Acessing $_SESSION in PHP - php

Question

I'm creating an Inventory system in PHP
foreach ($_SESSION["cart_array"] as $each_item) {
$item_id = $each_item['item_id'];
$sql = mysqli_query($mysqli, "SELECT * FROM booklists WHERE book_id='$item_id' LIMIT 1");
while ($row = mysqli_fetch_array($sql)) {
$product_name = $row["book_name"];
When I echo my $_SESSION using this
print_r($_SESSION["cart_array"]);
I added 2 item in the cart with the quantity of 1 and 55
Array (
[0] => Array ( [item_id] => 37 [quantity] => 1 )
[1] => Array ( [item_id] => 32 [quantity] => 55 )
)
I wanna update all of the [quantity] values in my session. how do you think I can achieve it ?

Answer 1

The question isn't overly clear, as I don't know what the quantity needs updating by, but to update each quantity, you could do something like this.
foreach($_SESSION['cart_array'] as $index => $item){
// Add 1 to each quantity
$_SESSION['cart_array'][$index]['quantity']++;
}
// Or...
$increaseBy = 5;
foreach($_SESSION['cart_array'] as $index => $item){
// Increase by a fixed amount.
$_SESSION['cart_array'][$index]['quantity'] += $increaseBy;
}
// Or...
foreach($_SESSION['cart_array'] as $index => $item){
// Increase by a random number between 5 and 15.
$_SESSION['cart_array'][$index]['quantity'] += rand(5, 15);
}
// Or...
foreach($_SESSION['cart_array'] as $index => $item){
$increaseBy = $this->getQuantityIncrease($item['item_id']);
$_SESSION['cart_array'][$index]['quantity'] += $increaseBy;
}
// Or...
// By using references.
foreach($_SESSION['cart_array'] as $index => &$item){
$increaseBy = $this->getQuantityIncrease($item['item_id']);
$item['quantity'] += $increaseBy;
}

Answer 2

You can try something like this in your loop,
foreach ($_SESSION["cart_array"] as $key => $item) {
$_SESSION['cart_array'][$key]['quantity'] = 13; // set the qty you want
}

Answer 3

You can use a foreach loop to do this.
$newQuantityValue = 10;
foreach($_SESSION['cart_array'] as $key => $value){
$_SESSION[$key]['quantity'] = $newQuantityValue;
}
All we do here is assign a new value for our quantity and then use a foreach loop to iterate through the $_SESSION variable so that we can update each of your quantity fields with our new value (in this case 10).
For more information about foreach loops, check out the the PHP Docs
Pass By Reference:
You could equally change the value by passing it by reference like this:
$newQuantityValue = 10;
foreach($_SESSION['cart_array'] as $key => &$value){
$value['quantity'] = $newQuantityValue;
}
Because we are passing it by reference, there is no longer any need to reference the $_SESSION
From the docs:
In order to be able to directly modify array elements within the loop precede $value with &. In that case the value will be assigned by reference.
As a side note:
You could dispense with the $newQuantityValue variable all together and instead just put the number into the loop like this:
foreach($_SESSION['cart_array'] as $key => $value){
$_SESSION[$key]['quantity'] = 10;
}