WordPress/wp-includes/meta.php
Boone Gorges 11226f02a8 Allow metadata to be deleted when meta_value matches 0 or '0'.
In `delete_metadata()`, be stricter about when to ignore a falsey value of
`$meta_value`.

For backward compatibility, an empty string for `$meta_value` is equivalent to
`null` or `false`.

Props sc0ttkclark.
Fixes #32224.
Built from https://develop.svn.wordpress.org/trunk@32331


git-svn-id: http://core.svn.wordpress.org/trunk@32302 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2015-05-01 16:38:29 +00:00

1671 lines
50 KiB
PHP

<?php
/**
* Metadata API
*
* Functions for retrieving and manipulating metadata of various WordPress object types. Metadata
* for an object is a represented by a simple key-value pair. Objects may contain multiple
* metadata entries that share the same key and differ only in their value.
*
* @package WordPress
* @subpackage Meta
* @since 2.9.0
*/
/**
* Add metadata for the specified object.
*
* @since 2.9.0
*
* @global wpdb $wpdb WordPress database abstraction object.
*
* @param string $meta_type Type of object metadata is for (e.g., comment, post, or user)
* @param int $object_id ID of the object metadata is for
* @param string $meta_key Metadata key
* @param mixed $meta_value Metadata value. Must be serializable if non-scalar.
* @param bool $unique Optional, default is false. Whether the specified metadata key should be
* unique for the object. If true, and the object already has a value for the specified
* metadata key, no change will be made
* @return int|bool The meta ID on success, false on failure.
*/
function add_metadata($meta_type, $object_id, $meta_key, $meta_value, $unique = false) {
global $wpdb;
if ( ! $meta_type || ! $meta_key || ! is_numeric( $object_id ) ) {
return false;
}
$object_id = absint( $object_id );
if ( ! $object_id ) {
return false;
}
$table = _get_meta_table( $meta_type );
if ( ! $table ) {
return false;
}
$column = sanitize_key($meta_type . '_id');
// expected_slashed ($meta_key)
$meta_key = wp_unslash($meta_key);
$meta_value = wp_unslash($meta_value);
$meta_value = sanitize_meta( $meta_key, $meta_value, $meta_type );
/**
* Filter whether to add metadata of a specific type.
*
* The dynamic portion of the hook, `$meta_type`, refers to the meta
* object type (comment, post, or user). Returning a non-null value
* will effectively short-circuit the function.
*
* @since 3.1.0
*
* @param null|bool $check Whether to allow adding metadata for the given type.
* @param int $object_id Object ID.
* @param string $meta_key Meta key.
* @param mixed $meta_value Meta value. Must be serializable if non-scalar.
* @param bool $unique Whether the specified meta key should be unique
* for the object. Optional. Default false.
*/
$check = apply_filters( "add_{$meta_type}_metadata", null, $object_id, $meta_key, $meta_value, $unique );
if ( null !== $check )
return $check;
if ( $unique && $wpdb->get_var( $wpdb->prepare(
"SELECT COUNT(*) FROM $table WHERE meta_key = %s AND $column = %d",
$meta_key, $object_id ) ) )
return false;
$_meta_value = $meta_value;
$meta_value = maybe_serialize( $meta_value );
/**
* Fires immediately before meta of a specific type is added.
*
* The dynamic portion of the hook, `$meta_type`, refers to the meta
* object type (comment, post, or user).
*
* @since 3.1.0
*
* @param int $object_id Object ID.
* @param string $meta_key Meta key.
* @param mixed $meta_value Meta value.
*/
do_action( "add_{$meta_type}_meta", $object_id, $meta_key, $_meta_value );
$result = $wpdb->insert( $table, array(
$column => $object_id,
'meta_key' => $meta_key,
'meta_value' => $meta_value
) );
if ( ! $result )
return false;
$mid = (int) $wpdb->insert_id;
wp_cache_delete($object_id, $meta_type . '_meta');
/**
* Fires immediately after meta of a specific type is added.
*
* The dynamic portion of the hook, `$meta_type`, refers to the meta
* object type (comment, post, or user).
*
* @since 2.9.0
*
* @param int $mid The meta ID after successful update.
* @param int $object_id Object ID.
* @param string $meta_key Meta key.
* @param mixed $meta_value Meta value.
*/
do_action( "added_{$meta_type}_meta", $mid, $object_id, $meta_key, $_meta_value );
return $mid;
}
/**
* Update metadata for the specified object. If no value already exists for the specified object
* ID and metadata key, the metadata will be added.
*
* @since 2.9.0
*
* @global wpdb $wpdb WordPress database abstraction object.
*
* @param string $meta_type Type of object metadata is for (e.g., comment, post, or user)
* @param int $object_id ID of the object metadata is for
* @param string $meta_key Metadata key
* @param mixed $meta_value Metadata value. Must be serializable if non-scalar.
* @param mixed $prev_value Optional. If specified, only update existing metadata entries with
* the specified value. Otherwise, update all entries.
* @return int|bool Meta ID if the key didn't exist, true on successful update, false on failure.
*/
function update_metadata($meta_type, $object_id, $meta_key, $meta_value, $prev_value = '') {
global $wpdb;
if ( ! $meta_type || ! $meta_key || ! is_numeric( $object_id ) ) {
return false;
}
$object_id = absint( $object_id );
if ( ! $object_id ) {
return false;
}
$table = _get_meta_table( $meta_type );
if ( ! $table ) {
return false;
}
$column = sanitize_key($meta_type . '_id');
$id_column = 'user' == $meta_type ? 'umeta_id' : 'meta_id';
// expected_slashed ($meta_key)
$meta_key = wp_unslash($meta_key);
$passed_value = $meta_value;
$meta_value = wp_unslash($meta_value);
$meta_value = sanitize_meta( $meta_key, $meta_value, $meta_type );
/**
* Filter whether to update metadata of a specific type.
*
* The dynamic portion of the hook, `$meta_type`, refers to the meta
* object type (comment, post, or user). Returning a non-null value
* will effectively short-circuit the function.
*
* @since 3.1.0
*
* @param null|bool $check Whether to allow updating metadata for the given type.
* @param int $object_id Object ID.
* @param string $meta_key Meta key.
* @param mixed $meta_value Meta value. Must be serializable if non-scalar.
* @param mixed $prev_value Optional. If specified, only update existing
* metadata entries with the specified value.
* Otherwise, update all entries.
*/
$check = apply_filters( "update_{$meta_type}_metadata", null, $object_id, $meta_key, $meta_value, $prev_value );
if ( null !== $check )
return (bool) $check;
// Compare existing value to new value if no prev value given and the key exists only once.
if ( empty($prev_value) ) {
$old_value = get_metadata($meta_type, $object_id, $meta_key);
if ( count($old_value) == 1 ) {
if ( $old_value[0] === $meta_value )
return false;
}
}
$meta_ids = $wpdb->get_col( $wpdb->prepare( "SELECT $id_column FROM $table WHERE meta_key = %s AND $column = %d", $meta_key, $object_id ) );
if ( empty( $meta_ids ) ) {
return add_metadata($meta_type, $object_id, $meta_key, $passed_value);
}
$_meta_value = $meta_value;
$meta_value = maybe_serialize( $meta_value );
$data = compact( 'meta_value' );
$where = array( $column => $object_id, 'meta_key' => $meta_key );
if ( !empty( $prev_value ) ) {
$prev_value = maybe_serialize($prev_value);
$where['meta_value'] = $prev_value;
}
foreach ( $meta_ids as $meta_id ) {
/**
* Fires immediately before updating metadata of a specific type.
*
* The dynamic portion of the hook, `$meta_type`, refers to the meta
* object type (comment, post, or user).
*
* @since 2.9.0
*
* @param int $meta_id ID of the metadata entry to update.
* @param int $object_id Object ID.
* @param string $meta_key Meta key.
* @param mixed $meta_value Meta value.
*/
do_action( "update_{$meta_type}_meta", $meta_id, $object_id, $meta_key, $_meta_value );
}
if ( 'post' == $meta_type ) {
foreach ( $meta_ids as $meta_id ) {
/**
* Fires immediately before updating a post's metadata.
*
* @since 2.9.0
*
* @param int $meta_id ID of metadata entry to update.
* @param int $object_id Object ID.
* @param string $meta_key Meta key.
* @param mixed $meta_value Meta value.
*/
do_action( 'update_postmeta', $meta_id, $object_id, $meta_key, $meta_value );
}
}
$result = $wpdb->update( $table, $data, $where );
if ( ! $result )
return false;
wp_cache_delete($object_id, $meta_type . '_meta');
foreach ( $meta_ids as $meta_id ) {
/**
* Fires immediately after updating metadata of a specific type.
*
* The dynamic portion of the hook, `$meta_type`, refers to the meta
* object type (comment, post, or user).
*
* @since 2.9.0
*
* @param int $meta_id ID of updated metadata entry.
* @param int $object_id Object ID.
* @param string $meta_key Meta key.
* @param mixed $meta_value Meta value.
*/
do_action( "updated_{$meta_type}_meta", $meta_id, $object_id, $meta_key, $_meta_value );
}
if ( 'post' == $meta_type ) {
foreach ( $meta_ids as $meta_id ) {
/**
* Fires immediately after updating a post's metadata.
*
* @since 2.9.0
*
* @param int $meta_id ID of updated metadata entry.
* @param int $object_id Object ID.
* @param string $meta_key Meta key.
* @param mixed $meta_value Meta value.
*/
do_action( 'updated_postmeta', $meta_id, $object_id, $meta_key, $meta_value );
}
}
return true;
}
/**
* Delete metadata for the specified object.
*
* @since 2.9.0
*
* @global wpdb $wpdb WordPress database abstraction object.
*
* @param string $meta_type Type of object metadata is for (e.g., comment, post, or user)
* @param int $object_id ID of the object metadata is for
* @param string $meta_key Metadata key
* @param mixed $meta_value Optional. Metadata value. Must be serializable if non-scalar. If specified, only delete
* metadata entries with this value. Otherwise, delete all entries with the specified meta_key.
* Pass `null, `false`, or an empty string to skip this check. (For backward compatibility,
* it is not possible to pass an empty string to delete those entries with an empty string
* for a value.)
* @param bool $delete_all Optional, default is false. If true, delete matching metadata entries for all objects,
* ignoring the specified object_id. Otherwise, only delete matching metadata entries for
* the specified object_id.
* @return bool True on successful delete, false on failure.
*/
function delete_metadata($meta_type, $object_id, $meta_key, $meta_value = '', $delete_all = false) {
global $wpdb;
if ( ! $meta_type || ! $meta_key || ! is_numeric( $object_id ) && ! $delete_all ) {
return false;
}
$object_id = absint( $object_id );
if ( ! $object_id && ! $delete_all ) {
return false;
}
$table = _get_meta_table( $meta_type );
if ( ! $table ) {
return false;
}
$type_column = sanitize_key($meta_type . '_id');
$id_column = 'user' == $meta_type ? 'umeta_id' : 'meta_id';
// expected_slashed ($meta_key)
$meta_key = wp_unslash($meta_key);
$meta_value = wp_unslash($meta_value);
/**
* Filter whether to delete metadata of a specific type.
*
* The dynamic portion of the hook, `$meta_type`, refers to the meta
* object type (comment, post, or user). Returning a non-null value
* will effectively short-circuit the function.
*
* @since 3.1.0
*
* @param null|bool $delete Whether to allow metadata deletion of the given type.
* @param int $object_id Object ID.
* @param string $meta_key Meta key.
* @param mixed $meta_value Meta value. Must be serializable if non-scalar.
* @param bool $delete_all Whether to delete the matching metadata entries
* for all objects, ignoring the specified $object_id.
* Default false.
*/
$check = apply_filters( "delete_{$meta_type}_metadata", null, $object_id, $meta_key, $meta_value, $delete_all );
if ( null !== $check )
return (bool) $check;
$_meta_value = $meta_value;
$meta_value = maybe_serialize( $meta_value );
$query = $wpdb->prepare( "SELECT $id_column FROM $table WHERE meta_key = %s", $meta_key );
if ( !$delete_all )
$query .= $wpdb->prepare(" AND $type_column = %d", $object_id );
if ( '' !== $meta_value && null !== $meta_value && false !== $meta_value )
$query .= $wpdb->prepare(" AND meta_value = %s", $meta_value );
$meta_ids = $wpdb->get_col( $query );
if ( !count( $meta_ids ) )
return false;
if ( $delete_all )
$object_ids = $wpdb->get_col( $wpdb->prepare( "SELECT $type_column FROM $table WHERE meta_key = %s", $meta_key ) );
/**
* Fires immediately before deleting metadata of a specific type.
*
* The dynamic portion of the hook, `$meta_type`, refers to the meta
* object type (comment, post, or user).
*
* @since 3.1.0
*
* @param array $meta_ids An array of metadata entry IDs to delete.
* @param int $object_id Object ID.
* @param string $meta_key Meta key.
* @param mixed $meta_value Meta value.
*/
do_action( "delete_{$meta_type}_meta", $meta_ids, $object_id, $meta_key, $_meta_value );
// Old-style action.
if ( 'post' == $meta_type ) {
/**
* Fires immediately before deleting metadata for a post.
*
* @since 2.9.0
*
* @param array $meta_ids An array of post metadata entry IDs to delete.
*/
do_action( 'delete_postmeta', $meta_ids );
}
$query = "DELETE FROM $table WHERE $id_column IN( " . implode( ',', $meta_ids ) . " )";
$count = $wpdb->query($query);
if ( !$count )
return false;
if ( $delete_all ) {
foreach ( (array) $object_ids as $o_id ) {
wp_cache_delete($o_id, $meta_type . '_meta');
}
} else {
wp_cache_delete($object_id, $meta_type . '_meta');
}
/**
* Fires immediately after deleting metadata of a specific type.
*
* The dynamic portion of the hook name, `$meta_type`, refers to the meta
* object type (comment, post, or user).
*
* @since 2.9.0
*
* @param array $meta_ids An array of deleted metadata entry IDs.
* @param int $object_id Object ID.
* @param string $meta_key Meta key.
* @param mixed $meta_value Meta value.
*/
do_action( "deleted_{$meta_type}_meta", $meta_ids, $object_id, $meta_key, $_meta_value );
// Old-style action.
if ( 'post' == $meta_type ) {
/**
* Fires immediately after deleting metadata for a post.
*
* @since 2.9.0
*
* @param array $meta_ids An array of deleted post metadata entry IDs.
*/
do_action( 'deleted_postmeta', $meta_ids );
}
return true;
}
/**
* Retrieve metadata for the specified object.
*
* @since 2.9.0
*
* @param string $meta_type Type of object metadata is for (e.g., comment, post, or user)
* @param int $object_id ID of the object metadata is for
* @param string $meta_key Optional. Metadata key. If not specified, retrieve all metadata for
* the specified object.
* @param bool $single Optional, default is false. If true, return only the first value of the
* specified meta_key. This parameter has no effect if meta_key is not specified.
* @return mixed Single metadata value, or array of values
*/
function get_metadata($meta_type, $object_id, $meta_key = '', $single = false) {
if ( ! $meta_type || ! is_numeric( $object_id ) ) {
return false;
}
$object_id = absint( $object_id );
if ( ! $object_id ) {
return false;
}
/**
* Filter whether to retrieve metadata of a specific type.
*
* The dynamic portion of the hook, `$meta_type`, refers to the meta
* object type (comment, post, or user). Returning a non-null value
* will effectively short-circuit the function.
*
* @since 3.1.0
*
* @param null|array|string $value The value get_metadata() should
* return - a single metadata value,
* or an array of values.
* @param int $object_id Object ID.
* @param string $meta_key Meta key.
* @param string|array $single Meta value, or an array of values.
*/
$check = apply_filters( "get_{$meta_type}_metadata", null, $object_id, $meta_key, $single );
if ( null !== $check ) {
if ( $single && is_array( $check ) )
return $check[0];
else
return $check;
}
$meta_cache = wp_cache_get($object_id, $meta_type . '_meta');
if ( !$meta_cache ) {
$meta_cache = update_meta_cache( $meta_type, array( $object_id ) );
$meta_cache = $meta_cache[$object_id];
}
if ( ! $meta_key ) {
return $meta_cache;
}
if ( isset($meta_cache[$meta_key]) ) {
if ( $single )
return maybe_unserialize( $meta_cache[$meta_key][0] );
else
return array_map('maybe_unserialize', $meta_cache[$meta_key]);
}
if ($single)
return '';
else
return array();
}
/**
* Determine if a meta key is set for a given object
*
* @since 3.3.0
*
* @param string $meta_type Type of object metadata is for (e.g., comment, post, or user)
* @param int $object_id ID of the object metadata is for
* @param string $meta_key Metadata key.
* @return boolean true of the key is set, false if not.
*/
function metadata_exists( $meta_type, $object_id, $meta_key ) {
if ( ! $meta_type || ! is_numeric( $object_id ) ) {
return false;
}
$object_id = absint( $object_id );
if ( ! $object_id ) {
return false;
}
/** This filter is documented in wp-includes/meta.php */
$check = apply_filters( "get_{$meta_type}_metadata", null, $object_id, $meta_key, true );
if ( null !== $check )
return (bool) $check;
$meta_cache = wp_cache_get( $object_id, $meta_type . '_meta' );
if ( !$meta_cache ) {
$meta_cache = update_meta_cache( $meta_type, array( $object_id ) );
$meta_cache = $meta_cache[$object_id];
}
if ( isset( $meta_cache[ $meta_key ] ) )
return true;
return false;
}
/**
* Get meta data by meta ID
*
* @since 3.3.0
*
* @param string $meta_type Type of object metadata is for (e.g., comment, post, or user)
* @param int $meta_id ID for a specific meta row
* @return object Meta object or false.
*/
function get_metadata_by_mid( $meta_type, $meta_id ) {
global $wpdb;
if ( ! $meta_type || ! is_numeric( $meta_id ) ) {
return false;
}
$meta_id = absint( $meta_id );
if ( ! $meta_id ) {
return false;
}
$table = _get_meta_table( $meta_type );
if ( ! $table ) {
return false;
}
$id_column = ( 'user' == $meta_type ) ? 'umeta_id' : 'meta_id';
$meta = $wpdb->get_row( $wpdb->prepare( "SELECT * FROM $table WHERE $id_column = %d", $meta_id ) );
if ( empty( $meta ) )
return false;
if ( isset( $meta->meta_value ) )
$meta->meta_value = maybe_unserialize( $meta->meta_value );
return $meta;
}
/**
* Update meta data by meta ID
*
* @since 3.3.0
*
* @param string $meta_type Type of object metadata is for (e.g., comment, post, or user)
* @param int $meta_id ID for a specific meta row
* @param string $meta_value Metadata value
* @param string $meta_key Optional, you can provide a meta key to update it
* @return bool True on successful update, false on failure.
*/
function update_metadata_by_mid( $meta_type, $meta_id, $meta_value, $meta_key = false ) {
global $wpdb;
// Make sure everything is valid.
if ( ! $meta_type || ! is_numeric( $meta_id ) ) {
return false;
}
$meta_id = absint( $meta_id );
if ( ! $meta_id ) {
return false;
}
$table = _get_meta_table( $meta_type );
if ( ! $table ) {
return false;
}
$column = sanitize_key($meta_type . '_id');
$id_column = 'user' == $meta_type ? 'umeta_id' : 'meta_id';
// Fetch the meta and go on if it's found.
if ( $meta = get_metadata_by_mid( $meta_type, $meta_id ) ) {
$original_key = $meta->meta_key;
$object_id = $meta->{$column};
// If a new meta_key (last parameter) was specified, change the meta key,
// otherwise use the original key in the update statement.
if ( false === $meta_key ) {
$meta_key = $original_key;
} elseif ( ! is_string( $meta_key ) ) {
return false;
}
// Sanitize the meta
$_meta_value = $meta_value;
$meta_value = sanitize_meta( $meta_key, $meta_value, $meta_type );
$meta_value = maybe_serialize( $meta_value );
// Format the data query arguments.
$data = array(
'meta_key' => $meta_key,
'meta_value' => $meta_value
);
// Format the where query arguments.
$where = array();
$where[$id_column] = $meta_id;
/** This action is documented in wp-includes/meta.php */
do_action( "update_{$meta_type}_meta", $meta_id, $object_id, $meta_key, $_meta_value );
if ( 'post' == $meta_type ) {
/** This action is documented in wp-includes/meta.php */
do_action( 'update_postmeta', $meta_id, $object_id, $meta_key, $meta_value );
}
// Run the update query, all fields in $data are %s, $where is a %d.
$result = $wpdb->update( $table, $data, $where, '%s', '%d' );
if ( ! $result )
return false;
// Clear the caches.
wp_cache_delete($object_id, $meta_type . '_meta');
/** This action is documented in wp-includes/meta.php */
do_action( "updated_{$meta_type}_meta", $meta_id, $object_id, $meta_key, $_meta_value );
if ( 'post' == $meta_type ) {
/** This action is documented in wp-includes/meta.php */
do_action( 'updated_postmeta', $meta_id, $object_id, $meta_key, $meta_value );
}
return true;
}
// And if the meta was not found.
return false;
}
/**
* Delete meta data by meta ID
*
* @since 3.3.0
*
* @param string $meta_type Type of object metadata is for (e.g., comment, post, or user)
* @param int $meta_id ID for a specific meta row
* @return bool True on successful delete, false on failure.
*/
function delete_metadata_by_mid( $meta_type, $meta_id ) {
global $wpdb;
// Make sure everything is valid.
if ( ! $meta_type || ! is_numeric( $meta_id ) ) {
return false;
}
$meta_id = absint( $meta_id );
if ( ! $meta_id ) {
return false;
}
$table = _get_meta_table( $meta_type );
if ( ! $table ) {
return false;
}
// object and id columns
$column = sanitize_key($meta_type . '_id');
$id_column = 'user' == $meta_type ? 'umeta_id' : 'meta_id';
// Fetch the meta and go on if it's found.
if ( $meta = get_metadata_by_mid( $meta_type, $meta_id ) ) {
$object_id = $meta->{$column};
/** This action is documented in wp-includes/meta.php */
do_action( "delete_{$meta_type}_meta", (array) $meta_id, $object_id, $meta->meta_key, $meta->meta_value );
// Old-style action.
if ( 'post' == $meta_type || 'comment' == $meta_type ) {
/**
* Fires immediately before deleting post or comment metadata of a specific type.
*
* The dynamic portion of the hook, `$meta_type`, refers to the meta
* object type (post or comment).
*
* @since 3.4.0
*
* @param int $meta_id ID of the metadata entry to delete.
*/
do_action( "delete_{$meta_type}meta", $meta_id );
}
// Run the query, will return true if deleted, false otherwise
$result = (bool) $wpdb->delete( $table, array( $id_column => $meta_id ) );
// Clear the caches.
wp_cache_delete($object_id, $meta_type . '_meta');
/** This action is documented in wp-includes/meta.php */
do_action( "deleted_{$meta_type}_meta", (array) $meta_id, $object_id, $meta->meta_key, $meta->meta_value );
// Old-style action.
if ( 'post' == $meta_type || 'comment' == $meta_type ) {
/**
* Fires immediately after deleting post or comment metadata of a specific type.
*
* The dynamic portion of the hook, `$meta_type`, refers to the meta
* object type (post or comment).
*
* @since 3.4.0
*
* @param int $meta_ids Deleted metadata entry ID.
*/
do_action( "deleted_{$meta_type}meta", $meta_id );
}
return $result;
}
// Meta id was not found.
return false;
}
/**
* Update the metadata cache for the specified objects.
*
* @since 2.9.0
*
* @global wpdb $wpdb WordPress database abstraction object.
*
* @param string $meta_type Type of object metadata is for (e.g., comment, post, or user)
* @param int|array $object_ids array or comma delimited list of object IDs to update cache for
* @return mixed Metadata cache for the specified objects, or false on failure.
*/
function update_meta_cache($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;
}
/**
* Given a meta query, generates SQL clauses to be appended to a main query.
*
* @since 3.2.0
*
* @see WP_Meta_Query
*
* @param array $meta_query A meta query.
* @param string $type Type of meta.
* @param string $primary_table Primary database table name.
* @param string $primary_id_column Primary ID column name.
* @param object $context Optional. The main query object
* @return array Associative array of `JOIN` and `WHERE` SQL.
*/
function get_meta_sql( $meta_query, $type, $primary_table, $primary_id_column, $context = null ) {
$meta_query_obj = new WP_Meta_Query( $meta_query );
return $meta_query_obj->get_sql( $type, $primary_table, $primary_id_column, $context );
}
/**
* Class for generating SQL clauses that filter a primary query according to metadata keys and values.
*
* `WP_Meta_Query` is a helper that allows primary query classes, such as {@see WP_Query} and {@see WP_User_Query},
* to filter their results by object metadata, by generating `JOIN` and `WHERE` subclauses to be attached
* to the primary SQL query string.
*
* @since 3.2.0
*/
class WP_Meta_Query {
/**
* Array of metadata queries.
*
* See {@see WP_Meta_Query::__construct()} for information on meta query arguments.
*
* @since 3.2.0
* @access public
* @var array
*/
public $queries = array();
/**
* The relation between the queries. Can be one of 'AND' or 'OR'.
*
* @since 3.2.0
* @access public
* @var string
*/
public $relation;
/**
* Database table to query for the metadata.
*
* @since 4.1.0
* @access public
* @var string
*/
public $meta_table;
/**
* Column in meta_table that represents the ID of the object the metadata belongs to.
*
* @since 4.1.0
* @access public
* @var string
*/
public $meta_id_column;
/**
* Database table that where the metadata's objects are stored (eg $wpdb->users).
*
* @since 4.1.0
* @access public
* @var string
*/
public $primary_table;
/**
* Column in primary_table that represents the ID of the object.
*
* @since 4.1.0
* @access public
* @var string
*/
public $primary_id_column;
/**
* A flat list of table aliases used in JOIN clauses.
*
* @since 4.1.0
* @access protected
* @var array
*/
protected $table_aliases = array();
/**
* A flat list of clauses, keyed by clause 'name'.
*
* @since 4.2.0
* @access protected
* @var array
*/
protected $clauses = array();
/**
* Constructor.
*
* @since 3.2.0
* @since 4.2.0 Introduced support for naming query clauses by associative array keys.
*
* @access public
*
* @param array $meta_query {
* Array of meta query clauses. When first-order clauses use strings as their array keys, they may be
* referenced in the 'orderby' parameter of the parent query.
*
* @type string $relation Optional. The MySQL keyword used to join
* the clauses of the query. Accepts 'AND', or 'OR'. Default 'AND'.
* @type array {
* Optional. An array of first-order clause parameters, or another fully-formed meta query.
*
* @type string $key Meta key to filter by.
* @type string $value Meta value to filter by.
* @type string $compare MySQL operator used for comparing the $value. Accepts '=',
* '!=', '>', '>=', '<', '<=', 'LIKE', 'NOT LIKE', 'IN', 'NOT IN',
* 'BETWEEN', 'NOT BETWEEN', 'REGEXP', 'NOT REGEXP', or 'RLIKE'.
* Default is 'IN' when `$value` is an array, '=' otherwise.
* @type string $type MySQL data type that the meta_value column will be CAST to for
* comparisons. Accepts 'NUMERIC', 'BINARY', 'CHAR', 'DATE',
* 'DATETIME', 'DECIMAL', 'SIGNED', 'TIME', or 'UNSIGNED'.
* Default is 'CHAR'.
* }
* }
*/
public function __construct( $meta_query = false ) {
if ( !$meta_query )
return;
if ( isset( $meta_query['relation'] ) && strtoupper( $meta_query['relation'] ) == 'OR' ) {
$this->relation = 'OR';
} else {
$this->relation = 'AND';
}
$this->queries = $this->sanitize_query( $meta_query );
}
/**
* Ensure the 'meta_query' argument passed to the class constructor is well-formed.
*
* Eliminates empty items and ensures that a 'relation' is set.
*
* @since 4.1.0
* @access public
*
* @param array $queries Array of query clauses.
* @return array Sanitized array of query clauses.
*/
public function sanitize_query( $queries ) {
$clean_queries = array();
if ( ! is_array( $queries ) ) {
return $clean_queries;
}
foreach ( $queries as $key => $query ) {
if ( 'relation' === $key ) {
$relation = $query;
} elseif ( ! is_array( $query ) ) {
continue;
// First-order clause.
} elseif ( $this->is_first_order_clause( $query ) ) {
if ( isset( $query['value'] ) && array() === $query['value'] ) {
unset( $query['value'] );
}
$clean_queries[ $key ] = $query;
// Otherwise, it's a nested query, so we recurse.
} else {
$cleaned_query = $this->sanitize_query( $query );
if ( ! empty( $cleaned_query ) ) {
$clean_queries[ $key ] = $cleaned_query;
}
}
}
if ( empty( $clean_queries ) ) {
return $clean_queries;
}
// Sanitize the 'relation' key provided in the query.
if ( isset( $relation ) && 'OR' === strtoupper( $relation ) ) {
$clean_queries['relation'] = 'OR';
/*
* If there is only a single clause, call the relation 'OR'.
* This value will not actually be used to join clauses, but it
* simplifies the logic around combining key-only queries.
*/
} elseif ( 1 === count( $clean_queries ) ) {
$clean_queries['relation'] = 'OR';
// Default to AND.
} else {
$clean_queries['relation'] = 'AND';
}
return $clean_queries;
}
/**
* Determine whether a query clause is first-order.
*
* A first-order meta query clause is one that has either a 'key' or
* a 'value' array key.
*
* @since 4.1.0
* @access protected
*
* @param array $query Meta query arguments.
* @return bool Whether the query clause is a first-order clause.
*/
protected function is_first_order_clause( $query ) {
return isset( $query['key'] ) || isset( $query['value'] );
}
/**
* Constructs a meta query based on 'meta_*' query vars
*
* @since 3.2.0
* @access public
*
* @param array $qv The query variables
*/
public function parse_query_vars( $qv ) {
$meta_query = array();
/*
* For orderby=meta_value to work correctly, simple query needs to be
* first (so that its table join is against an unaliased meta table) and
* needs to be its own clause (so it doesn't interfere with the logic of
* the rest of the meta_query).
*/
$primary_meta_query = array();
foreach ( array( 'key', 'compare', 'type' ) as $key ) {
if ( ! empty( $qv[ "meta_$key" ] ) ) {
$primary_meta_query[ $key ] = $qv[ "meta_$key" ];
}
}
// WP_Query sets 'meta_value' = '' by default.
if ( isset( $qv['meta_value'] ) && '' !== $qv['meta_value'] && ( ! is_array( $qv['meta_value'] ) || $qv['meta_value'] ) ) {
$primary_meta_query['value'] = $qv['meta_value'];
}
$existing_meta_query = isset( $qv['meta_query'] ) && is_array( $qv['meta_query'] ) ? $qv['meta_query'] : array();
if ( ! empty( $primary_meta_query ) && ! empty( $existing_meta_query ) ) {
$meta_query = array(
'relation' => 'AND',
$primary_meta_query,
$existing_meta_query,
);
} elseif ( ! empty( $primary_meta_query ) ) {
$meta_query = array(
$primary_meta_query,
);
} elseif ( ! empty( $existing_meta_query ) ) {
$meta_query = $existing_meta_query;
}
$this->__construct( $meta_query );
}
/**
* Return the appropriate alias for the given meta type if applicable.
*
* @since 3.7.0
* @access public
*
* @param string $type MySQL type to cast meta_value.
* @return string MySQL type.
*/
public function get_cast_for_type( $type = '' ) {
if ( empty( $type ) )
return 'CHAR';
$meta_type = strtoupper( $type );
if ( ! preg_match( '/^(?:BINARY|CHAR|DATE|DATETIME|SIGNED|UNSIGNED|TIME|NUMERIC(?:\(\d+(?:,\s?\d+)?\))?|DECIMAL(?:\(\d+(?:,\s?\d+)?\))?)$/', $meta_type ) )
return 'CHAR';
if ( 'NUMERIC' == $meta_type )
$meta_type = 'SIGNED';
return $meta_type;
}
/**
* Generates SQL clauses to be appended to a main query.
*
* @since 3.2.0
* @access public
*
* @param string $type Type of meta, eg 'user', 'post'.
* @param string $primary_table Database table where the object being filtered is stored (eg wp_users).
* @param string $primary_id_column ID column for the filtered object in $primary_table.
* @param object $context Optional. The main query object.
* @return array {
* Array containing JOIN and WHERE SQL clauses to append to the main query.
*
* @type string $join SQL fragment to append to the main JOIN clause.
* @type string $where SQL fragment to append to the main WHERE clause.
* }
*/
public function get_sql( $type, $primary_table, $primary_id_column, $context = null ) {
if ( ! $meta_table = _get_meta_table( $type ) ) {
return false;
}
$this->meta_table = $meta_table;
$this->meta_id_column = sanitize_key( $type . '_id' );
$this->primary_table = $primary_table;
$this->primary_id_column = $primary_id_column;
$sql = $this->get_sql_clauses();
/*
* If any JOINs are LEFT JOINs (as in the case of NOT EXISTS), then all JOINs should
* be LEFT. Otherwise posts with no metadata will be excluded from results.
*/
if ( false !== strpos( $sql['join'], 'LEFT JOIN' ) ) {
$sql['join'] = str_replace( 'INNER JOIN', 'LEFT JOIN', $sql['join'] );
}
/**
* Filter the meta query's generated SQL.
*
* @since 3.1.0
*
* @param array $args {
* An array of meta query SQL arguments.
*
* @type array $clauses Array containing the query's JOIN and WHERE clauses.
* @type array $queries Array of meta queries.
* @type string $type Type of meta.
* @type string $primary_table Primary table.
* @type string $primary_id_column Primary column ID.
* @type object $context The main query object.
* }
*/
return apply_filters_ref_array( 'get_meta_sql', array( $sql, $this->queries, $type, $primary_table, $primary_id_column, $context ) );
}
/**
* Generate SQL clauses to be appended to a main query.
*
* Called by the public {@see WP_Meta_Query::get_sql()}, this method
* is abstracted out to maintain parity with the other Query classes.
*
* @since 4.1.0
* @access protected
*
* @return array {
* Array containing JOIN and WHERE SQL clauses to append to the main query.
*
* @type string $join SQL fragment to append to the main JOIN clause.
* @type string $where SQL fragment to append to the main WHERE clause.
* }
*/
protected function get_sql_clauses() {
/*
* $queries are passed by reference to get_sql_for_query() for recursion.
* To keep $this->queries unaltered, pass a copy.
*/
$queries = $this->queries;
$sql = $this->get_sql_for_query( $queries );
if ( ! empty( $sql['where'] ) ) {
$sql['where'] = ' AND ' . $sql['where'];
}
return $sql;
}
/**
* Generate SQL clauses for a single query array.
*
* If nested subqueries are found, this method recurses the tree to
* produce the properly nested SQL.
*
* @since 4.1.0
* @access protected
*
* @param array $query Query to parse, passed by reference.
* @param int $depth Optional. Number of tree levels deep we currently are.
* Used to calculate indentation. Default 0.
* @return array {
* Array containing JOIN and WHERE SQL clauses to append to a single query array.
*
* @type string $join SQL fragment to append to the main JOIN clause.
* @type string $where SQL fragment to append to the main WHERE clause.
* }
*/
protected function get_sql_for_query( &$query, $depth = 0 ) {
$sql_chunks = array(
'join' => array(),
'where' => array(),
);
$sql = array(
'join' => '',
'where' => '',
);
$indent = '';
for ( $i = 0; $i < $depth; $i++ ) {
$indent .= " ";
}
foreach ( $query as $key => &$clause ) {
if ( 'relation' === $key ) {
$relation = $query['relation'];
} elseif ( is_array( $clause ) ) {
// This is a first-order clause.
if ( $this->is_first_order_clause( $clause ) ) {
$clause_sql = $this->get_sql_for_clause( $clause, $query, $key );
$where_count = count( $clause_sql['where'] );
if ( ! $where_count ) {
$sql_chunks['where'][] = '';
} elseif ( 1 === $where_count ) {
$sql_chunks['where'][] = $clause_sql['where'][0];
} else {
$sql_chunks['where'][] = '( ' . implode( ' AND ', $clause_sql['where'] ) . ' )';
}
$sql_chunks['join'] = array_merge( $sql_chunks['join'], $clause_sql['join'] );
// This is a subquery, so we recurse.
} else {
$clause_sql = $this->get_sql_for_query( $clause, $depth + 1 );
$sql_chunks['where'][] = $clause_sql['where'];
$sql_chunks['join'][] = $clause_sql['join'];
}
}
}
// Filter to remove empties.
$sql_chunks['join'] = array_filter( $sql_chunks['join'] );
$sql_chunks['where'] = array_filter( $sql_chunks['where'] );
if ( empty( $relation ) ) {
$relation = 'AND';
}
// Filter duplicate JOIN clauses and combine into a single string.
if ( ! empty( $sql_chunks['join'] ) ) {
$sql['join'] = implode( ' ', array_unique( $sql_chunks['join'] ) );
}
// Generate a single WHERE clause with proper brackets and indentation.
if ( ! empty( $sql_chunks['where'] ) ) {
$sql['where'] = '( ' . "\n " . $indent . implode( ' ' . "\n " . $indent . $relation . ' ' . "\n " . $indent, $sql_chunks['where'] ) . "\n" . $indent . ')';
}
return $sql;
}
/**
* Generate SQL JOIN and WHERE clauses for a first-order query clause.
*
* "First-order" means that it's an array with a 'key' or 'value'.
*
* @since 4.1.0
* @access public
*
* @param array $clause Query clause, passed by reference.
* @param array $parent_query Parent query array.
* @param string $clause_key Optional. The array key used to name the clause in the original `$meta_query`
* parameters. If not provided, a key will be generated automatically.
* @return array {
* Array containing JOIN and WHERE SQL clauses to append to a first-order query.
*
* @type string $join SQL fragment to append to the main JOIN clause.
* @type string $where SQL fragment to append to the main WHERE clause.
* }
*/
public function get_sql_for_clause( &$clause, $parent_query, $clause_key = '' ) {
global $wpdb;
$sql_chunks = array(
'where' => array(),
'join' => array(),
);
if ( isset( $clause['compare'] ) ) {
$clause['compare'] = strtoupper( $clause['compare'] );
} else {
$clause['compare'] = isset( $clause['value'] ) && is_array( $clause['value'] ) ? 'IN' : '=';
}
if ( ! in_array( $clause['compare'], array(
'=', '!=', '>', '>=', '<', '<=',
'LIKE', 'NOT LIKE',
'IN', 'NOT IN',
'BETWEEN', 'NOT BETWEEN',
'EXISTS', 'NOT EXISTS',
'REGEXP', 'NOT REGEXP', 'RLIKE'
) ) ) {
$clause['compare'] = '=';
}
$meta_compare = $clause['compare'];
// First build the JOIN clause, if one is required.
$join = '';
// We prefer to avoid joins if possible. Look for an existing join compatible with this clause.
$alias = $this->find_compatible_table_alias( $clause, $parent_query );
if ( false === $alias ) {
$i = count( $this->table_aliases );
$alias = $i ? 'mt' . $i : $this->meta_table;
// JOIN clauses for NOT EXISTS have their own syntax.
if ( 'NOT EXISTS' === $meta_compare ) {
$join .= " LEFT JOIN $this->meta_table";
$join .= $i ? " AS $alias" : '';
$join .= $wpdb->prepare( " ON ($this->primary_table.$this->primary_id_column = $alias.$this->meta_id_column AND $alias.meta_key = %s )", $clause['key'] );
// All other JOIN clauses.
} else {
$join .= " INNER JOIN $this->meta_table";
$join .= $i ? " AS $alias" : '';
$join .= " ON ( $this->primary_table.$this->primary_id_column = $alias.$this->meta_id_column )";
}
$this->table_aliases[] = $alias;
$sql_chunks['join'][] = $join;
}
// Save the alias to this clause, for future siblings to find.
$clause['alias'] = $alias;
// Determine the data type.
$_meta_type = isset( $clause['type'] ) ? $clause['type'] : '';
$meta_type = $this->get_cast_for_type( $_meta_type );
$clause['cast'] = $meta_type;
// Fallback for clause keys is the table alias.
if ( ! $clause_key ) {
$clause_key = $clause['alias'];
}
// Ensure unique clause keys, so none are overwritten.
$iterator = 1;
$clause_key_base = $clause_key;
while ( isset( $this->clauses[ $clause_key ] ) ) {
$clause_key = $clause_key_base . '-' . $iterator;
$iterator++;
}
// Store the clause in our flat array.
$this->clauses[ $clause_key ] =& $clause;
// Next, build the WHERE clause.
// meta_key.
if ( array_key_exists( 'key', $clause ) ) {
if ( 'NOT EXISTS' === $meta_compare ) {
$sql_chunks['where'][] = $alias . '.' . $this->meta_id_column . ' IS NULL';
} else {
$sql_chunks['where'][] = $wpdb->prepare( "$alias.meta_key = %s", trim( $clause['key'] ) );
}
}
// meta_value.
if ( array_key_exists( 'value', $clause ) ) {
$meta_value = $clause['value'];
if ( in_array( $meta_compare, array( 'IN', 'NOT IN', 'BETWEEN', 'NOT BETWEEN' ) ) ) {
if ( ! is_array( $meta_value ) ) {
$meta_value = preg_split( '/[,\s]+/', $meta_value );
}
} else {
$meta_value = trim( $meta_value );
}
switch ( $meta_compare ) {
case 'IN' :
case 'NOT IN' :
$meta_compare_string = '(' . substr( str_repeat( ',%s', count( $meta_value ) ), 1 ) . ')';
$where = $wpdb->prepare( $meta_compare_string, $meta_value );
break;
case 'BETWEEN' :
case 'NOT BETWEEN' :
$meta_value = array_slice( $meta_value, 0, 2 );
$where = $wpdb->prepare( '%s AND %s', $meta_value );
break;
case 'LIKE' :
case 'NOT LIKE' :
$meta_value = '%' . $wpdb->esc_like( $meta_value ) . '%';
$where = $wpdb->prepare( '%s', $meta_value );
break;
// EXISTS with a value is interpreted as '='.
case 'EXISTS' :
$meta_compare = '=';
$where = $wpdb->prepare( '%s', $meta_value );
break;
// 'value' is ignored for NOT EXISTS.
case 'NOT EXISTS' :
$where = '';
break;
default :
$where = $wpdb->prepare( '%s', $meta_value );
break;
}
if ( $where ) {
$sql_chunks['where'][] = "CAST($alias.meta_value AS {$meta_type}) {$meta_compare} {$where}";
}
}
/*
* Multiple WHERE clauses (for meta_key and meta_value) should
* be joined in parentheses.
*/
if ( 1 < count( $sql_chunks['where'] ) ) {
$sql_chunks['where'] = array( '( ' . implode( ' AND ', $sql_chunks['where'] ) . ' )' );
}
return $sql_chunks;
}
/**
* Get a flattened list of sanitized meta clauses.
*
* This array should be used for clause lookup, as when the table alias and CAST type must be determined for
* a value of 'orderby' corresponding to a meta clause.
*
* @since 4.2.0
* @access public
*
* @return array Meta clauses.
*/
public function get_clauses() {
return $this->clauses;
}
/**
* Identify an existing table alias that is compatible with the current
* query clause.
*
* We avoid unnecessary table joins by allowing each clause to look for
* an existing table alias that is compatible with the query that it
* needs to perform.
*
* An existing alias is compatible if (a) it is a sibling of `$clause`
* (ie, it's under the scope of the same relation), and (b) the combination
* of operator and relation between the clauses allows for a shared table join.
* In the case of {@see WP_Meta_Query}, this only applies to 'IN' clauses that
* are connected by the relation 'OR'.
*
* @since 4.1.0
* @access protected
*
* @param array $clause Query clause.
* @param array $parent_query Parent query of $clause.
* @return string|bool Table alias if found, otherwise false.
*/
protected function find_compatible_table_alias( $clause, $parent_query ) {
$alias = false;
foreach ( $parent_query as $sibling ) {
// If the sibling has no alias yet, there's nothing to check.
if ( empty( $sibling['alias'] ) ) {
continue;
}
// We're only interested in siblings that are first-order clauses.
if ( ! is_array( $sibling ) || ! $this->is_first_order_clause( $sibling ) ) {
continue;
}
$compatible_compares = array();
// Clauses connected by OR can share joins as long as they have "positive" operators.
if ( 'OR' === $parent_query['relation'] ) {
$compatible_compares = array( '=', 'IN', 'BETWEEN', 'LIKE', 'REGEXP', 'RLIKE', '>', '>=', '<', '<=' );
// Clauses joined by AND with "negative" operators share a join only if they also share a key.
} elseif ( isset( $sibling['key'] ) && isset( $clause['key'] ) && $sibling['key'] === $clause['key'] ) {
$compatible_compares = array( '!=', 'NOT IN', 'NOT LIKE' );
}
$clause_compare = strtoupper( $clause['compare'] );
$sibling_compare = strtoupper( $sibling['compare'] );
if ( in_array( $clause_compare, $compatible_compares ) && in_array( $sibling_compare, $compatible_compares ) ) {
$alias = $sibling['alias'];
break;
}
}
/**
* Filter the table alias identified as compatible with the current clause.
*
* @since 4.1.0
*
* @param string|bool $alias Table alias, or false if none was found.
* @param array $clause First-order query clause.
* @param array $parent_query Parent of $clause.
* @param object $this WP_Meta_Query object.
*/
return apply_filters( 'meta_query_find_compatible_table_alias', $alias, $clause, $parent_query, $this ) ;
}
}
/**
* Retrieve the name of the metadata table for the specified object type.
*
* @since 2.9.0
*
* @global wpdb $wpdb WordPress database abstraction object.
*
* @param string $type Type of object to get metadata table for (e.g., comment, post, or user)
* @return mixed Metadata table name, or false if no metadata table exists
*/
function _get_meta_table($type) {
global $wpdb;
$table_name = $type . 'meta';
if ( empty($wpdb->$table_name) )
return false;
return $wpdb->$table_name;
}
/**
* Determine whether a meta key is protected.
*
* @since 3.1.3
*
* @param string $meta_key Meta key
* @param string|null $meta_type
* @return bool True if the key is protected, false otherwise.
*/
function is_protected_meta( $meta_key, $meta_type = null ) {
$protected = ( '_' == $meta_key[0] );
/**
* Filter whether a meta key is protected.
*
* @since 3.2.0
*
* @param bool $protected Whether the key is protected. Default false.
* @param string $meta_key Meta key.
* @param string $meta_type Meta type.
*/
return apply_filters( 'is_protected_meta', $protected, $meta_key, $meta_type );
}
/**
* Sanitize meta value.
*
* @since 3.1.3
*
* @param string $meta_key Meta key
* @param mixed $meta_value Meta value to sanitize
* @param string $meta_type Type of meta
* @return mixed Sanitized $meta_value
*/
function sanitize_meta( $meta_key, $meta_value, $meta_type ) {
/**
* Filter the sanitization of a specific meta key of a specific meta type.
*
* The dynamic portions of the hook name, `$meta_type`, and `$meta_key`,
* refer to the metadata object type (comment, post, or user) and the meta
* key value,
* respectively.
*
* @since 3.3.0
*
* @param mixed $meta_value Meta value to sanitize.
* @param string $meta_key Meta key.
* @param string $meta_type Meta type.
*/
return apply_filters( "sanitize_{$meta_type}_meta_{$meta_key}", $meta_value, $meta_key, $meta_type );
}
/**
* Register meta key
*
* @since 3.3.0
*
* @param string $meta_type Type of meta
* @param string $meta_key Meta key
* @param string|array $sanitize_callback A function or method to call when sanitizing the value of $meta_key.
* @param string|array $auth_callback Optional. A function or method to call when performing edit_post_meta, add_post_meta, and delete_post_meta capability checks.
*/
function register_meta( $meta_type, $meta_key, $sanitize_callback, $auth_callback = null ) {
if ( is_callable( $sanitize_callback ) )
add_filter( "sanitize_{$meta_type}_meta_{$meta_key}", $sanitize_callback, 10, 3 );
if ( empty( $auth_callback ) ) {
if ( is_protected_meta( $meta_key, $meta_type ) )
$auth_callback = '__return_false';
else
$auth_callback = '__return_true';
}
if ( is_callable( $auth_callback ) )
add_filter( "auth_{$meta_type}_meta_{$meta_key}", $auth_callback, 10, 6 );
}