thinkphp still has a problem with jumping to the pre-login page after logging in

I previously wanted to implement this in the background. Yesterday I asked a question about the link description here, but no one answered. I felt that the background implementation was a bit complicated. Then I wanted to implement the function of jumping after login in the front desk.
I am in the login template I made the following judgment. If there is a session, let it return to the previous page. When judging whether there is a session in the action, I only wrote that there is no session and then let it display() if there is no session. If there is, it will not be processed. I am just afraid. I can't jump to the previous page, so I didn't write it, but it still can't jump. I never thought that the problem of login jump is so complicated. I don't know if you guys have a good way. I searched all over the Internet and there is no good and complete example. Can everyone help me

public function login(){ $user=M('user'); $name=I('name'); $pw=I('pw'); $res=$user->where("username='$name' AND password='$pw'")->select(); if($res){ session('res2',$res); } if(!isset(session('res2')[0])){ $this->display();//如果没有session则显示login页面 } }

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I previously wanted to implement this in the background. Yesterday I asked a question about the link description here, but no one answered. I felt that the background implementation was a bit complicated. Then I wanted to implement the function of jumping after login in the front desk.
I am in the login template I made the following judgment. If there is a session, let it return to the previous page. When judging whether there is a session in the action, I only wrote that there is no session and then let it display() if there is no session. If there is, it will not be processed. I am just afraid. I can't jump to the previous page, so I didn't write it, but it still can't jump. I never thought that the problem of login jump is so complicated. I don't know if you guys have a good way. I searched all over the Internet and there is no good and complete example. Can everyone help me

public function login(){ $user=M('user'); $name=I('name'); $pw=I('pw'); $res=$user->where("username='$name' AND password='$pw'")->select(); if($res){ session('res2',$res); } if(!isset(session('res2')[0])){ $this->display();//如果没有session则显示login页面 } }

$_SERVER['HTTP_REFFERER']

Just try history.go(-1)

Let’s put it this way, the problem of detecting login and permissions should be written in the parent class, and then let each controller inherit it.
Then judge
session(!$args)
Then redirct is roughly like this
As for the jump, you can read more about this self document, it should not be difficult.
Or you can also use session.