Update some part of view(div) as progress of controller's action in Rails.

Question

I have div tag named update_info in the view my_view.html.erb and update action takes several minute to complete in the controller my_controller.rb.

I'd like to update update_info div tag every seconds as update action's progress.

How can I do this?

Is it possible update view from the action's loop? Or using Ajax?, if so, how can I access to server-side data and where is the data stored?(I don't know much about Ajax, please explain using Rails' Ajax helper methods if needed)

Tell me detail plz. thanks.

Answer 1

You can use partials for updating certain div. You can call controller through ajax. and then render your output using partial.

render :partial => "partial_name", :layout => false, :locals => {:local_var => xyz}

Note : partial name start with '_'

Answer 2

A comment first: you should avoid having several minutes requests (you should use background processing).

Now, depending of what you are actually doing in that request, the standard method is to interrogate the server (throught an ajax repetitive request, other than the current request) about the progress of current task. You can do this by using the periodically_call_remote function.

To have an idea:

In your view:

<%= periodically_call_remote(
   :condition => "check_var == false",
   :frequency => 3,
   :url => { :action => "evaluate_progress" }) %>

In your controller:

def evaluate_progress
  # replace it with code that actually computes the progress
  done = 0.6
  render :update do |page|
    if(done == 1)
      page << "check_var = false" #To stop querying the server
    else 
      page << "check_var = true"
      page.replace_html('your_div_id', "The task is #{done*100}% complete.")
    end
  end
end

Again, this is just a proof of concept, i haven't tested it. The actual code depends also on what you are actually doing in the long-lasting request.