php - php 无法读取会话值

Question

我正在使用 login.php 页面。当用户登录成功时，系统会将他们的用户名保存到会话中。如下代码：

if ($user != null) {
    $_SESSION['username'] = $user["username"];
    $_SESSION['userid'] = $user["id"];
    return 0;
}

然后页面将位于 main.php。Main.php 将读取会话，如下面的代码：

session_start();
if (isset($_SESSION['username']) == false || empty($_SESSION['username']))
{
    // transfer into login page
}
else
{
    echo $_SESSION['username'];
}

主页无法读取 $_SESSION['username']，值为 null。我现在该怎么办？

Answer 1

您应该session_start()在$user检查条件页面添加。

session_start();
if ($user != null)
{
    $_SESSION['username'] = $user["username"];
    $_SESSION['userid'] = $user["id"];
    return 0;
} 

Answer 2

session_start()使用 SESSION 变量时必须添加

session_start(); //at the beginning of file 

if ($user != null) {
    $_SESSION['username'] = $user['username'];
    $_SESSION['userid'] = $user['id'];
    return 0;
} 

进而

session_start();

if (isset($_SESSION['username'])) {
    // transfer into login page
}
else
{
    echo $_SESSION['username'];
}

Answer 3

如果您想使用会话变量。您必须在使用会话变量之前启动会话。

session_start();
if ($user != null) {
    $_SESSION['username'] = $user["username"];
    $_SESSION['userid'] = $user["id"];
    return 0;
}

Answer 4

session_start();
if (count($user)>0 and is_array($user)) {
    $_SESSION['username'] = $user["username"];
    $_SESSION['userid'] = $user["id"];

}