[S.O.S.] ActiveField: A source --> target field module via Drupal, Ajax, and jQuery

Hello fellow Drupalers,

I need help.
I am writing a module called "ActiveField". In summary, the purpose of this module is to (eventually) be able to define source fields in a CCK content type (e.g. "Location") and specify the target fields in another CCK content type (e.g. "Field Trip") that are updated based on the a user defined list or .sql query. The goal is to have this be done via Drupal Admin web interface
and to support a many to many relationship between source fields and target fields. The original blog article that
I wrote on this is located at: http://www.sageofcode.com/?p=59

I have ported this module over from Drupal 5.x to Drupal 6.x based on some great resources:
1. Pro Drupal Development, 2nd Ed. (http://www.drupalbook.com/)
2. Drupal 6 JavaScript and jQuery (http://www.packtpub.com/drupal-6-javascript-and-jquery/book)
3. Learning jQuery (http://www.packtpub.com/jQuery/book/mid/100407j4kh3d)
4. jQuery in Action (http://www.manning.com/bibeault/)
5. "Using Ajax in Drupal" 6 by Caroline Schnapp. (http://11heavens.com/using-ajax-in-Drupal-6)

Below is the source code. In short, the slippery bug that I am trying to squash has to do with the fact that the
$_GET[] array is not being updated with the values that are being sent down by the $.get() AJAX request
(which I can see via FireBug). I know the array is empty based on some code-level tests that I ran and the fact that when I append "/ActiveField/field-trip" to the site's url, the following is returned:

returns: { "one": null, "two": null }

Yes, I have a QA back ground ;-).

Once I get the basic version working (i.e. code level only), I will create a Contrib module project.

I have actually spent more hours debugging and than porting the code. :-(.

<<ActiveField.module>>

<?php
//$id$

/**
* @file
* A dynamic source-to-target field module via Drupal, Ajax, and jQuery
*
*/

/**
*
* Implementation of hook_perm().
* Adding the "Use ActiveField" permission to Drupal's role-based access control page.
* Prevents Anonymous use.
*
*/
function ActiveField_perm()
{
    return array('Use ActiveField');
}

/**
* Implementation of hook_menu()
* Allows for the mapping for jQuery intercepted URL to a Drupal PHP function
* The Drupal PHP function will return the child field's value(s) to jQuery in JSON
*/
function ActiveField_menu() 
{   
    $items['ActiveField/field-trip'] = array(
                         'page callback'      => 'ActiveField_getTargets',
                         'access arguments'   => array('Use ActiveField'),
                         'type'               => MENU_CALLBACK,
                        );

     return $items;
}


/**
*
* Implementation of hook_form_alter()
*
*/
function ActiveField_form_alter(&$form, $form_state, $form_id)
{
    
    if ($form_id == 'field_trip_type_node_form')
    {
        drupal_add_js(drupal_get_path('module', 'ActiveField') .'/ActiveField.js');                                            
    }
}

/**
*
* Called by jQuery
* Submits the source field value and returns the target field's value(s) as a JSON
*/
function ActiveField_getTargets()
{   

    // Getting the value of the Date source feild
    // NOTE: .sql queries are not being generated based on this field yet.
    $field_date_1_value  = check_plain($_GET['sDate']);

    // Getting the value of the location source feild and the node id of the corresponding content type
    $location_value = check_plain($_GET['sLocation']);
    $sql_location ="SELECT nid FROM {node} WHERE title='$location_value'";
    $nid_location = db_result(db_query($sql_location));


    // SQL query for getting target field one's value (i.e. sunrise)
    $sql_sunrise="SELECT field_sun_rise_value FROM {content_field_sunrise} WHERE  nid = '$nid_location'";


    // SQL query for getting target field two's value (i.e. sunset)
    $sql_sunset="SELECT field_sun_set_value FROM {content_field_sunset} WHERE  nid = '$nid_location'";


    // Getting Target Field one's value (i.e. sunrise)
    $results_sunrise = db_query($sql_sunrise);
    while ($data = db_fetch_object($results_sunrise)) 
    {

        $result1 = $data-> field_sun_rise_value;
    }


    // Getting Target Fields two's value (i.e. sunset)
    $results_sunset = db_query($sql_sunset);
    while ($data = db_fetch_object($results_sunset)) 
    {
        $result2 = $data-> field_sun_set_value;
    }

                        
    // Returning Target Fields' values to jQuery as a JSON
    print drupal_json(array (

                              'one' => $result1,
                              'two' => $result2

                             )

                      );

    exit();

}

<<ActiveField.js>>

/** ActiveField.js
*
* JavaScript file with jQuery
* Used by ActiveField.module
*
*/

//$Id$

if(Drupal.jsEnabled)
{
    $(document).ready(function()
		      {
                          // Source field & respective event    
                          // Adding change event to source Field
                          $('#edit-field-location-value').change(function(event)
                                  {

                                    // Getting source fields' values
                                    var SourceDate     = $('#edit-field-date-0-value-datepicker-popup-0').val();
                                    var SourceLocation = $('#edit-field-location-value').val();                                                            
                                             

                                     //AJAX call
                                     $.get('ActiveField/field-trip', 
                                     {sDate: SourceDate, sLocation: SourceLocation}, 
                                     function (json) 
                                     {

                                       // Setting tareget fields' values                                                                                                    
                                       $('#edit-field-sun-rise-0-value').val(json.one); 
                                       $('#edit-field-sun-set-0-value').val(json.two);
                                                                                                      
                                                                    
                                     }

            
                                     );
							

                                     // preventing entire page from reloading

                                    return false;
                                    }
                            ); 

                       }
    );	

}