Returns metadata for current WordPress attachment or array of attachments

function-wp_get_attachment_meta.php

<?php

/**
 * Returns metadata for current WordPress attachment or array of attachments
 *
 * Reads all attachment metadata and expands it. URLs are rewritten with upload
 * dir prepended, file size is calculated if function exists. By default url protocol
 * is removed, use `add_filter()` to disable.
 *
 * @uses    {@link apply_filters() http://codex.wordpress.org/Function_Reference/apply_filters}
 * @uses    {@link file_size_format() https://gist.github.com/attitude/5964642}
 *
 * @param   int|array   $id     Array of IDs or a single id
 * @returns array               Attachment metadata
 *
 */
function wp_get_attachment_meta($id)
{
    if (is_array($id)) {
        $files = array();

        // Apply intval() on each array item
        $id = array_map('intval', $id);

        // Prefetch data, should minimize queries needed
        update_meta_cache('post', $id);

        foreach ($id as $the_id) {
            if ((int) $the_id > 0) {
                $files[] = wp_get_attachment_meta($the_id);
            }
        }

        return $files;
    }

    static $uploadpath = null;
    static $uploadurl  = null;

    if (!$uploadpath) {
        $upload_path = wp_upload_dir();
        if (!$upload_path || !isset($upload_path['path'])) {
            exit('Cannot continue. Upload path is not set correctly');
        }

        $uploadurl  = !! apply_filters('wp_get_attachment_meta/remove_protocol', true) ? strtr($upload_path['baseurl'], array('http:' => '', 'https:' => '')) : $upload_path['baseurl'];
        $uploadpath = $upload_path['basedir'];

        unset($upload_path);
    }

    $metadata = get_post_meta($id);

    foreach ($metadata as $metakey => &$meta) {
        $new_metadata[str_replace('_wp_attached_', '', str_replace('_wp_attachment_', '', $metakey))] = maybe_unserialize($meta[0]);
    }

    if (isset($new_metadata['metadata']) && isset($new_metadata['metadata']['sizes']) && class_exists('BetterWPMedia')) {
        $new_metadata['metadata'] = BetterWPMedia::generate_and_clean($new_metadata['metadata'], $id);
    }

    if (isset($new_metadata['file']) && (!isset($new_metadata['file_size']) || (function_exists('file_size_format') && !isset($new_metadata['file_size_formatted'])))) {
        $path_to_file = realpath($uploadpath.'/'.$new_metadata['file']);
        if ($path_to_file) {
            $file_size = filesize($path_to_file);

            $new_metadata['file_size'] = $file_size;
            update_post_meta($id, '_wp_attached_file_size', $new_metadata['file_size']);

            if (function_exists('file_size_format')) {
                $new_metadata['file_size_formatted'] = file_size_format($file_size);
                update_post_meta($id, '_wp_attached_file_size_formatted', $new_metadata['file_size_formatted']);
            }
        }
    }

    if (isset($new_metadata['file'])) {
        $new_metadata['metadata']['file'] = $uploadurl.'/'.$new_metadata['file'];
        $new_metadata['guid'] =& $new_metadata['metadata']['file'];
        $new_metadata['file'] =& $new_metadata['metadata']['file'];
    }

    if (isset($new_metadata['metadata']) && isset($new_metadata['metadata']['sizes'])) {
        global $_wp_additional_image_sizes;

        foreach ($new_metadata['metadata']['sizes'] as $size => &$sizedata) {
            $sizedata['file'] = dirname($new_metadata['file']).'/'.$sizedata['file'];
            $sizedata['img']  = wp_get_attachment_image($id, $size);
        }
    }

    $new_metadata['id'] = $id;

    return $new_metadata;
}