Submit form to db

Question

I am unable to get this insert to db function to work using ajax and a form. When I execute this, I receive a blank alert box on success.

HTML

<div id="rsvpContent">  
     <form id="Attendevent" action="">
     <input id="attend" name="attend" type="checkbox" value="yes" /><label for="attent">Yes, I plan to attend.</label>
     <input type="hidden" value="<?php echo get_the_ID(); ?>" name="event_id"/>
     <input type="hidden" value="<?php echo $current_user->ID; ?>" name="user_id"/>
     </form>
</div>

PHP

 add_action('wp_ajax_Attending', 'eventAttend');
 add_action('wp_ajax_nopriv_Attending', 'eventAttend');

 function eventAttend() {
  global $wpdb;

  $fields = array();
  parse_str($_POST['data'], $fields);

if($fields['attend'] == 'yes') {

   $wpdb->insert('wp_event_attendants', array( 'event_id' => $fields['event_id'], 'user_id' => $fields['user_id'])); 

    echo $wpdb->print_error();
    }
    echo 'Not working.';
   die();
}

JS (In header.php)

    $("#attend").click(function(){
    var form = $("#Attendevent").serialize();

    $.ajax({
      url: "<?php echo admin_url('admin-ajax.php'); ?>",
      beforeSend: function() {
          alert(form);
      },
      type:'POST',
      data:{
          action: "Attending",
          "data": form 
          },
      dataType:  'html',
      success: function(data) {
            alert(data);
      }
    }); 
});

DEBUGGING INFO

[07-Mar-2013 17:47:09] PHP Notice: Undefined index: attend in /wp-content/plugins/event-calendar-reg/functions.php on line 198

Answer 1

You are serializing your form data before posting it to your PHP function, but you do not unserialize it at the other end. Therefore your check for $_POST['attend'] == 'yes'will always fail.

Try the following (untested).

    function eventAttend() {
    $fields = array( );
    parse_str( $_POST['data'], $fields );
               if($fields['attend'] == 'yes') {

global $wpdb;

                    $wpdb->insert('wp_event_attendants', array( 'event_id' => $fields['event_id'], 'user_id' => $fields['user_id'])); 

                    echo $wpdb->print_error();
                }
     die();
    }