WordPress rename attachment file with working thumbnails

The reason your code doesn't work is not related to the GUID.

It is because, in WP core, the function wp_update_attachment_metadata() is called with the original file name at the end of the media upload request handling. And the hook add_attachment is called inside wp_insert_attachment() function.

function media_handle_upload( $file_id, $post_id, $post_data = array(), $overrides = array( 'test_form' => false ) ) {    ... ...    // Save the data.    $attachment_id = wp_insert_attachment( $attachment, $file, $post_id, true );    if ( ! is_wp_error( $attachment_id ) ) {        // Set a custom header with the attachment_id.        // Used by the browser/client to resume creating image sub-sizes after a PHP fatal error.        if ( ! headers_sent() ) {            header( 'X-WP-Upload-Attachment-ID: ' . $attachment_id );        }        // The image sub-sizes are created during wp_generate_attachment_metadata().        // This is generally slow and may cause timeouts or out of memory errors.        wp_update_attachment_metadata( $attachment_id, wp_generate_attachment_metadata( $attachment_id, $file ) );    }    return $attachment_id;}

We can use the "wp_update_attachment_metadata" filter to change the metadata with the new file name.

Please check the below code. I tested and it is working well.

class CustomAttachmentRename {    public $new_filename = 'custom file';    private $new_path;    function __construct () {        add_action("add_attachment", array($this, "rename_attachment"), 10, 1);         }    function rename_attachment($post_id) {        // Get path info of orginal file        $og_path = get_attached_file($post_id);        $path_info = pathinfo($og_path);        // Santize filename        $safe_filename = wp_unique_filename($path_info['dirname'], $this->new_filename);        // Build out path to new file        $this->new_path = $path_info['dirname']. "/" . $safe_filename . "." .$path_info['extension'];                // Rename the file and update it's location in WP        rename($og_path, $this->new_path);            update_attached_file( $post_id, $this->new_path );        // Register filter to update metadata.        add_filter('wp_update_attachment_metadata', array($this, 'custom_update_attachment_metadata'), 10, 2);    }    function custom_update_attachment_metadata($data, $post_id) {        return wp_generate_attachment_metadata($post_id, $this->new_path);    }}$customAttachmentRename = new CustomAttachmentRename();$customAttachmentRename->new_filename = "test image" . time();

I turned @chengmin answer into a single function like this:

/*** Renames a file. Will also regenerate all the thumbnails that go with the file.* @SEE https://stackoverflow.com/questions/64990515/wordpress-rename-attachment-file-with-working-thumbnails** @param string $post_id The WordPress post_id for the attachment* @param string $new_file_name The filename (without extension) that you want to rename to*/  function attachment_rename($post_id, $filename) {    // Get path info of orginal file    $og_url = wp_get_attachment_url($post_id);    $og_path = get_attached_file($post_id);    $path_info = pathinfo($og_path);    $og_meta = get_post_meta($post_id, '_wp_attachment_metadata', true);    // Santize filename    $safe_filename = wp_unique_filename($path_info['dirname'], $filename);    // Build out path to new file    $new_path = $path_info['dirname']. "/" . $safe_filename . "." .$path_info['extension'];        // Rename the file in the file system    rename($og_path, $new_path);     // Delete old image sizes if we have them    if( !empty($og_meta) ) {        delete_attachment_files($post_id);    }    // Now save new path to file in WP    update_attached_file( $post_id, $new_path );    // Register filter to update metadata    $new_data = wp_generate_attachment_metadata($post_id, $new_path);        return add_filter('wp_update_attachment_metadata', function($data, $post_id) use ($new_data) {                return $new_data;    }, 10, 2);}/** * Delete all old image files, if they aren't used post_content anywhere.  * The dont-delete check isn't perfect, it will give a lot of false positives (keeping more files than it should), but it's best I could come up with. * @SEE https://github.com/WordPress/WordPress/blob/f4cda1b62ffca52115e4b04d9d75047060d69e68/wp-includes/post.php#L5983 * * @param string $post_id The WordPress post_id for the attachment */ function delete_attachment_files($post_id) {        $meta = wp_get_attachment_metadata( $post_id );    $backup_sizes = get_post_meta( $post_id, '_wp_attachment_backup_sizes', true );    $file = get_attached_file( $post_id );       $url = wp_get_attachment_url($post_id);        // Remove og image so it doesn't get deleted in wp_delete_attachment_files()    $meta['original_image'] = "";        // Check if image is used in a post somehwere    $url_without_extension = substr($url, 0 , (strrpos($url, ".")));    $args = [        "s" => $url_without_extension,        "posts_per_page" => 1,        "post_type" => "any"    ];    $found = get_posts($args);    if( empty($found) ) {        return wp_delete_attachment_files( $post_id, $meta, $backup_sizes, $file );    }    return false;}