sanitize_meta() │ WP 3.1.3

Clears the value of meta data. The function itself does nothing, but applies the filter "sanitize_{$meta_type}_meta_{$meta_key}", through which different meta data can be sanitized differently.

This function is used in all functions when adding/updating WordPress metadata: update_*_meta() or add_*_meta() — update_post_meta(), update_term_meta(), update_user_meta(), update_comment_meta().

Hooks from the function

Returns

Mixed. Processed value of the meta-field.

Usage

sanitize_meta( $meta_key, $meta_value, $object_type, $object_subtype );
$meta_key(string) (required)
Key of the meta-field. Used in the name of the filter, based on which the value $meta_value is sanitized.
$meta_value(mixed) (required)
Value to be sanitized.
$object_type(string) (required)
Type of metadata. Can be: comment, post, user, term. Used in the name of the filter, based on which the value $meta_value is sanitized.
$object_subtype(string)
Type of the object for which the meta-field was created. For example, post. If an empty string is passed, it means that the meta-field is registered for any object. See the parameter of the same name in the function register_meta().

Examples

0

#1 Example of cleaning a custom field, with a custom function. 

// clear the value through the added function, somewhere in another file...
$clean_value = sanitize_meta( 'birth-year', $user_input, 'user' );

// add our cleaning function
add_filter( 'sanitize_user_meta_'.'birth-year', 'sanitize_birth_year_meta' );

function sanitize_birth_year_meta( $year ) {

	$now = date( 'Y' );
	$then = $now - 50; // User not older than 50

	if ( $then > $year || $year > $now )
		wp_die( 'Incorrect input, go back and try again.' );

	return $year;
}

Changelog

Since 3.1.3 Introduced.
Since 4.9.8 The $object_subtype parameter was added.

sanitize_meta() code WP 6.9.1

wp-includes/meta.php 
function sanitize_meta( $meta_key, $meta_value, $object_type, $object_subtype = '' ) {
	if ( ! empty( $object_subtype ) && has_filter( "sanitize_{$object_type}_meta_{$meta_key}_for_{$object_subtype}" ) ) {

		/**
		 * Filters the sanitization of a specific meta key of a specific meta type and subtype.
		 *
		 * The dynamic portions of the hook name, `$object_type`, `$meta_key`,
		 * and `$object_subtype`, refer to the metadata object type (blog, comment, post, term, or user),
		 * the meta key value, and the object subtype respectively.
		 *
		 * @since 4.9.8
		 *
		 * @param mixed  $meta_value     Metadata value to sanitize.
		 * @param string $meta_key       Metadata key.
		 * @param string $object_type    Type of object metadata is for. Accepts 'blog', 'post', 'comment', 'term',
		 *                               'user', or any other object type with an associated meta table.
		 * @param string $object_subtype Object subtype.
		 */
		return apply_filters( "sanitize_{$object_type}_meta_{$meta_key}_for_{$object_subtype}", $meta_value, $meta_key, $object_type, $object_subtype );
	}

	/**
	 * Filters 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 (blog, comment, post, term, or user) and the meta
	 * key value, respectively.
	 *
	 * @since 3.3.0
	 *
	 * @param mixed  $meta_value  Metadata value to sanitize.
	 * @param string $meta_key    Metadata key.
	 * @param string $object_type Type of object metadata is for. Accepts 'blog', 'post', 'comment', 'term',
	 *                            'user', or any other object type with an associated meta table.
	 */
	return apply_filters( "sanitize_{$object_type}_meta_{$meta_key}", $meta_value, $meta_key, $object_type );
}

sanitize_

Metadatas (any)