[Forminator Pro] - Prevent duplicate entries. Allow to filter values and prevent duplicate entries for selected forms and fields

wpmudev-forminator-duplicate-field-values.php

<?php
/**
* Plugin Name: [Forminator Pro] - Prevent duplicate entries
* Plugin URI: https://premium.wpmudev.org/
* Description: Allow to filter values and prevent duplicate entries for selected forms and fields (as of 1.8.1)
* Author: Alessandro Kaounas @ WPMUDEV
* Author URI: https://premium.wpmudev.org/
* License: GPLv2 or later
*/

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

if ( ! class_exists( 'WPMUDEV_Forminator_Duplicate_Entries' ) ) {
    
    class WPMUDEV_Forminator_Duplicate_Entries {

        private static $_instance = null;

		private $fields_to_check = array(
            // User defined - One form per line with selected fields (must exists in forms' settings)
            // Example: $form_id => array('field-1', 'field-2', ..., 'field-n')
			1097 => array( 'email-1' )
        );

        public static function get_instance() {

            if( is_null( self::$_instance ) ){
                self::$_instance = new WPMUDEV_Forminator_Duplicate_Entries();
            }
            return self::$_instance;
            
        }

        private function __construct() {
            add_filter( 'forminator_custom_form_submit_errors', array( $this, 'forminator_avoid_duplicate_entries'), 999, 3 );  	
        }

        function forminator_avoid_duplicate_entries($entry, $form_id, $field_data_array){
            if( empty( $this->fields_to_check[$form_id] ) ) return $entry;
			global $wpdb;
			$duplicate = false;
			$frmt_form_entry = $wpdb->prefix . 'frmt_form_entry';
			$frmt_form_entry_meta = $wpdb->prefix . 'frmt_form_entry_meta';
                        foreach($this->fields_to_check as $form){
                            foreach($form as $field){
                                $field_key = array_search($field, array_column($field_data_array, 'name'));
                                if($field_key === false) continue;
                                $sql_query = "SELECT COUNT(`meta_value`) FROM `$frmt_form_entry_meta` WHERE `entry_id` IN (SELECT `entry_id` FROM `$frmt_form_entry` WHERE `form_id` = $form_id) AND `meta_key` = '$field' AND `meta_value` = '%s' GROUP BY `meta_value`;";
                                if( $wpdb->query( $wpdb->prepare( $sql_query, $field_data_array[$field_key]['value'] ) ) ){
                                    $duplicate = true;
                                    break;
                                }
                            }
                        }

			if(!$duplicate) return $entry;
            
			// Just in case something has changed in database schema
			if(($wpdb->get_var("SHOW TABLES LIKE '$frmt_form_entry';") != $frmt_form_entry) || 
			($wpdb->get_var("SHOW TABLES LIKE '$frmt_form_entry_meta';") != $frmt_form_entry_meta)) return $entry;
			$response = array(
				'message' => __( 'The survey with similar data has been already submitted / A felmérés a megadott adatokkal már rögzítésre került', 'forminator' ),
				'success' => false,
				'errors'  => array(),
				'behav'   => ''
			);
			echo wp_send_json(['success' => false, 'data' => $response]);
			return $entry;
		}

	}
	
    if ( ! function_exists( 'wpmudev_forminator_avoid_duplicate_entries' ) ) {
        
        function wpmudev_forminator_avoid_duplicate_entries() {
            return WPMUDEV_Forminator_Duplicate_Entries::get_instance();
        };

        add_action( 'plugins_loaded', 'wpmudev_forminator_avoid_duplicate_entries', 99 );
    }

}