Notice: Undefined index: languageval. What is the problem?

Z

Zina-20002021-06-08 21:59:20

PHP

Zina-2000, 2021-06-08 21:59:20

Hello! I write linked lists with data loading from the database. I am writing from a video tutorial. I don't understand why I get the error "Notice: Undefined index: languageval in /opt/lampp/htdocs/Lesko/select-registration.php on line 5". Because of it, the selection options from the second select are not loaded. How to fix?

Page code with selects:

<?php

require_once "function.php";

if($_POST['languageval']) {
  $return = selectCountries();
  exit($return);
}

$languages = selectLanguages();
?>
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
  <script src="lists.js"></script>
  <style>
    form div{margin: 0 0 15px 0;}
    #divcountry, #divgenre {display: none;}
  </style>
</head>
<body>


<div class="choise">
  <form action="" method="post">
    <div>
      <select name="language" id="language">
        <option value="0">выберете язык</option>
      <?php foreach ($languages as $language): ?>
        <option value="<?=$language['id_language']?>"><?=$language['language']?></option>
      <?php endforeach; ?>
      </select>
    </div>

    <div>
      <select disabled name="country" id="country">
        <option value="0">выберете страну</option>
      </select>
    </div>

    <div>
      <select disabled name="genre" id="genre">
        <option value="0">выберете жанр</option>
      </select>
    </div>
</div>


</body>
</html>

lists.js page code

/*global $ , jQuery*/
/*jslint browser:true */


$(document).ready(function () {
    "use strict";
    $("#language").change(function () {
        var languageval = parseInt($("#language").val(), 10);
        selectCountries(languageval);
    });
});

function selectCountries(languageval) {
    "use strict";
    var country = $("#country");

    if (languageval > 0) {
        $("#divcountry");
        country.attr("disabled", false);
        country.load(
            "select-registration.php",
            {languageval: languageval}
        );
    }
}

function page code:

<?php
$GLOBALS['link'] = mysqli_connect("localhost", "root", "", "lesko") or die ("Нет соединения");
mysqli_set_charset($link, 'utf8');
?>

<?php

function selectLanguages () {
  $query = "SELECT * FROM languages_";
  $res = mysqli_query($GLOBALS['link'], $query);
  $languages = array();
  while ($row = mysqli_fetch_assoc($res)) {
    $languages[] = $row;
  }
  return $languages;
}


function selectCountries() {
  $languageval = (int)$_POST['languageval'];
  $query = "SELECT * FROM countries_ WHERE id_language = $languageval";
  $res = mysqli_query($query);
  $return = "<option value='0'>выберете страну</option>";
  while ($row = mysqli_fetch_assoc($res)){
    $return .="<option value='{$row['id_country']}'>{$row['country']}</option>";
  }
  return $return;
}