Check if user is logged in when clicking certain links on certain pages

Question

On my site I have a number of post category archive pages. What I would like to do is set it up so that when links to specific posts are clicked on these pages the user is sent to the post only if they are logged in. Otherwise they would be sent to the login/sign up page.

I don't want the articles themselves to be restricted, meaning if somebody found a link outside my site to the post they would be able to view it without logging in. I only want access restricted when the user is coming directly from an internal archive page.

Thank you for your help.

Answer 1

You might start by looking at the is_user_logged_in() pluggable function.

https://developer.wordpress.org/reference/functions/is_user_logged_in/

This is basically two lines:

$user = wp_get_current_user();
return $user->exists();

In your case, wrap the links inside the curly braces of a conditional.

if ( is_user_logged_in() ) {

    // link
}

Answer 2

I've worked it out with thanks to LPH for pointing me in the right direction.

I added this to functions.php:

function login_page_url() {
    global $loginurl;
    $loginurl = "login page url";
    echo $loginurl;
}

And this to category.php, where the link to the post goes:

<a href="<?php if ( is_user_logged_in() ) { echo get_permalink(); } else { echo login_page_url(); } ?>">