Getting the post_id in wp_ajax function

Question

I wrote a custom AJAX function in which I have assigned a post type to be a child of another post type. In one function I am looping through those child posts, and I want to update the database to reflect the post_parent(the post which the child posts belong to). Problem is, I cannot grab that post's ID from anywhere to update the db. Any suggestions?

Here is the jQuery function:

    $.ajax({
                        url: ajaxurl,
                        type: 'POST',
                        async: true, 
                        cache: false,
                        dataType: 'json',
                        data:{
                                action: 'new_item_save',
                                item_order: $('#img-sortable').sortable('toArray').toString()

                        }
    });

And here is the PHP callback:

function save_new_img_order($post) {
global $wpdb;
$pid = $post->ID;

$order = explode(',', $_POST['item_order']);
$counter = 0;
foreach ($order as $item_id) {
    $wpdb->update($wpdb->posts, array( 'menu_order' => $counter, 'post_parent' => $pid ), array( 'ID' => $item_id ) );
    $counter++;
}
die(1);
}
add_action('wp_ajax_new_item_save', 'save_new_img_order');

Thanks in advance for any pointers!

Answer 1

The ajax hook won't pass back a $post object to your callback - how on earth would it know to do so!

You need to send the data yourself:

data:{
    action: 'new_item_save',
    post_id: POST_ID_EITHER_PARSED_FROM_DOM_OR_PHP_ECHOED,
    item_order: $('#img-sortable').sortable('toArray').toString()
}

...and then grab it from $_POST in your handler:

function save_new_img_order() {
    $post_id = $_POST['post_id'];
    ...
}