【发布时间】：2017-04-10 08:36:59
【问题描述】：
我正在构建一个学习计划器，在登录后只有一个欢迎区域。我目前正在尝试获取当前登录用户的用户 ID，以便在此欢迎区域的 SQL 更新查询中使用作为用户在欢迎消息中使用的名字。
我尝试将$_SESSION['user_id'] = userid; 和$_SESSION['user_firstname'] = firstname; 放在$_SESSION['login_user'] = $username; 之后($_SESSION['login_user'] = $username; 工作正常）但是在登录页面时，我收到这些错误：Notice: Use of undefined constant userid - assumed 'userid' in C:\wamp64\www\justread\session.php on line 11 和Notice: Use of undefined constant firstname - assumed 'firstname' in C:\wamp64\www\justread\session.php on line 12。
现在，我知道错误要我先对“userid”和“firstname”进行某种初始化，然后再使用它们来设置会话变量，但我不知道该怎么做，所以我想知道如果有人可以帮助我，请。
提前谢谢你。
如果需要，我可以发布更多代码，但我认为相关的代码是：
login.php：
<?php
// Start session
session_start();
// Variable to store error message
$error ="";
// If the login form (Note that the 'submit' refers to the 'name' attribute of the login form) has been submitted...
if (isset($_POST['submit'])) {
// If username or password is not provided...
if (empty($_POST['username']) || empty($_POST['password'])) {
// ...tell user that login details are invalid.
$error = "Please fill in both your username and your password";
// Else...
} else {
// ...put the provided username and password in variables $username and $password, respectively
$username = $_POST['username'];
$password = $_POST['password'];
// Establish connection to the server
$mysqli = mysqli_connect("localhost", "root", "");
// set up measures to counter potential MySQL injections
$username = stripslashes($username);
$password = stripslashes($password);
$username = mysqli_real_escape_string($mysqli, $username);
$password = mysqli_real_escape_string($mysqli, $password);
// Select Database
$db = mysqli_select_db($mysqli, "p00702");
// SQL query to fetch information of registerd users and find user match.
$query = mysqli_query($mysqli, "SELECT * from logins WHERE password='$password' AND username='$username'");
// Return the number of rows of the query result and put it in $rows variable
$rows = mysqli_num_rows($query);
// If rows are equal to one...
if ($rows == 1) {
unset($_SESSION['error']);
// Initialize session with the username of the user...
$_SESSION['login_user'] = $username;
// Set the user ID of the user
$_SESSION['user_id'] = userid;
// Set the user first name of the user
$_SESSION['user_firstname'] = firstname;
// ...and redirect to the homepage.
header("Location: welcome.php");
// Make sure that codes below do not execut upon redirection.
exit;
// Else,
} else {
// and tell user that the login credentials are invalid.
$error = "Your username or password is invalid";
$_SESSION['error'] = $error;
// redirect user to the home page (index.php)
header("Location: index.php");
}
// ...and close connection
mysqli_close($mysqli);
}
}
session.php
<?php
// Establish connection to the server
$mysqli = mysqli_connect("localhost", "root", "");
// Selecting Database
$db = mysqli_select_db($mysqli, "p00702");
// Starting session
session_start();
// Storing Session
$user_check = $_SESSION['login_user'];
$_SESSION['user_id'] = userid;
$_SESSION['user_firstname'] = firstname;
// Test to see the content of the global session variable
print_r($_SESSION);
// SQL Query To Fetch Complete Information Of User
$ses_sql = mysqli_query($mysqli, "SELECT username FROM logins WHERE username='$user_check'");
$row = mysqli_fetch_assoc($ses_sql);
$login_session = $row['username'];
if (!isset($login_session)) {
// Closing Connection
mysqli_close($mysqli);
// Redirecting To Home Page
header('Location: index.php');
// Make sure that codes below do not execut upon redirection.
exit;
}
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