How to compare values in a single foreach loop php - php

Question

I am working on opencart.I dont want to allow users to add same product multiple times in cart. for this i have a logic that i want to compare the products in cart. I will get the the product id of each product(how many the user added by clicking add to cart) than i will compare those ids. If they are same i will show them error message else they can carry on. For this logic i have used this code till now.
$products = $this->cart->getProducts();
foreach ($products as $product)
{
$p_id=$product['product_id'];
}
But i dont get that how will i compare 2 product ids in foreach loop. and than add my logic that if product ids are equal show error message.

Answer 1

You can simply check it at the time when user add a product to cart. To do so modify add function in controller->checkout->cart.php
In public function add() {
Add
$products = $this->cart->getProducts();
if($products){
foreach ($products as $product)
{
if($this->request->post['product_id'] == $product['product_id']){
$json['error']['blabla'] = 'Your warning message.';
break;
}
}
}
Before
if (!$json) {
And display that error wherever you want to display. That's it.

Answer 2

you can get the value of new product id and than compare it like this
//get product id to be added
$new_product = "get ID";
$products = $this->cart->getProducts();
foreach ($products as $product)
{
$p_id=$product['product_id'];
//compare with new product_id with existing
if ($_pid == $new_product){
echo " Product already exists!!";
}
}

Answer 3

$products = $this->cart->getProducts();
$exist = false;
foreach ($products as $product)
{
if ($p_id == $product['product_id']) {
$exist = true;
break;
}
}
if (!$exist) {
//add product co cart
}

Answer 4

Try this way
$products = $this->cart->getProducts();
$p_id = '';
foreach ($products as $product)
{
if($p_id != $product['product_id']) {
$p_id=$product['product_id'];
}else{
echo " Product already exists!!";
}
}

Answer 5

This will get you both a unique list of ID's and a list of ID's that needed to be removed to make the list unique.
// get the list of ID's
$products = $this->cart->getProducts();
$all = array();
foreach ($products as $product)
{
$all[] = $product['product_id'];
}
// Flip the array twice to just get the unique ID's
$unique = array_flip(array_flip($all));
// Get a list of ID's that were lost
$difference = array_diff_assoc($all, $unique);