[Forminator Pro] - Send unchecked options in the mail

forminator-unchecked-options-mail.php

<?php
/**
 * Plugin Name: [Forminator Pro] Send unchecked options only in mail.
 * Description: Sends unchecked options of a checkbox in the mail.
 * Author: Prashant @ WPMUDEV
 * Task: SLS-6301
 * Author URI: https://premium.wpmudev.org
 * License: GPLv2 or later
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit; // Exit if accessed directly.
}

add_filter( 'forminator_custom_form_after_render_value', function( $value, $custom_form, $field_slug, $prepared_data ) {
	if ( 2960 !== intval( $custom_form->id ) ) { // Please change the form ID.
		return $value;
	}

	if ( 'checkbox-1' === $field_slug && ! empty( $value ) ) { // Please change the field ID.
		$check_field   = $custom_form->get_field( $field_slug, true );
		$field_options = ! empty( $check_field['options'] ) ? wp_list_pluck( $check_field['options'], 'label', 'value' ) : array();
		if ( ! empty( $field_options ) ) {
			foreach ( $prepared_data[ $field_slug ] as $key => $option ) {
				if ( array_key_exists( $option, $field_options ) ) {
					unset( $field_options[ $option ] );
				}
			}
		}

		$value = implode( ', ', array_keys( array_flip( $field_options ) ) );
	}
	return $value;
}, 10, 4 );