Making post pagination in wordpress works dynamically from php - php

Question

I creating a small plugin to add <!--nextpage--> shortcode under some requirements.
For example , my plugin will check if the user agent is a bot, if yes it will not add <!--nextpage--> and if not it will add it.
What I achieved so far is I created a function to check user agent :
function test(){
if($_SERVER['HTTP_USER_AGENT'] == ' Bot i want '){
// here we dnt show <!--nextpage-->
} else {
do_shortcode('<!--nextpage-->');
}
}
add_shortcode('myshortcode','test');
So when I add the short code in the post editor it work fine, but the only problem is it doesn't add the <!--nextpage-->, it doesn't get executed, and if I try other short codes like [tweetme] or other registred short codes they work just fine.

Answer 1

To print out into your html page, you shouldn't not call
do_shortcode('<!--nextpage-->');
The above line will do nothing, since is not a valid shortcode format in Wordpress, and as a result, do_shortcode cannot parse it.
A valid shortcode in wordpress need to be wrapped with [ ] brackets.
To achieve what you are trying to do (printing out '' when web crawler detected), you can just change your test function to:
function test(){
if($_SERVER['HTTP_USER_AGENT'] == ' Bot i want '){
// here we dnt show <!--nextpage-->
} else {
echo '<!--nextpage-->';
}
}
Also, you can have a look at do_shortcode function documentation here: https://developer.wordpress.org/reference/functions/do_shortcode/