Source
File: wp-includes/meta.php
function register_meta( $object_type, $meta_key, $args, $deprecated = null ) {
global $wp_meta_keys;
if ( ! is_array( $wp_meta_keys ) ) {
$wp_meta_keys = array();
}
$defaults = array(
'object_subtype' => '',
'type' => 'string',
'description' => '',
'default' => '',
'single' => false,
'sanitize_callback' => null,
'auth_callback' => null,
'show_in_rest' => false,
);
// There used to be individual args for sanitize and auth callbacks.
$has_old_sanitize_cb = false;
$has_old_auth_cb = false;
if ( is_callable( $args ) ) {
$args = array(
'sanitize_callback' => $args,
);
$has_old_sanitize_cb = true;
} else {
$args = (array) $args;
}
if ( is_callable( $deprecated ) ) {
$args['auth_callback'] = $deprecated;
$has_old_auth_cb = true;
}
/**
* Filters the registration arguments when registering meta.
*
* @since 4.6.0
*
* @param array $args Array of meta registration arguments.
* @param array $defaults Array of default arguments.
* @param string $object_type Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
* or any other object type with an associated meta table.
* @param string $meta_key Meta key.
*/
$args = apply_filters( 'register_meta_args', $args, $defaults, $object_type, $meta_key );
unset( $defaults['default'] );
$args = wp_parse_args( $args, $defaults );
// Require an item schema when registering array meta.
if ( false !== $args['show_in_rest'] && 'array' === $args['type'] ) {
if ( ! is_array( $args['show_in_rest'] ) || ! isset( $args['show_in_rest']['schema']['items'] ) ) {
_doing_it_wrong( __FUNCTION__, __( 'When registering an "array" meta type to show in the REST API, you must specify the schema for each array item in "show_in_rest.schema.items".' ), '5.3.0' );
return false;
}
}
$object_subtype = ! empty( $args['object_subtype'] ) ? $args['object_subtype'] : '';
// If `auth_callback` is not provided, fall back to `is_protected_meta()`.
if ( empty( $args['auth_callback'] ) ) {
if ( is_protected_meta( $meta_key, $object_type ) ) {
$args['auth_callback'] = '__return_false';
} else {
$args['auth_callback'] = '__return_true';
}
}
// Back-compat: old sanitize and auth callbacks are applied to all of an object type.
if ( is_callable( $args['sanitize_callback'] ) ) {
if ( ! empty( $object_subtype ) ) {
add_filter( "sanitize_{$object_type}_meta_{$meta_key}_for_{$object_subtype}", $args['sanitize_callback'], 10, 4 );
} else {
add_filter( "sanitize_{$object_type}_meta_{$meta_key}", $args['sanitize_callback'], 10, 3 );
}
}
if ( is_callable( $args['auth_callback'] ) ) {
if ( ! empty( $object_subtype ) ) {
add_filter( "auth_{$object_type}_meta_{$meta_key}_for_{$object_subtype}", $args['auth_callback'], 10, 6 );
} else {
add_filter( "auth_{$object_type}_meta_{$meta_key}", $args['auth_callback'], 10, 6 );
}
}
if ( array_key_exists( 'default', $args ) ) {
$schema = $args;
if ( is_array( $args['show_in_rest'] ) && isset( $args['show_in_rest']['schema'] ) ) {
$schema = array_merge( $schema, $args['show_in_rest']['schema'] );
}
$check = rest_validate_value_from_schema( $args['default'], $schema );
if ( is_wp_error( $check ) ) {
_doing_it_wrong( __FUNCTION__, __( 'When registering a default meta value the data must match the type provided.' ), '5.5.0' );
return false;
}
if ( ! has_filter( "default_{$object_type}_metadata", 'filter_default_metadata' ) ) {
add_filter( "default_{$object_type}_metadata", 'filter_default_metadata', 10, 5 );
}
}
// Global registry only contains meta keys registered with the array of arguments added in 4.6.0.
if ( ! $has_old_auth_cb && ! $has_old_sanitize_cb ) {
unset( $args['object_subtype'] );
$wp_meta_keys[ $object_type ][ $object_subtype ][ $meta_key ] = $args;
return true;
}
return false;
}