wp_maybe_generate_attachment_metadata() │ WP 3.9.0

Creates attachment metadata if it is missing; otherwise, does nothing.

The function will add metadata to the meta-fields (see wp_update_attachment_metadata()), only if:

Metadata is not present yet - wp_get_attachment_metadata() returns nothing.
The file physically exists - the path for checking the file is obtained through get_attached_file().

Uses: get_attached_file(), wp_get_attachment_metadata(), wp_update_attachment_metadata(), wp_generate_attachment_metadata()

No Hooks.

Returns

null. Nothing.

Usage

wp_maybe_generate_attachment_metadata( $attachment );

$attachment(WP_Post) (required): The attachment object for which metadata needs to be generated.

Examples

#1 Generation of attachment metadata

This example shows how to create metadata for a file added to the media library. It assumes that the metadata was not created automatically for some reason (usually it is created automatically). If the data already exists (function wp_get_attachment_metadata() returns something), the function will simply do nothing.

$attachment = get_post( 123 );
wp_maybe_generate_attachment_metadata( $attachment );

Changelog

Since 3.9.0

Introduced.

`wp_maybe_generate_attachment_metadata() wp maybe generate attachment metadata` code ^{WP 6.9.1}

wp-includes/media.php

function wp_maybe_generate_attachment_metadata( $attachment ) {
	if ( empty( $attachment ) || empty( $attachment->ID ) ) {
		return;
	}

	$attachment_id = (int) $attachment->ID;
	$file          = get_attached_file( $attachment_id );
	$meta          = wp_get_attachment_metadata( $attachment_id );

	if ( empty( $meta ) && file_exists( $file ) ) {
		$_meta = get_post_meta( $attachment_id );
		$_lock = 'wp_generating_att_' . $attachment_id;

		if ( ! array_key_exists( '_wp_attachment_metadata', $_meta ) && ! get_transient( $_lock ) ) {
			set_transient( $_lock, $file );
			wp_update_attachment_metadata( $attachment_id, wp_generate_attachment_metadata( $attachment_id, $file ) );
			delete_transient( $_lock );
		}
	}
}