How do I get jQuery-validate to work with Rails 3?

My Rails form code is as follows:

<%= form_for(resource, :as => resource_name, :url => session_path(resource_name)) do |f| %>
        <%= f.text_field :f_name, :value => "First Name", :class => "clearField curved" %><br />
        <%= f.text_field :l_name, :value => "Last Name", :class => "clearField curved" %><br />
        <%= f.text_field :username, :value => "Username", :class => "clearField curved" %><br />
        <%= f.password_field :password, :value => "Password", :class => "clearField curved" %><br />
        <%= f.password_field :password_confirmation, :value => "Password", :class => "clearField curved" %><br />开发者_JS百科;
        <%= f.text_field :email, :value => "Email Address", :class => "clearField curved" %><br />

    <div id="login_buttons">
        <%= f.submit "Sign in", :id => "login", :value => "Submit", :class => "curved" %>
        <%= f.submit "Sign in", :id => "register", :value => "Register", :class => "curved" %>
        <%= f.submit "Send Reset Instructions", :id => "pass-reset", :value => "Send Reset Instructions", :class => "curved"%>
        <a href="#" id="forgot-pw">Forgot pass?</a>
    </div>

<% end %>

What happens is when the page is loaded the first time, the user only sees the username & password field. Once they press 'Register' they then see the other fields. So what I would like to do is have form validation on both states. The login state (with just the username & password) and the registration state (with all the fields).

The HTML output produced is as follows:

<form accept-charset="UTF-8" action="/users/login" class="user_new" id="user_new" method="post"><div style="margin:0;padding:0;display:inline"><input name="utf8" type="hidden" value="&#x2713;" /><input name="authenticity_token" type="hidden" value="5B04HFtyauEPUigmXrIhi2jYvHJv47gvIgUbx64QQ0E=" /></div> 
        <input class="clearField curved" id="user_f_name" name="user[f_name]" size="30" type="text" value="First Name" /><br /> 
        <input class="clearField curved" id="user_l_name" name="user[l_name]" size="30" type="text" value="Last Name" /><br /> 
        <input class="clearField curved" id="user_username" name="user[username]" size="30" type="text" value="Username" /><br /> 
        <input class="clearField curved" id="user_password" name="user[password]" size="30" type="password" value="Password" /><br /> 
        <input class="clearField curved" id="user_password_confirmation" name="user[password_confirmation]" size="30" type="password" value="Password" /><br /> 
        <input class="clearField curved" id="user_email" name="user[email]" size="30" type="text" value="Email Address" /><br /> 

    <div id="login_buttons"> 
        <input class="curved" id="login" name="commit" type="submit" value="Submit" /> 
        <input class="curved" id="register" name="commit" type="submit" value="Register" /> 
        <input class="curved" id="pass-reset" name="commit" type="submit" value="Send Reset Instructions" /> 
        <a href="#" id="forgot-pw">Forgot pass?</a> 
    </div> 

I tried the following but it didn't work:

$('#user_new').validate({
    debug: true,
    rules: {
        user_username: "required",
        user_email: {
            required: true,
            email: true
        }
    },
    messages: {
        user_username: "Please specify your name",
        user_email: {
            required: "We need your email address to contact you",
            email: "Your email address must be in the format of name@domain.com"
        }
    }
});

So would love any advice on how I can get this going.

Edit1: Any thoughts or possible solutions?

This has been answered here:

How do I do client-side form validation in jQuery?

and originally here:

How to use jquery.validate plugin in cakephp form