Warning: Undefined array key "Item_ID" - php

Question

I'm having a problem with PHP code. I got some code from an e-book, but when I tried to run the system, it's giving some errors. I fixed some of the errors by giving proper quotation marks, but now I'm stuck with some other errors.
I'd be more than happy if someone helps me with the following error:
Warning: Undefined array key "Item_ID" in C:\xampp\htdocs\eCommerce\order.php on line 13
This is my code for order.php:
<?php
ob_start();
session_start();
if (isset ($_SESSION['Username'])){
$pageTitle ='Order';
include 'init.php';
?>
<div class="container">
<div class="row">
<?php
$Allitem = getAllFrom('items','Item_ID');
if ($_GET['Item_ID']){
foreach($Allitem as $item){
echo '<div class="col-sm-6 col-md-4">';
echo '<div class="thumbnail item-box">';
echo '<span class="price-tag">$ ' . $item['Price'] . '</span>';
echo ' <img class="img-responsive" src="../eCommerce/admin/layout/images/'. $item['Image'].' " alt="No Image Uploaded" />';
echo '<div class="caption">';
echo '<h3 class="items-name">'.$item['Name'] .'</h3>';
echo '</div>';
echo '</div>';
echo '</div>';
}
}
}
?>
</div>
<?php
include $tpl .'footer.php';
ob_end_flush();
?>

Answer 1

You are calling the index which is not in you $_GET parameters. You have to verify that the parameter is present or not. For this you have to change your if condition from
if($_GET['Item_ID']){
....
}
to
if(isset($_GET['Item_ID'])){
....
}
this will verify that the required parameter is present or not