[Forminator Pro] - Multiselect minimum and maximum selection.

forminator-multiselect-minimum-maximum-selection.php

<?php
/**
 * Plugin Name: [Forminator Pro] Allow maximum and minimum slection.
 * Description: Removes default/empty option and adds maximum and minimum selection limit in modern multiselects.
 * Author: Prashant @ WPMUDEV
 * Task: SLS-6254
 * Author URI: https://premium.wpmudev.org
 * License: GPLv2 or later
 */

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

add_action( 'forminator_before_form_render', 'wpmudev_select_data_form_check', 10, 5 );
function wpmudev_select_data_form_check( $id, $form_type, $post_id, $form_fields, $form_settings ) {
	$form_ids = array( 2960 ); // Please change the form ID.
	if ( in_array( intval( $id ), $form_ids, true ) ) {
		add_filter( 'forminator_field_single_markup', 'wpmudev_unset_default_selection_unchecked', 10, 4 );
	}
}

// Removes default selection and adds minimum selection limit.
function wpmudev_unset_default_selection_unchecked( $html, $id, $required, $options ) {
	$field_ids = array(
		'select-1' => 2,
		'select-2' => 3,
	); // Please match the field IDs and min selection.

	foreach ( $field_ids as $key => $value ) {
		if ( false !== strpos( $html, '<select multiple' ) && $required && false !== strpos( $id, 'field--' . $key ) ) {
			$html = str_replace( '<select multiple', '<select multiple minlength="' . $value . '"', $html );
			$html = str_replace( 'value="" selected="selected"', 'value=""', $html );
		}
	}

	return $html;
}

// Adds maximum selection limit and defines error messages.
add_action( 'wp_footer', 'wpmudev_select_selection_min_max', 9999 );
function wpmudev_select_selection_min_max() {
	global $post;
	if ( is_a( $post, 'WP_Post' ) && ! has_shortcode( $post->post_content, 'forminator_form' ) ) {
		return;
	}
	?>
	<script type="text/javascript">
	jQuery(document).ready(function($){
		setTimeout(function() {
			$('.forminator-custom-form').trigger('after.load.forminator');
		},500);
		
		$(document).on('after.load.forminator', function(e, form_id) {
			if ( 'forminator-module-2960' === e.target.id ) { // Please change the form ID.
				$.validator.addMethod("maxselection", function (value, element) {
					if ( $.isArray( value ) && value.length > $(element).attr('data-max') ) {
						return false;
					}
					return true;
				});
				
				var select_max = {'select-1': 3, 'select-2': 4 }; // Please match the field IDs and max selection.
				$.each(select_max, function(index, item) {
					$('#' + e.target.id + ' #' + index + ' select').attr('data-max', item);
					var minlength = $('#' + e.target.id + ' #' + index + ' select').attr('minlength');
					$('#' + e.target.id + ' #' + index + ' select').rules("add", {
						'maxselection': true,
						messages: {
							minlength: 'Please select at least ' + minlength + ' options.',
							maxselection: 'Maximum ' + item + ' options allowed.'
						}
					});
				});
			}
		});
	});
	</script>
	<?php
}