How to skip certain links on adjacent posts in Wordpress? - php

Question

I use the following code to fetch the links of the previous and next posts respectively, from the single post template;
<?php echo get_permalink(get_adjacent_post(false,'',false)); ?>
<?php echo get_permalink(get_adjacent_post(false,'',true)); ?>
My question is, please, if there are certain posts I'd like these codes to skip, and simply go to the ones right after, could I do that somehow using custom fields, or otherwise how can I make Wordpress skip a certain link when it comes up and fetch the next adjacent one without first going to the one I'd like to skip and then redirect or something, but rather echo the correct one right away..?
Thank you very much!
Alex

Answer 1

You can approach this in different ways. The easiest solution would probably be to use an "excluded category" (second parameter), e.g. exclude posts from category with term ID 5:
get_adjacent_post( false, '5', false )
Another option is to use the get_previous_post_where and get_next_post_where filters to modify the SQL query.
You could store in the options table an array of post IDs to be excluded, here's an example how you could exclude all sticky posts:
add_filter( 'get_previous_post_where', 'so16495117_mod_adjacent' );
add_filter( 'get_next_post_where', 'so16495117_mod_adjacent' );
function so16495117_mod_adjacent( $where ) {
return $where . ' AND p.ID NOT IN (' . implode( ',', get_option( 'sticky_posts' ) ) . ' )';
}
Or, as you suggested in your Q, you could filter out posts that have a certain post meta key, e.g. my_field:
add_filter( 'get_previous_post_where', 'so16495117_mod_adjacent_bis' );
add_filter( 'get_next_post_where', 'so16495117_mod_adjacent_bis' );
function so16495117_mod_adjacent_bis( $where ) {
global $wpdb;
return $where . " AND p.ID NOT IN ( SELECT post_id FROM $wpdb->postmeta WHERE ($wpdb->postmeta.post_id = p.ID ) AND $wpdb->postmeta.meta_key = 'my_field' )";
}