javascript - 限制用户在php中多次添加一件商品到购物车

Question

我用 php 创建了一个网站。我在其中提供了购物车功能。当用户单击“添加到购物车”按钮时，他们应该被重定向到显示商品的购物车页面。处理购物车代码的library.php如下:

<?php

// load database connection script

include("database_connection.php");

/*
 * Tutorial: PHP MySQL Shopping cart
 *
 * Page: Application library
 * */

class ShopingCart
{



    protected $db;

    function __construct()
    {
        $this->db = DB();
    }

    /**
     * get products list
     *
     * @return array
     */
    public function getProducts()
    {
        $query = "SELECT *  FROM `entertainment`";
        if (!$result = mysqli_query($this->db, $query)) {
            exit(mysqli_error($this->db));
        }
        $data = [];
        if (mysqli_num_rows($result) > 0) {
            while ($row = mysqli_fetch_assoc($result)) {
                $data[] = $row;
            }
        }

        return $data;
    }

    /**
        * get given product details
        *
        * @param [integer] $id
        * @return array
        */
       public function getProductDetails($id)
       {
           $id = mysqli_real_escape_string($this->db, $id);
           $query = "SELECT *  FROM `entertainment` WHERE `id` = '$id'";
           if (!$result = mysqli_query($this->db, $query)) {
               exit(mysqli_error($this->db));
           }
           $data = [];
           if (mysqli_num_rows($result) > 0) {
               while ($row = mysqli_fetch_assoc($result)) {
                   $data['id'] = $row['id'];
                   $data['title'] = $row['title'];
                   $data['price'] = $row['vendor_price'];
                   $data['quantity'] = 1;
               }
           }

           return $data;
       }

       /**
        * Add new product into the cart
        *
        * @param [integer] $id
        * @return void
        */
       public function addToCart($id)
       {

         $product = $this->getProductDetails($id);

         $isFound = false;
         $i = 0;

         if (!isset($_SESSION['shopping_cart']) || count($_SESSION['shopping_cart']) < 1)
         {
             $_SESSION['shopping_cart'] = array(0 => $product);
         } else {

             foreach ($_SESSION['shopping_cart'] as $item) {
                 $i++;
                 foreach ($item as $key => $value) {
                     if ($key == "id" && $value == $id) {
                         array_splice($_SESSION['shopping_cart'], $i - 1, 1, array([
                             'id' => $item['id'],
                             'title' => $item['title'],
                             'price' => $item['vendor_price'],
                             'quantity' => $item['quantity'] + 1,
                         ]));
                         $isFound = true;
                     }
                 }

             }
             if ($isFound == false) {
                 array_push($_SESSION['shopping_cart'], $product);
             }
         }

       }

       /**
        * remove existing product from the cart
        *
        * @param [integer] $id
        * @return void
        */
       public function removeProductFromCart($id)
       {
           unset($_SESSION['shopping_cart'][$id - 1]);
       }


}

?>

我的购物车 php 文件如下所示:

<?php
                    if(isset($_SESSION['shopping_cart']) && count($_SESSION['shopping_cart']) > 0)
                    {
                        $entertainment = $_SESSION['shopping_cart'];

                        echo '
                                <table class="table table-hover table-bordered">
                                <thead>
                                    <tr>
                                    <th scope="col">#</th>
                                    <th scope="col">Title</th>
                                    <th scope="col">Quantity</th>
                                    <th scope="col">Price</th>
                                    <th scope="col" width="100">Action</th>
                                    </tr>
                                </thead>';

                        $item_number = 1;
                        $total = 0;
                        foreach ($entertainment as $product) {
                        echo '
                                <tbody>
                                    <tr>
                                    <th scope="row">'. $item_number .'</th>
                                    <td>' . $product['title'] . '</td>
                                    <td>'.$product['quantity'].'</td>
                                    <td>₹ '. $product['price']. '</td>
                                    <td>
                                        <a href="cart.php?id_to_remove=' . $item_number . '" class="btn btn-danger btn-sm">X</a>
                                    </td>
                                    </tr>
                                </tbody>
                           ';
                           $total += ((int)$product['price'] * $product['quantity']);
                            $item_number++;
                        }

                        echo '
                                <tr>
                                    <th colspan="4" align="right">
                                        Total:
                                    </th>
                                    <td>
                                        ₹ '. $total .'
                                    </td>
                                </tr>
                                </table>';

                    }

其实这个购物车是我引用网上资料制作的。购物车工作正常。但问题是我需要限制用户多次添加一个项目，用户只能添加一个项目一次，即该项目的数量应该只有1，当用户尝试多次添加一个项目时，他们应该引起警惕。

谁能告诉我如何解决这个问题？

Answer 1

您可以通过添加以下内容来消除值数组中的重复值:

array_unique($yourArray);

如果您的数组具有这些值:

$yourArray = ['a','b','c','b'];
$array = array_unique($yourArray);
//$array = ['a','b','c'];