Complication de code dans la creation de shopping cart

je veux creer un shopping mais le browser n'arrive pas a trouver mon array et il m'envois ce message

Notice: Undefined index: item_name in C:\xampp\htdocs\Ecommerce_master\index.php on line 166
Notice: Undefined index: item_quantity in C:\xampp\htdocs\Ecommerce_master\index.php on line 167
Notice: Undefined index: item_price in C:\xampp\htdocs\Ecommerce_master\index.php on line 168

Notice: Undefined index: item_quantity in C:\xampp\htdocs\Ecommerce_master\index.php on line 169

il


voici mes codes

<?php

    session_start();

    $connect = mysqli_connect("localhost", "root", "", "manage_articles");  

    if(isset($_POST["add_to_cart"]))
    {
        if(isset($_SESSION["shopping _cart"]))
        {
            $item_array_id = array_column($_SESSION["shopping_cart"], "item_id");
            if(!in_array($_GET["id"], $item_array_id))
            {
                $count = count($_SESSION["shopping_cart"]);
                $item_array = array(
                   'item_id'        => $_GET["id"],
                   'item_name'      => $_POST["hidden_name"],
                   'item_price'     => $_POST["hidden_price"],
                   'item_quantity'  => $_POST["quantity"]
                );

                $_SESSION["shopping_cart"][$count] = $item_array;

            }
            else
            {
                echo "<script> alert('Item Already added'); </script>";
                echo "<script> window.location'index.php' </script>";
            }
        }
        else
        {
            $item_array = array(
                '$item_id'      => $_GET["id"],
                '$item_name'    => $_POST["hidden_name"],
                '$item_price'   => $_POST["hidden_price"],
                '$item_quantity' => $_POST["quantity"]
            );

            $_SESSION["shopping_cart"][0] = $item_array;
        }
    }


//===================================

<?php

        $query = "SELECT * FROM tbl_product ORDER BY id ASC";
        $result = mysqli_query($connect, $query);
        if(mysqli_num_rows($result) > 0)
        {
            while($row = mysqli_fetch_array($result))
            {
    ?>

        <div class="col-md-3">
             <form method="post" action="index.php?action=add&id=<?php echo $row["id"]; ?>"> 
                <div id="espace_product">
                    <img src="<?php echo $row["img"]; ?>" class="img-responsive"><br>
                    <h4 class="text-info"><?php echo $row["name"]; ?></h4>
                    <h4 class="text-danger">$<?php echo $row["price"]; ?></h4>
                    <input type="text" name="quantity" class="form-control" value="1" />
                    <input type="hidden" name="hidden_name" value="<?php echo $row["name"]; ?>" />
                    <input type="hidden" name="hidden_price" value="<?php echo $row["price"]; ?>" />
                    <input type="submit" name="add_to_cart" style="margin-top:5px;" class="btn btn-danger" value="Add to Card" />
                </div>     
             </form>
        
        </div>
    
    <?php
            }
        }
    
    ?>
//======================================================

<tr>
                <th width="40%"> Item Name</th>
                <th width="10%"> Quatity</th>
                <th width="20%"> Price</th>
                <th width="15%"> Total</th>
                <th width="5%"> Action</th>
            </tr>
            <?php 
                if(!empty($_SESSION["shopping_cart"]))
                {
                    $total = 0;
                    foreach($_SESSION["shopping_cart"] as $keys => $values)
                    {
            ?>
                <tr>
                    <td><?php echo $values["item_name"]; ?></td>
                    <td><?php echo $values["item_quantity"]; ?></td>
                    <td>$ <?php echo $values["item_price"]; ?></td>
                    <td><?php echo number_format($values["item_quantity"] * $values["item_price"], 2); ?></td>
                    <td> <a href="index.php?action=delete&id=<?php echo $values["item_id"]; ?>"><span class="text-danger">Remove</a></span></td>
                </tr>
            <?php

                $total = $total + ($values["item_quantity"] * $values["item_price"]);
                    
                    }
            ?>

                <tr>
                    <td colspan="3" align="right">Total</td>
                    <td align="right">$ <?php echo number_format($total, 2); ?></td>
                    <td></td>
                </tr>

            <?php

EDIT : Ajout des balises de code