(PHP) Shopping Cart - php

Question

I am trying to create a shopping cart with PHP, but, once the user leaves the cart area, all of the products disappear. That's what I'm trying to do:
<?php foreach($almofadas as $almofadas):?>
<form action="cart.php" method="GET">
<div class="base col-6 col-sm-4 col-md-5 col-lg-4 col-xl-4">
<div class="card">
<img src="uploads/<?php echo $almofadas['imagem']; ?>" alt="">
<div class="content-c">
<div class="row-p">
<div class="details">
<span><?php echo $almofadas['pnome'] ; ?></span>
</div>
<div class="price">R$ <?php echo $almofadas['preço'];?> </div>
</div>
<input type="hidden" name="id" value="<?php echo $almofadas['p_id']?>">
<div style="margin-top: 10px;">
<div style="margin-bottom: 5px;"><button class="buttons-1" data-toggle="modal" data-target="#myModal">Detalhes</button></div>
<div><button class="buttons-2" type="submit">Adicionar ao Carrinho</a> </button></div>
</div>
</div>
</div>
</div>
</form>
<?php endforeach; ?>
Now the cart system:
<?php
session_start();
require_once 'conn.php';
$_SESSION['id'] = $_GET['id'];
$result_pedido = "SELECT * FROM tb_produtos WHERE p_id = '{$_SESSION['id']}'";
$resultado_pedido = mysqli_query($conn, $result_pedido);
$pedidos = mysqli_fetch_all($resultado_pedido, MYSQLI_ASSOC);
?>
Here I can only add one product and, I can't save it into a $_SESSION, having said that the product disapears once iI leave the cart.
<?php foreach($pedidos as $pedidos):?>
<tr>
<td>
<div class="cart-img">
<img src="uploads/<?php echo $pedidos['imagem'];?>" width="125px">
</div>
</td>
<td>
<div class="cart-model">
<?php echo $pedidos['pnome'] ; ?>
</div>
</td>
<td>
<div class="cart-quantity">
<input class="i-quantity" type="number" value="1">
</div>
</td>
<td>
<div class="cart-price">
R$<?php echo $pedidos['preço'] ; ?>
</div>
</td>
</tr>
</tbody>
</table>
<?php endforeach; ?>

Answer 1

If you check this line:
$_SESSION['id'] = $_GET['id'];
This mean the "id" in your $_SESSION is always set to $_GET['id'], even if it is empty. So it is reset every time the user visit a page.
You should:
have some mechanism to store your shopping cart content. There is none in your code; and
have a way to check if the user visits a new id before storing it to shopping cart.
For example,
<?php
/**
* This only make sense if this script is called
* by some AJAX / javascript interaction to specifically
* add a new item to cart.
*/
session_start();
require_once 'conn.php';
if (isset($_GET['id']) && !empty($_GET['id'])) {
$_SESSION['id'] = $_GET['id'];
}
$result_pedido = "SELECT * FROM tb_produtos WHERE p_id = '{$_SESSION['id']}'";
$resultado_pedido = mysqli_query($conn, $result_pedido);
$pedidos = mysqli_fetch_all($resultado_pedido, MYSQLI_ASSOC);
// If the user visits a path where the $_GET['id'] have result in
// database and the user specified that he / she want to save something
// to his / her cart.
if (isset($_GET['id']) && !empty($_GET['id']) && !empty($pedidos)) {
if (!isset($_SESSION['cart'])) $_SESSION['cart'] = []; // initialize if not exists.
$_SESSION['cart'] = array_merge($_SESSION['cart'], $pedidos);
}
?>
Note: the quantity should be set to the cart somehow. You need to change the data structure to set or increment the "qty". But this is at least a start.