How to use jQuery to remotely validate a field that depends on another field in the form?

Question

I have a form in which I am using remote validation to check if an email address already exists in the database. However, the catch is that on this form, the user can selec

Answer 1

From the second example for remote it looks like functions (evaluated during validation) can be used for data, so

remote: {
    url: 'remote_script.php',
    data: {
        group_id: function () {
            return $('select.group_id').val();
        }
    }
}

should work.

For your second question, did you try passing the validation rules to validate()?