PHP 会话和 session_start() [英] PHP sessions and session_start()

问题描述

抱歉，如果这是一个愚蠢的问题，但最近我一直在为客户设计一个网站，并且在我的会话中发生了一些奇怪的事情.

Sorry if this is a silly question but lately I've been designing a site for a client and something strange has been happening with my sessions.

该网站有一个 PayPal 按钮，可将用户重定向到 PayPal，以便他们在再次重定向到该网站之前确认付款.

The site has a PayPal button which redirects the user to PayPal so they can confirm a payment, before being redirected to the site again.

在重定向用户之前，会保存大量会话变量.其中一些与 PayPal 有关，其他与我网站上的内容有关，例如用于确定登录用户的变量、他们的购物车项目等.

Before the user is redirected, a load of session variables are saved. Some of them are to do with PayPal, others are to do with things on my site such as a variable to determine which user is logged in, their shopping cart items, etc.

现在，这里出现了问题......

Now, here's where things have been going wrong...

用户从 checkout.php 重定向到 PayPal.在它们被重定向之前，站点的所有会话变量都存在(由 var_dump 和 print_r 显示).这可以.

The user is redirected from checkout.php to PayPal. Before they're redirected, all session variables for the site are present (shown by var_dump and print_r). This is fine.

用户从 PayPal 返回到 orderreview.php，但 var_dump 和 print_r 现在显示站点会话变量丢失，但所有 PayPal 变量都存在.

The user returns from PayPal to orderreview.php, but var_dump and print_r now show that the site session variables are missing, but all PayPal ones are there.

我通过删除session_start();"解决了这个问题来自 orderreview.php 的顶部.

I fixed this problem by removing "session_start();" from the top of orderreview.php.

所以我的问题是，为什么删除该行可以解决问题?为什么以前不行?

So my question is, why did removing that line fix the issue? Why wouldn't it work before?

我以为我了解 PHP 会话，但显然我并不像我想象的那样了解它们.

I thought I understood PHP sessions but clearly I don't understand them as well as I thought.

我曾在某处读到过:

从 PHP 4.3.3 开始，在会话已经启动时调用 session_start() 将导致级别 E_NOTICE 的错误.此外，第二个会话启动将被忽略."

"As of PHP 4.3.3, calling session_start() while the session has already been started will result in an error of level E_NOTICE. Also, the second session start will simply be ignored."

所以我假设如果会话已经提前启动，在脚本顶部调用 session_start 不会影响任何事情.

So I was under the assumption that calling session_start at the top of the script wouldn't affect anything if a session was already started earlier.

感谢您的回答，如果这是一个愚蠢的问题，我再次道歉.

Thanks for any answers, once again I apologise if this is a silly question.

推荐答案

那可能是因为您在此过程中被重定向到另一个站点.当您从 Paypal 返回到您的网站时，session_start() 生成了一个新的会话 ID，您之前存储的会话变量未链接到该 ID.

That's may be because that you have been redirected to another site during the process. And while you return from Paypal to your website, session_start() generated a new session id which your previously stored session variables are not linked to.

当您删除 session_start() 时(我认为 session 应该在没有这个的情况下工作)，它使用旧的 session id 并且从未重新生成.因此，旧的会话数据又回来了！

And when you removed session_start() (I don't think session should work without this on top), it used the old session id and never got regenerated. Hence, old session data are back!

这只是我的假设.

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