Filters values for the meta key dropdown in the Custom Fields meta box.

Returning a non-null value will effectively short-circuit and avoid a potentially expensive query against postmeta.

$keys array|null

Pre-defined meta keys to be used in place of a postmeta query. Default null.

$post WP_Post

The current post object.

File: wp-admin/includes/template.php. View all references

$keys = apply_filters( 'postmeta_form_keys', null, $post );