processig')"
    # send @results to view
  end
end

Answer 1

It is impossible to handle the request that way. For each request, you have just one answer.

If your action takes a long time, then maybe it should be performed asynchronously. You could send user e-mails during the process to notify him of the progress.

I suggest that you to take a look on DelayedJob gem:
http://rubygems.org/gems/delayed_job

It will handle most difficult parts of dealing with assync stuff for you (serializing / deserializing your objects, storage, so on…).

Hope it helps you!