Question

I want to upload and then process a file in a Ruby on Rails app. The file upload is usually quite short, but the server-side processing can take some time (more than 20 seconds) so I want to give the user some indicator – something better than a meaningless ‘processing…’ screen.

I’m trying to use the following code in the view

<%= periodically_call_remote(:url => {:action => 'progress_monitor', :controller => 'files'},                  :frequency => '5',                  :update => 'setProgress('progressBar','5')'                  ) %> 

The content of the :update parameter is the javascript I want to run every 5 seconds

and the following code is in the files controller

def progress_monitor   render :text => 'whatever' end 

Eventually the progress_monitor method will return the current progress as an integer (% complete) and that will be passed into the ‘setProgress’ JavaScript code (that will update an on screen element)

However, I’m struggling to get a correct response from from the server that can then be passed into JavaScript.

Can anyone help, or am I approaching this the wrong way?

There is a follow up question to this, I originally updated this question but the update was sufficiently different to warrant a new question, here.

Answer 1

periodically_call_remote() updates a div. It won’t call your JavaScript function. I’m no JavaScript guru, but to solve your problem, you should do your own xmlhttp call. If I were you, I’d use prototype’s AJAX request

http://www.prototypejs.org/api/ajax/request

and use JavaScript’s settimeout or setinterval to do the periodic polling

http://www.elated.com/articles/javascript-timers-with-settimeout-and-setinterval/

hope this helps cos actually I’ve encountered the same prb too =)