将数量添加到购物篮中将添加一个新商品

Question

I am creating a basket and what I want is if an item that is already in the basket is added again, the quantity of the original item will be appended by 1.

Instead when I add an item that is already in the basket, a new item is added, and the quantity of this new item can be appended by clicking +1 on the original item.

basket.php

<?php
  foreach ($_SESSION["basket"] as $basketItemArray) {                   
?>

<form role="form" action="includes/functions/create_shopping_cart.php" method="post">
    <button type="submit" name="basket-button" class="btn btn-default" value="<?php echo $basketItemArray["item_id"]; ?>"><i class="fa fa-plus" aria-hidden="true"></i></button>
    <? echo $basketItemArray["quantity"]; ?>
    <button class="btn btn-default"><i class="fa fa-minus" aria-hidden="true"></i></button>
</form>

The above form sends the item_id through the value of the + button.

create_shopping_cart.php

$product_id = $_POST['basket-button'];
$sql = "SELECT * FROM menu WHERE product_id='".$product_id."'";

$result = $connection->query($sql);
$row = $result->fetch_assoc();

if (empty($_SESSION["basket"])) {
    $_SESSION["basket"]  = array( 

    array( "item_id"=>$row['product_id'], "item_name"=>$row['name'],"quantity"=>1 , "price"=>$row['price']) );

} else {
    // There is already a basket to append to
    $current_basket = $_SESSION["basket"];

    $found = false;
    foreach($_SESSION['basket'] as $product)
    {
        if($product_id == $product['item_id']) {
            $found = true;
            break;
        }
    }

    if($found)
    {
        $_SESSION['basket'][$product_id]['quantity'] ++;               
    } else {
        $new_basket  = array( 

        array( "item_id"=>$row['product_id'], "item_name"=>$row['name'],"quantity"=>1 , "price"=>$row['price']) );

        $_SESSION['basket'] = array_merge($current_basket, $new_basket);      
    } 
}

Result

Answer 1

You are not targeting/using the index of the products in basket. Try this:

$product_id = $_POST['basket-button'];
$sql = "SELECT * FROM menu WHERE product_id='".$product_id."'";

$result = $connection->query($sql);
$row = $result->fetch_assoc();

if (empty($_SESSION["basket"])) {
    $_SESSION["basket"]  = array( 

    array( "item_id"=>$row['product_id'], "item_name"=>$row['name'],"quantity"=>1 , "price"=>$row['price']) );

} else {
    // There is already a basket to append to
    $current_basket = $_SESSION["basket"];

    $found = false;
    $id = '';
    foreach($_SESSION['basket'] as $key=>$product)
    {
        if($product_id == $product['item_id']) {
            $found = true;
            $id    = $key;
            break;
        }
    }

    if($found)
    {
        $_SESSION['basket'][$id]['quantity']++;               
    } else {
        $new_basket  = array( 

        array( "item_id"=>$row['product_id'], "item_name"=>$row['name'],"quantity"=>1 , "price"=>$row['price']) );

        $_SESSION['basket'] = array_merge($current_basket, $new_basket);      
    } 
}

Your code can be optimized some more but for now it is more important to get it to work correctly.