How do i update an array within a cookie? - php

Question

I'm saving a cart array within a cookie, to send it to the shopping cart page. Whenever i go to a page from another product and click on add to cart it doesn't add it to the array, but seems to overwrite it.
$uri = $_SERVER['REQUEST_URI'];
$pin = explode('/', $uri);
$id = $pin[3];
$product = $model->selectById($id, 'carpet');
$product = $product->fetch(PDO::FETCH_ASSOC);
$site_url = site_url();
if(!$product){
header("Location: $site_url./404");
}
if(isset($_POST['add'])){
$cart = [];
$cart[$product['id']] = [];
$cart[$product['id']]['product_name'] = $product['name'];
setcookie('cart', serialize($cart), time()+3600);
$cart = unserialize($_COOKIE['cart']);
dd($cart);
}

Answer 1

You have given the answer already: you are overwriting the cart each time this script runs. Changes:
$uri = $_SERVER['REQUEST_URI'];
$pin = explode('/', $uri);
$id = $pin[3];
$product = $model->selectById($id, 'carpet');
$product = $product->fetch(PDO::FETCH_ASSOC);
$site_url = site_url();
if(!$product){
header("Location: $site_url./404");
}
if(isset($_POST['add'])){
if ( isset($_COOKIE['cart']) )
$cart = unserialize($_COOKIE['cart']); // if cookie is set, get the contents of it
else
$cart = []; // else create an empty cart
// append new product and add to cart
$cart[$product['id']] = [];
$cart[$product['id']]['product_name'] = $product['name'];
setcookie('cart', serialize($cart), time()+3600);
$cart = unserialize($_COOKIE['cart']);
dd($cart);
}

Answer 2

2nd part of the question: How to increase order quantity of a product:
...
// is this product alread in cart?
if ( isset($cart[$product['id']])
$prod = $cart[$product['id']]; // then pick it
else
{
// create a new product object
$prod = new stdClass();
// initialze with name and zer quantity
$prod->name = $product['name'];
$prod->quantity = 0;
}
// increment quantity
$prod->quantity ++;
// reassign to array
$cart[$product['id']] = $prod;
...