update_meta_cache

Update the metadata cache for the specified objects.

Description

(array|false) update_meta_cache( (string) $meta_type, (int|array) $object_ids );

Returns (array|false)

Metadata cache for the specified objects, or false on failure.

Parameters (2)

0. $meta_type (string): Type of object metadata is for (e.g., comment, post, or user)
1. $object_ids (int|array): Array or comma delimited list of object IDs to update cache for

Usage

if ( !function_exists( 'update_meta_cache' ) ) { 
    require_once ABSPATH . WPINC . '/meta.php'; 
} 
  
// Type of object metadata is for (e.g., comment, post, or user) 
$meta_type = ''; 
  
// Array or comma delimited list of object IDs to update cache for 
$object_ids = null; 
  
// NOTICE! Understand what this does before running. 
$result = update_meta_cache($meta_type, $object_ids);

Defined (1)

The function is defined in the following location(s).

/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); 
 
    $cache_key = $meta_type . '_meta'; 
    $ids = array(); 
    $cache = array(); 
    foreach ( $object_ids as $id ) { 
        $cached_object = wp_cache_get( $id, $cache_key ); 
        if ( false === $cached_object ) 
            $ids[] = $id; 
        else 
            $cache[$id] = $cached_object; 
    } 
 
    if ( empty( $ids ) ) 
        return $cache; 
 
    // Get meta info 
    $id_list = join( ', ', $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 ( $ids as $id ) { 
        if ( ! isset($cache[$id]) ) 
            $cache[$id] = array(); 
        wp_cache_add( $id, $cache[$id], $cache_key ); 
    } 
 
    return $cache; 
}