gform_pre_render upon previous dropdown condition?

Hey guys, hope all is well at GF

I have a question regarding gform_pre_render?

I have dealer form. Which basically you choose your county, and then your dealer.

Dropdown A = Dealer Country
Dropdown B = Dealer Name

I have about 15 countries, and I am using get_terms in the gform_pre_render to list all my countries that I have assigned to a dealer...

// Dropdown A - Dealer Country
add_filter("gform_pre_render", "dropdown_dealer_country");
add_filter("gform_admin_pre_render", "dropdown_dealer_country");
function dropdown_dealer_country($form){

    if($form["id"] != 3)
       return $form;

    $terms = get_terms("dealer-country");

    $items = array();
    $items[] = array( "text" => __('Select country...','mission-theme'), "value" => 0 );

    foreach($terms as $term)
        $items[] = array( "text" => $term->name, "value" => $term->slug );

    foreach($form["fields"] as &$field)
        if($field["id"] == 6){
            $field["choices"] = $items;
        }

    return $form;
}

OK so the above works perfectly in Dropdown A

Now what I am trying to do in Dropdown B is display all my dealer names.

I have named each dealer custom post-type title with the name of the dealer, and this is what I am pre populating my secondary drop down with...

// Dropdown B - Dealer Name
add_filter("gform_pre_render", "dropdown_dealer_name");
add_filter("gform_admin_pre_render", "dropdown_dealer_name");
function dropdown_dealer_name($form){

    if($form["id"] != 3)
       return $form;

    $dealers = get_posts(array(
    	"post_type" => "dealer",
    	"dealer-country" => $dealerCounty,
    	"post_status" => "publish",
    	"orderby" => "title",
    	"order" => "ASC",
    	"posts_per_page"  => -1
    ));

    $items = array();
    $items[] = array( "text" => __('Select dealer...''mission-theme'), "value" => 0 );

    foreach($dealers as $dealer)
        $items[] = array( "text" => $dealer->post_title, "value" => $dealer->post_name );

    foreach($form["fields"] as &$field)
        if($field["id"] == 7){
            $field["choices"] = $items;
        }

    return $form;
}

...and as you can see in line 11, I have a variable in my get_posts array "dealer-country" => $dealerCounty

My question, is it some how posible to get the choice that is made in Dropdown A into my $dealerCounty variable in my Dropdown B function?

Any tips or help would be much appreciated as my Dropdown B is currently very long, and I need to filter it down by country.

Many Thanks
Josh

Great, I did just that, see code below I used. Thanks

Upon change of Dropdown A I have an ajax function request tha re-populated Downdown B with the filtered options based on the selection in Dropdown A.

See the ajax jquery script...

[php]
countryFilter = function () {
    	var countryClass = '.dealer-country select',
    		dealerClass  = '.dealer-name select';
    	$(countryClass).change(function(){
    		var countrySelect = $(this),
    			country = countrySelect.val(),
    	    	dealerSelect = countrySelect.parents('form').find(dealerClass);
    	 	if(country != "default") {
    	    	$.ajax({
    				type: 'POST',
    				url: '<?php echo admin_url('admin-ajax.php'); ?>',
    				data: { dealerCountry : country, action: 'get_dealer_name' },
    				success: function(data){
    					dealerSelect.empty();
    					var options = $.parseJSON(data);
    					for(i=0;i<options.length;i++){
    						dealerSelect.append('<option value="'+options[i].value+'">'+options[i].text+'</option>');
    					}
    					dealerSelect.removeAttr('disabled');
    				}
    	    	});
    	    }
    	});
    }

Which I fired using...

[js]
$(document).ready(function () {
    	countryFilter();
    });
    $(document).bind('gform_post_render', function(event, form_id){
    	if(form_id == 3) {
        	countryFilter();
    	}
    });

I then trimmed my original functions to...

[php]
// Dropdown A - Dealer Country
    add_filter("gform_pre_render", "dropdown_dealer_country");
    add_filter("gform_admin_pre_render", "dropdown_dealer_country");
    function dropdown_dealer_country($form){
            if($form["id"] != 3)
               return $form;
            $terms = get_terms("dealer-country");
            $items = array();
            $items[] = array( "text" => __('Select country...','theme'), "value" => 'default' );
            foreach($terms as $term)
        		$items[] = array( "text" => $term->name, "value" => $term->slug );
            foreach($form["fields"] as &$field){
                if($field["id"] == 6 ){
                    $field["cssClass"] = 'dealer-country';
                    $field["choices"] = $items;
                }
        	}
            return $form;
        }
        // Dropdown B - Dealer Name
    add_filter("gform_pre_render", "dropdown_dealer_name");
    add_filter("gform_admin_pre_render", "dropdown_dealer_name");
    function dropdown_dealer_name($form){
            if($form["id"] != 3)
               return $form;
            $items = array();
            $items[] = array( "text" => __('Select dealer...','theme'), "value" => 'default' );
            foreach($form["fields"] as &$field){
                if($field["id"] == 7){
        			$field["cssClass"] = 'dealer-name';
        			$field["choices"] = $items;
                }
        	}
            return $form;
        }

Then the finishing touch is the function which also goes in the functions.php - this is called by the ajax request...

[php]
function get_dealer_name_fn(){
    	$dealerCountry = $_POST['dealerCountry'];
    	$dealers = get_posts(array(
            "post_type" => "dealer",
            "dealer-country" => $dealerCountry,
            "post_status" => "publish",
            "orderby" => "title",
            "order" => "ASC",
            "posts_per_page"  => -1
    	));
    	$items = array();
    	$items[] = array( "text" => __('Select dealer...','theme'), "value" => 'default' );
    	foreach($dealers as $dealer){
    		$items[] = array( "text" => $dealer->post_title, "value" => $dealer->post_title );
    	}
    	echo json_encode($items);
    	die;
    }
    add_action('wp_ajax_get_dealer_name', 'get_dealer_name_fn');
    add_action('wp_ajax_nopriv_get_dealer_name', 'get_dealer_name_fn');