get_metadata

Retrieve metadata for the specified object.

Description

get_metadata( (string) $meta_type, (int) $object_id, (string) $meta_key = '', (constant) $single = false ); 

Parameters (4)

0. $meta_type (string)
Type of object metadata is for (e.g., comment, post, or user)
1. $object_id (int)
ID of the object metadata is for
2. $meta_key — Optional. (string) => ''
Metadata key. If not specified, retrieve all metadata for the specified object.
3. $single — Optional. (constant) => false
Optional, default is false. If true, return only the first value of the specified meta_key. This parameter has no effect if meta_key is not specified.

Usage

  1. if ( !function_exists( 'get_metadata' ) ) { 
  2.     require_once ABSPATH . WPINC . '/meta.php'; 
  3. } 
  4.   
  5. // Type of object metadata is for (e.g., comment, post, or user) 
  6. $meta_type = ''; 
  7.   
  8. // ID of the object metadata is for 
  9. $object_id = -1; 
  10.   
  11. // Optional. Metadata key. If not specified, retrieve all metadata for 
  12. // the specified object. 
  13. $meta_key = ''; 
  14. $single = false; 
  15.   
  16. // NOTICE! Understand what this does before running. 
  17. $result = get_metadata($meta_type, $object_id, $meta_key, $single); 
  18.     

Defined (1)

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

/wp-includes/meta.php  
  1. function get_metadata($meta_type, $object_id, $meta_key = '', $single = false) { 
  2.     if ( ! $meta_type || ! is_numeric( $object_id ) ) { 
  3.         return false; 
  4.     } 
  5.  
  6.     $object_id = absint( $object_id ); 
  7.     if ( ! $object_id ) { 
  8.         return false; 
  9.     } 
  10.  
  11.     /** 
  12.      * Filters whether to retrieve metadata of a specific type. 
  13.      * 
  14.      * The dynamic portion of the hook, `$meta_type`, refers to the meta 
  15.      * object type (comment, post, or user). Returning a non-null value 
  16.      * will effectively short-circuit the function. 
  17.      * 
  18.      * @since 3.1.0 
  19.      * 
  20.      * @param null|array|string $value     The value get_metadata() should return - a single metadata value,  
  21.      *                                     or an array of values. 
  22.      * @param int               $object_id Object ID. 
  23.      * @param string            $meta_key  Meta key. 
  24.      * @param bool              $single    Whether to return only the first value of the specified $meta_key. 
  25.      */ 
  26.     $check = apply_filters( "get_{$meta_type}_metadata", null, $object_id, $meta_key, $single ); 
  27.     if ( null !== $check ) { 
  28.         if ( $single && is_array( $check ) ) 
  29.             return $check[0]; 
  30.         else 
  31.             return $check; 
  32.     } 
  33.  
  34.     $meta_cache = wp_cache_get($object_id, $meta_type . '_meta'); 
  35.  
  36.     if ( !$meta_cache ) { 
  37.         $meta_cache = update_meta_cache( $meta_type, array( $object_id ) ); 
  38.         $meta_cache = $meta_cache[$object_id]; 
  39.     } 
  40.  
  41.     if ( ! $meta_key ) { 
  42.         return $meta_cache; 
  43.     } 
  44.  
  45.     if ( isset($meta_cache[$meta_key]) ) { 
  46.         if ( $single ) 
  47.             return maybe_unserialize( $meta_cache[$meta_key][0] ); 
  48.         else 
  49.             return array_map('maybe_unserialize', $meta_cache[$meta_key]); 
  50.     } 
  51.  
  52.     if ($single) 
  53.         return ''; 
  54.     else 
  55.         return array(); 
  56. }