PHPを使用してWeChatアプレットのテイクアウト注文機能を実装するにはどうすればよいですか?

<?php

$code = $_GET['code']; // 从请求参数中获取code

// 发送请求到微信服务器，换取openid和session_key
$appid = 'YOUR_APPID';
$secret = 'YOUR_SECRET';
$grant_type = 'authorization_code';

$url = "https://api.weixin.qq.com/sns/jscode2session?appid=$appid&secret=$secret&js_code=$code&grant_type=$grant_type";

$response = file_get_contents($url); // 发送请求

$data = json_decode($response, true); // 解析返回结果

$openid = $data['openid']; // 获取openid
$session_key = $data['session_key']; // 获取session_key

// 将openid和session_key保存到服务器端，用于后续的业务逻辑

?>

<?php

// 连接数据库（假设使用MySQL）
$servername = "localhost";
$username = "YOUR_USERNAME";
$password = "YOUR_PASSWORD";
$dbname = "YOUR_DBNAME";

$conn = new mysqli($servername, $username, $password, $dbname);
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

// 查询菜单数据
$sql = "SELECT * FROM menu";
$result = $conn->query($sql);

$menus = array(); // 用于保存所有菜单数据

if ($result->num_rows > 0) {
    while ($row = $result->fetch_assoc()) {
        $menu = array(
            "id" => $row["id"],
            "name" => $row["name"],
            "price" => $row["price"],
            "image" => $row["image"]
        );

        array_push($menus, $menu);
    }
}

$conn->close();

// 将菜单数据以JSON格式返回给小程序
echo json_encode($menus);

?>

<?php

// 获取用户提交的订单数据
$openid = $_POST['openid']; // 用户openid
$items = json_decode($_POST['items'], true); // 订单菜品列表
$total = $_POST['total']; // 订单总金额

// 将订单数据保存到数据库
$servername = "localhost";
$username = "YOUR_USERNAME";
$password = "YOUR_PASSWORD";
$dbname = "YOUR_DBNAME";

$conn = new mysqli($servername, $username, $password, $dbname);
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

$sql = "INSERT INTO orders (openid, items, total) VALUES ('$openid', '$items', '$total')";

if ($conn->query($sql) === TRUE) {
    echo "订单保存成功";
} else {
    echo "Error: " . $sql . "<br>" . $conn->error;
}

$conn->close();

// 处理订单完毕，可以发送通知给用户等

?>