Your remote_function or remote_form_tag could stop working if you use jQuery into your Ruby on Rails project. This is because the jQuery $ function is different from the prototype one, and RoR uses some particular function that is not available with jQuery.

For example, you can get an error like this submitting your remote_form_tag:

$(form).getElementsByTagName is not a function
http://localhost:3000/javascripts/prototype.js?1239274532
Line 3483

To solve this kind of problem, you have to use the jQuery no-conflict method, like explaned on the jQuery site. Simply add theese lines of code in your default layout between into a <script> tag:

jQuery.noConflict();
jQuery(document).ready(function($) {
})

Now, RoR can use prototype calling the default function $ and you can use jQuery using the jQuery function:

jQuery("#myId").hide("def");

If you create a scaffold for your rails project, it will create for you a lot of things; for example, a way to show your object in xml format. But what about adding custom elements to that xml?

I solved in this way:

class MyObject < ActiveRecord::Base
  #[...]
  def to_xml(options={})
    cp = attributes.clone
    cp["something"] = "some value"
    cp["another thing"] = self.some_relation.length
    cp.to_xml(options)
  end
end