UJS partial rendering in Rails 3

Question

I'm struggling to get my head around how to implement UJS in Rails (specifically, Rails 3 with jQuery). I've worked through Ryan's Railscast, and can follow what to do when submitting a form via AJAX, but I'm having trouble extending this concept to attaching a javascript function to a html element in my view files. Ultimately, I would like to be able to create a form where a different partial is rendered depending upon which radio button from a series is selected. Should I be looking at using the Prototype legacy helpers for this? And when do I need to create a .js.erb file?

Sorry for the newbie question, I've been unable to find much that explicitly outlines the concept of UJS and how to use it in a Rails app/switch over code from a RJS approach. Any help would be much appreciated!

Answer 1

By using the remote => true on the form, your data will go to the server and all javascript returned will simply be executed in the context of the page, so here is a simple example:

<%= form_tag '/action_path', :remote => true do %>
  <%= radio_button_tag 'partial', 'one' %>
  <%= radio_button_tag 'partial', 'two' %>
  <%= submit_tag 'select' %>
<% end %>

<div id="partial_holder">

</div>

On the server

def action
  #do whatever you want with parameters
end

On the action.js.erb file

$('#partial_holder').html("<%= escape_javascript(render(:partial => params[:partial])) %>")

Answer 2

On the action.js.erb file

$('#partial_holder').html(<%= escape_javascript(render(:partial => params[:partial])) %>)

The above line has a minor mistake, the ruby tags inside html method should be inside quotes. The following will work.

$('#partial_holder').html("<%= escape_javascript(render(:partial => params[:partial])) %>")