How to use ThinkPHP to implement a shopping cart function

First, we need to create a database to store our products and order information. Copy and paste the following SQL code into phpMyAdmin or other MySQL client to create the database:

CREATE DATABASE cart DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;

Then, We need to create two tables to store product and order information. The following SQL statements create two tables: "products" and "orders": CREATE TABLE products ( product_id INT PRIMARY KEY, product_name VARCHAR(50), price DECIMAL(10,2) ); CREATE TABLE orders ( order_id INT PRIMARY KEY, product_id INT, order_date DATE, amount INT, FOREIGN KEY (product_id) REFERENCES products(product_id) );

CREATE TABLE products (
 id int(11) NOT NULL AUTO_INCREMENT,
 name varchar(255) NOT NULL,
 description text NOT NULL,
 price float NOT NULL,
 PRIMARY KEY (id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE orders (
 id int(11) NOT NULL AUTO_INCREMENT,
 user_id int(11) NOT NULL,
 product_id int(11) NOT NULL,
 quantity int(11) NOT NULL,
 created_at timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
 PRIMARY KEY (id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

Now, we need to set up our application. Use Composer to install the ThinkPHP framework:

composer create-project topthink/think tp5 --prefer-dist

Next, copy and paste the following code into the tp5/application/common.php file . The global helper function "getCart" will be created to obtain the user's shopping cart information

<?php
use app\index\model\Cart;
function getCart()
{
$user_id = 1; // 此处默认用户ID为1，实际应用中应该从会话中获取用户ID
$cart = Cart::where(&#39;user_id&#39;, $user_id)->select();
return $cart;
}

Next, we need to create a model named "Cart" to manage the items in the user's shopping cart.

<?php
namespace app\index\model;
use think\Model;
class Cart extends Model
{
protected $table = &#39;orders&#39;;

static function add($product_id, $quantity)
{
    $user_id = 1; // 此处默认用户ID为1，实际应用中应该从会话中获取用户ID
    $order = new Cart();
    $order->user_id = $user_id;
    $order->product_id = $product_id;
    $order->quantity = $quantity;
    $order->save();
}

static function remove($id)
{
    Cart::destroy($id);
}
}

We are now able to add or remove items from the shopping cart in the application by using the "Cart" model. Use the following code to add an item to the cart:

Cart::add($product_id, $quantity);

and the code to remove an item from the cart:

Cart::remove($id);

Finally, we need to create a controller called "Cart" and add two methods: one to display the cart contents and another to add items to the cart.

<?php
namespace app\index\controller;
use app\index\model\Cart;
class CartController extends BaseController
{
public function index()
{
    $cart = getCart();
    $this->assign(&#39;cart&#39;, $cart);
    return $this->fetch();
}

public function add()
{
    $product_id = input(&#39;post.product_id&#39;);
    $quantity = input(&#39;post.quantity&#39;);

    Cart::add($product_id, $quantity);

    $this->success(&#39;添加成功&#39;, url(&#39;index&#39;));
}
}

After completing the above steps, we have successfully created a simple shopping cart application. Now, we can display the contents of the shopping cart by accessing the index method of CartController, and add items to the shopping cart by accessing the add method of CartController.

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