get_post_meta unserialize issue - retuns boolean(false)

Question

I´m using a simple custom plugin that parses and saves external XML data as a serialized array in a custom field. This works fine, however, when I update the post, instead of the array I only see a message saying: "bool(false)". I guess it has to with serialize / unserialize but didn't find any clues.

I needed to serialize when I update post meta using update_post_meta($post_id, 'tb_data', serialize($new_value_array)); By omitting serialize like update_post_meta($post_id, 'tb_data', $new_value_array); doesn't store any data in custom field. Furthermore, I have to use maybe_unserialize(get_post_meta($post->ID, 'tb_data', true)); to print the results.

There are 2 custom fields, (1) tb_item_group_id and (2) tb_data. Value of tb_data will be added using the below function,

Function I am using to update post meta is as below.

function parse_file_func($title) {
    // get_tickets_array();exit;
    $language = explode('-', get_bloginfo('language'));
    $language = $language[0];
    $file = file_get_contents('https://dl.dropboxusercontent.com/u/12344450/feed.xml');
    if (!$file) {
        exit;
    }
    $domObj = new xmlToArrayParser($file);
    $domArr = $domObj->array;
    if (($domObj->parse_error)) {
        echo $domObj->get_xml_error();
    } else {
        $first = $domArr['rss']['channel']['item'];
        foreach ($first as $item) {
            if ($item['languageCode'] == $language) {
                $args = array(
                    'meta_key' => 'tb_item_group_id',
                    'meta_value' => $item['g:item_group_id'],
                    'post_type' => 'tickets',
                );
                $post = get_posts($args);
                if (empty($post)) {
                    continue;
                } else {
                    $args = array(
                        'meta_key' => 'tb_item_group_id',
                        'meta_value' => $item['g:item_group_id'],
                        'post_type' => 'tickets',
                    );
                    $post = get_posts($args);
                    $post_id = $post[0]->ID;
                    $meta_values = get_post_meta($post_id, 'tb_data');
                    if (empty($meta_values)) {
                        $new_value_array = array();
                        unset($item['cdata']);
                        $new_value_array['tb_' . $item['g:item_group_id'] . '_' . $item['ticketID']] = $item;
                    }
                    else {
                        $meta_arrays = unserialize($meta_values[0]);
                        $new_value_array = $meta_arrays;
                        foreach ($meta_arrays as $meta_ticketbar => $tb_content) {
                            if ($meta_ticketbar == 'tb_' . $item['g:item_group_id'] . '_' . $item['ticketID']) {
                                unset($item['cdata']);
                                $new_value_array[$meta_ticketbar] = $item;
                            } else {
                                $new_value_array = $meta_arrays;
                                unset($item['cdata']);
                                $new_value_array['tb_' . $item['g:item_group_id'] . '_' . $item['ticketID']] = $item;
                            }
                        }
                    }
                    update_post_meta($post_id, 'tb_data', serialize($new_value_array));
                    // update_post_meta($post_id, 'tb_data', base64_encode($new_value_array));
                }
            } else {
                continue;
            }
        }
    }
}

and displaying on front-end using get_post_meta

<?php
    // $tb_meta = get_post_meta($post->ID, 'tb_data', true);
    $tb_meta = get_post_meta($post->ID, 'tb_data', true);
    $tb_meta_unserialized = maybe_unserialize( $tb_meta );
?>
<pre><?php
    // print_r ($tb_meta_unserialized);
    var_dump($tb_meta_unserialized);
?></pre>

Answer 1

I have managed to fix it at my own.

I have used following code to update post meta

update_post_meta($post_id, 'tb_data', base64_encode(serialize($new_value_array)));

...and following code to get post meta

$tb_meta = get_post_meta($post->ID, 'tb_data', true);
$tb_meta_unserialized = unserialize(base64_decode($tb_meta));

I hope this will help someone.

Answer 2

For me it was a simple stupid thing: When calling the post id you should not used an "echoed" return:

Within the loop inside get_post_meta() you have to use get_the_ID() instead of the_ID().

Calling get_post_meta(the_ID(), $key, true) will return boolean(false) because the ID is not a valid (can we say that?) post id.

Hope it helps someone not to waste 30 minutes on this like me.