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

Found the solution to the second part of my question:

 $(".email_addr").removeData("previousValue");

will remove the cache of the remote request, and allow the remote request to be triggered again, using .element().

Thus my code is as follows:

$("select.group_id").change(function() {
    $(".email_addr").removeData("previousValue"); //clear cache when changing group
    $("#customer_form").data('validator').element('.email_addr'); //retrigger remote call
    //my validator is stored in .data() on the form
});

Solution was found here: solution

The first part of my question was answered originally by @Jeffery To

All that needs to be done is to change the value of the parameter to a function, rather than just a value. Jeffery's example is copied below for future googlers:

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

Answer 2

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()?