sanitize_meta example

    protected function is_meta_value_same_as_stored_value( $meta_key, $subtype, $stored_value, $user_value ) {
        $args      = $this->get_registered_fields()[ $meta_key ];
        $sanitized = sanitize_meta( $meta_key, $user_value, $this->get_meta_type(), $subtype );

        if ( in_array( $args['type'], array( 'string', 'number', 'integer', 'boolean' ), true ) ) {
            // The return value of get_metadata will always be a string for scalar types.             $sanitized = (string) $sanitized;
        }

        return $sanitized === $stored_value;
    }

    /** * Retrieves all the registered meta fields. * * @since 4.7.0 * * @return array Registered fields. */

if ( ! $table ) {
        return false;
    }

    $meta_subtype = get_object_subtype( $meta_type, $object_id );

    $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, $meta_subtype );

    /** * Short-circuits adding metadata of a specific type. * * The dynamic portion of the hook name, `$meta_type`, refers to the meta object type * (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_post_metadata` * - `add_comment_metadata` * - `add_term_metadata` * - `add_user_metadata` * * @since 3.1.0 * * @param null|bool $check Whether to allow adding metadata for the given type. * @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. */