Source
File: wp-includes/meta.php
function update_meta_cache( $meta_type, $object_ids ) {
global $wpdb;
if ( ! $meta_type || ! $object_ids ) {
return false;
}
$table = _get_meta_table( $meta_type );
if ( ! $table ) {
return false;
}
$column = sanitize_key( $meta_type . '_id' );
if ( ! is_array( $object_ids ) ) {
$object_ids = preg_replace( '|[^0-9,]|', '', $object_ids );
$object_ids = explode( ',', $object_ids );
}
$object_ids = array_map( 'intval', $object_ids );
/**
* Short-circuits updating the metadata cache of a specific type.
*
* The dynamic portion of the hook, `$meta_type`, refers to the meta object type
* (post, comment, term, user, or any other type with an associated meta table).
* Returning a non-null value will effectively short-circuit the function.
*
* @since 5.0.0
*
* @param mixed $check Whether to allow updating the meta cache of the given type.
* @param int[] $object_ids Array of object IDs to update the meta cache for.
*/
$check = apply_filters( "update_{$meta_type}_metadata_cache", null, $object_ids );
if ( null !== $check ) {
return (bool) $check;
}
$cache_key = $meta_type . '_meta';
$non_cached_ids = array();
$cache = array();
$cache_values = wp_cache_get_multiple( $object_ids, $cache_key );
foreach ( $cache_values as $id => $cached_object ) {
if ( false === $cached_object ) {
$non_cached_ids[] = $id;
} else {
$cache[ $id ] = $cached_object;
}
}
if ( empty( $non_cached_ids ) ) {
return $cache;
}
// Get meta info.
$id_list = join( ',', $non_cached_ids );
$id_column = ( 'user' === $meta_type ) ? 'umeta_id' : 'meta_id';
$meta_list = $wpdb->get_results( "SELECT $column, meta_key, meta_value FROM $table WHERE $column IN ($id_list) ORDER BY $id_column ASC", ARRAY_A );
if ( ! empty( $meta_list ) ) {
foreach ( $meta_list as $metarow ) {
$mpid = intval( $metarow[ $column ] );
$mkey = $metarow['meta_key'];
$mval = $metarow['meta_value'];
// Force subkeys to be array type.
if ( ! isset( $cache[ $mpid ] ) || ! is_array( $cache[ $mpid ] ) ) {
$cache[ $mpid ] = array();
}
if ( ! isset( $cache[ $mpid ][ $mkey ] ) || ! is_array( $cache[ $mpid ][ $mkey ] ) ) {
$cache[ $mpid ][ $mkey ] = array();
}
// Add a value to the current pid/key.
$cache[ $mpid ][ $mkey ][] = $mval;
}
}
foreach ( $non_cached_ids as $id ) {
if ( ! isset( $cache[ $id ] ) ) {
$cache[ $id ] = array();
}
wp_cache_add( $id, $cache[ $id ], $cache_key );
}
return $cache;
}