Attempting to have cart update each value individually instead of updating all of them-CodePudding

I am making an e-commerce website and I have run into an issue with updating item quantity. When I go back to the same page of an item already in my cart and put in a new quantity, I return to my cart page and all of the items now have the same quantity as the item last updated.

if (!isset($_SESSION['shoppingcart'])) {
        $_SESSION['shoppingcart'] = array();
        $_SESSION['name'] = array();
        $_SESSION['quantity'] = array();
        $_SESSION['price'] = array();
    }

    if (in_array($_POST['id'], $_SESSION['shoppingcart'])) {
        for ($i = 0; $i < sizeof($_SESSION['quantity']); $i  ) {

            $_SESSION['quantity'][$i] = $_POST['quantity']; /*<-- I am thinking it is this piece right here.*/

            removeItemsZero($i);
            $added = '<p >Updated cart! Click <a href="catalog.php">here</a> to continue shopping!</p>';
        }
    } else {
            $_SESSION['shoppingcart'][] = $_POST['id'];
            $_SESSION['quantity'][] = $_POST['quantity'];
            $_SESSION['name'][] = $name;
            $_SESSION['price'][] = $price;
            $added = '<p >Product added! Click <a href="catalog.php">here</a> to continue shopping!</p>';
        }

I am assuming it has something to do with $_SESSION['quantity'][$i] = $_POST['quantity']; piece, but I am unsure of any other ways to update the quantity on the product description page.

EDIT

I changed some things around, but now regardless of whichever product from the product page I select, I can't seem to change the quantity of that item specifically, but that value I enter into the field gets applied to the first index of the quantity array.

if (in_array($_POST['id'], $_SESSION['shoppingcart'])) {
        $key = array_search($_POST['id'], $_SESSION['quantity']);
            $_SESSION['quantity'][$key] = $_POST['quantity'];
        for ($i = 0; $i < sizeof($_SESSION['quantity']); $i  ) {
            removeItemsZero($i);
            $added = '<p >Updated cart! Click <a href="catalog.php">here</a> to continue shopping!</p>';
        }

EDIT2

This is the code for the cart page with checkout

$cartTable = '<table >';
$tableHeader = '<tr><th>NAME</th><th>QUANTITY</th><th>PRICE</th><th>TOTAL</th></tr>';
$endTable = '</table>';
$total = 0;
$totalDiscounted = 0;
$emptyCart = '';
$msg = '';
if (!empty($_SESSION['shoppingcart'])) {
    $conn = mysqli_connect(HOST, USER, PASS, DB);
    if (isset($_POST['update'])) {
        for ($i = 0; $i < sizeof($_SESSION['quantity']); $i  ) {
            $postID = 'qty' . $i;
            $_SESSION['quantity'][$i] = $_POST[$postID];
            removeItemsZero($i);
        }
    }
}
if (isset($_POST['purchase'])) {
    $msg = '<p>Thanks for purchasing! This is what you ordered</p><br>';
    for ($i = 0; $i < sizeof($_SESSION['shoppingcart']); $i  ) {
        $list .= '<div ><p >Order List</p><ul><li>' . $_SESSION['quantity'][$i] . ' ' . $_SESSION['name'][$i] . '</li></ul></div>';
    }
    unset($_SESSION['shoppingcart']);
}
if (isset($_POST['clear'])) {
    unset($_SESSION['shoppingcart']);
    $emptyCart = '<p>Your cart is empty!</p>';
} else if(isset($_POST['purchase'])){
    $emptyCart = '<p>Your cart is now empty!</p>';
}else
{
    $emptyCart = '<p>Your cart is empty!</p>';
}
?>
<!doctype html>
<html lang="en">
<head>
    <script src="js/script.js"></script>
    <link rel="stylesheet" href="css/style.css" type="text/css">
    <title>Acme Online Store - cart</title>
</head>
<body>
<nav>
    <div ><h2>Acme Online Store</h2></div>
    <ul>
        <li><a href="catalog.php">Products</a></li>
        <li><a  href="cart.php">Cart</a></li>
        <li><a href="logout.php">Log Out</a></li>
    </ul>
</nav>

<div >
    <form method="post">
        <?php
        if (!empty($_SESSION['shoppingcart'])) {
        for ($i = 0; $i < sizeof($_SESSION['shoppingcart']); $i  ) {
            $cart .= '<tr>';
            $cart .= '<td>' . $_SESSION['name'][$i] . '</td>';
            $cart .= '<td><input type="text" id="quantity"name="qty' . $i . '"value="' . $_SESSION['quantity'][$i] . '" onkeyup="checkInput()"></td>';
            $cart .= '<td>$' . $_SESSION['price'][$i] . '</td>';
            $cart .= '<td>$' . $_SESSION['quantity'][$i] * $_SESSION['price'][$i] . '</td>';
            $cart .= '</tr>';
            $total  = ($_SESSION['quantity'][$i] * $_SESSION['price'][$i]);
            $totalDiscounted  = ($_SESSION['quantity'][$i] * $_SESSION['price'][$i]) / 100 * 30;
        }
        echo $cartTable;
        echo $tableHeader;
        echo $cart;
        echo $endTable;
        echo '<br>';
        echo '<p>All orders are 30% off for the holidays!</p><br>';
        echo '<table >';
        echo '<tr>';
        echo '<th>Total</th><th>Total After Discount</th><th>Savings</th></tr>';
        echo '<tr><td> $' . $total . '</td>';
        echo '<td>$' . number_format((float)$total - $totalDiscounted, 2, '.', '') . '</td>';
        echo '<td>$' . number_format((float)$totalDiscounted, 2, '.', '') . '</td>';
        echo '</tr>';
        echo '</table>';
        ?>

CodePudding user response：

It would be better to include a self-contained example, but here is one method. We are saving the ID as the key to an array. That is, array(1 => array(quantity = 10)); would be the data structure of the items within our shopping cart. This approach means we are determining whether the key exists and then updating shopping cart array.

<?php
session_start();
if (!isset($_SESSION['shoppingcart'])) {
    $_SESSION['shoppingcart'] = array();
}
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $postId = cleanInput($_POST["id"]);
    $postQuantity = cleanInput($_POST['quantity']);
    if (!empty($_SESSION['shoppingcart'][$postId])) {
        $_SESSION['shoppingcart'][$postId]['quantity'] = $postQuantity;
        // you can add code that you updated existing record
    } else {
        $_SESSION['shoppingcart'][$postId] = array("quantity" => $postQuantity);
        // you can add code that you added a new record
    }
}

function cleanInput(string $data) : string
{
    $data = trim($data); // removes whitespace
    $data = stripslashes($data); // strips slashes
    $data = htmlspecialchars($data); // replaces html chars
    return $data;
}
?>
<!DOCTYPE html>
<html>
    <head>
        <title>My Shopping Cart</title>
    </head>
    <body>
        <form method = "post" action="<?php echo $_SERVER['PHP_SELF']; ?>">
            <label for = "id" name = "id">Enter Id</input><br>
            <input type="number" for = "id" name = "id" required><br>
            <label for = "quantity" name = "quantity">Enter Quantity</input><br>
            <input type="number" for = "quantity" name = "quantity" required><br> 
            <input type="submit">
        </form>
        <?php 
            if (count($_SESSION['shoppingcart']) == 0) {
                echo "<h2>No orders entered!</h2>";
            } else {
                echo "<table>
                        <thead>
                            <tr>
                                <th>id</th>
                                <th>quantity</th>
                            </tr>
                        </thead>
                        <tbody>";
                foreach($_SESSION['shoppingcart'] as $id =>$shoppingItem) {
                    $quantityRes = $shoppingItem['quantity'];
                    echo "<tr><td>$id</td><td>$quantityRes</td></tr>";
                }
                echo " </tbody></table>";
            }
        ?>
    </body>
<html>