Question

I want write function which add to my post content <!--nextpage--> tags, I write this function:

<?php
function output($content) {
$output = $content.'<!--nextpage-->'.$content;

return $output;
}

add_filter('the_content','output');

?>

Function add <!--nextpage--> tags, but this tags not works when I display posts, it are like html comments, maybe are some solution to solve this problem ?

Maybe I must use not the_content but wp_insert_post_data ?

Answer 1

The conversion from text with <!--nextpage--> into “pages” happens in setup_postdata. But the hook you use executes when the template tag with the same name, the_content is called. So what this means is you have to change the content before the loop starts. It can be a bit tricky. Off the top of my head I don’t know of any suitable hooks but you can check the source code for setup_postdata and there might be one. In the theme, though, you can access $posts so if you put this in a template, it should work:

global $posts;
array_map( function( $apost ) {
    $apost->post_content = $apost->post_content.'<!--nextpage-->'.$apost->post_content;
    return $apost;
}, $posts );

If you don’t have PHP version => 5.3 you can’t use anonymous functions. In that case, this version will work:

global $posts;
function output( $apost ) {
    $apost->post_content = $apost->post_content.'<!--nextpage-->'.$apost->post_content;
    return $apost;
}
array_map( 'output', $posts );