File: /var/www/Gosurya/WP2/wp-content/themes/my-listing/includes/src/forms/fields/multiselect-field.php
<?php
namespace MyListing\Src\Forms\Fields;
if ( ! defined('ABSPATH') ) {
	exit;
}
class Multiselect_Field extends Base_Field {
	public $modifiers = [
		'labels' => '%s Label(s)',
	];
	public function get_posted_value() {
		return isset( $_POST[ $this->key ] )
			? array_map( 'sanitize_text_field', $_POST[ $this->key ] )
			: [];
	}
	public function validate() {
		$value = $this->get_posted_value();
		$this->validateSelectedOption();
	}
	public function field_props() {
		$this->props['type'] = 'multiselect';
		$this->props['options'] = new \stdClass; // when encoded to json, it needs to be {} instead of [].
	}
	public function get_editor_options() {
		$this->getLabelField();
		$this->getKeyField();
		$this->getPlaceholderField();
		$this->getDescriptionField();
		$this->getRequiredField();
		$this->getShowInSubmitFormField();
		$this->getShowInAdminField();
		$this->getOptionsField();
	}
	public function string_value( $modifier = null ) {
		$selected = (array) $this->get_value();
		$options = $this->get_prop('options');
		$validated = [];
		// validate selected options and retrieve their labels
		foreach ( $selected as $value ) {
			if ( isset( $options[ $value ] ) ) {
				$validated[ $value ] = $options[ $value ];
			}
		}
		if ( $modifier === 'labels' ) {
			return join( ', ', $validated );
		}
		return join( ', ', array_keys( $validated ) );
	}
}