PHP逻辑运算符组合

Question

I am using some PHP to redirect a website visitor if they are not logged in using the CMS's members addon. I have this code which is working fine:

if (!perch_member_logged_in() && ($_SERVER["REQUEST_URI"] !== '/')){
  PerchSystem::redirect('/');
}

I now want to add a query string to see if someone has been redirected, and display an appropriate message. I don't want to display this if someone comes directly to the home page. I tried this:

if (!perch_member_logged_in() && (($_SERVER["REQUEST_URI"] !== '/') || ($_SERVER["REQUEST_URI"] !== '/?redirect=true'))){
  PerchSystem::redirect('/?redirect=true');
}

But I am getting too many redirects. Can anyone help with this?

Answer 1

I think you just need this:

if (!perch_member_logged_in() && $_SERVER["REQUEST_URI"] !== '/?redirect=true') {
  PerchSystem::redirect('/?redirect=true');
}

If the user is not logged in and comes to your page, he can land on one of three pages:

• home page - do nothing
• home page with redirect=true set - also do nothing
• any other page - redirect to homepage with redirect=true

Answer 2

To start with I'd like to point you to the Operator Precedence page in the PHP manual. It explains in which order the operators are evaluated, which should help you get rid of some of the unnecessary parenthesis in your code.
I suspect that this might solve your problem as well, depending upon what you mean with "too many redirects."

Though, I suspect that you don't need to check for redirection upon root access as well. Hard to say for certain, as you haven't properly explained what your problem is, and what you expect to happen.
In other words, I (too) think your code should look like this:

if (!perch_member_logged_in() && $_SERVER["REQUEST_URI"] !== '/?redirect=true'){
    PerchSystem::redirect('/?redirect=true');
}

As that bit of code says: If the user is not logged in, and the redirect flag is set, redirect the user.

Another thing you should do, is to check the code in the PerchSystem::redirect() method, and make sure it uses die() after sending the Location header. Otherwise your code will continue to execute, and cause unwanted behavior and/or security issues.

Answer 3

Turns out I needed this:

if (!perch_member_logged_in() && ($_SERVER["REQUEST_URI"] !== '/') && ($_SERVER["REQUEST_URI"] !== '/?redirect=true')){
  PerchSystem::redirect('/?redirect=true');
}

Thanks everyone who took the time to respond I appreciate it