add_(meta_type)_metadata │ filter-hook │ WP 3.1.0

Short-circuits adding metadata of a specific type.

The dynamic portion of the hook name, $meta_type, refers to the meta object type (blog, post, comment, term, user, or any other type with an associated meta table). Returning a non-null value will effectively short-circuit the function.

Possible hook names include:

• add_blog_metadata
• add_post_metadata
• add_comment_metadata
• add_term_metadata
• add_user_metadata

Usage

add_filter( 'add_(meta_type)_metadata', 'wp_kama_add_meta_type_metadata_filter', 10, 5 );

/**
 * Function for `add_(meta_type)_metadata` filter-hook.
 * 
 * @param null|int|false $check      Whether to allow adding metadata for the given type. Return false or a meta ID to short-circuit the function. Return null to continue with the default behavior.
 * @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     Whether the specified meta key should be unique for the object.
 *
 * @return null|int|false
 */
function wp_kama_add_meta_type_metadata_filter( $check, $object_id, $meta_key, $meta_value, $unique ){

	// filter...
	return $check;
}

$check(null|int|false)

Whether to allow adding metadata for the given type. Return false or a meta ID to short-circuit the function. Return null to continue with the default behavior.

$object_id(int)

ID of the object metadata is for.

$meta_key(string)

Metadata key.

$meta_value(mixed)

Metadata value. Must be serializable if non-scalar.

$unique(true|false)

Whether the specified meta key should be unique for the object.

Changelog

Where the hook is called

$check = apply_filters( "add_{$meta_type}_metadata", null, $object_id, $meta_key, $meta_value, $unique );

Where the hook is used in WordPress

add_filter( 'add_term_metadata', 'wp_check_term_meta_support_prefilter' );

add_filter( 'add_blog_metadata', 'wp_check_site_meta_support_prefilter' );