Auto Expire/Delete Custom Post Type Posts after specified time

Question

I know there are plugins for this but none allow me do expire them automatically without manually picking a date inside of the post. I have many users who post to different CPT's and I want to delete them within 12 hours (or so) of being posted without the user manually setting it. I have been researching best ways to do this and have been trying to piece together different suggestions to accomplish my goal. I am hoping someone can point me in the right direction.

I know I am not there but I am also at a loss as to where to go from here. I appreciate any input you can give.

For this example I chose to just start with a specific custom pout type for simplicity.

To start I built a WP-Cron Job based off of https://www.elegantthemes.com/blog/tips-tricks/how-to-add-cron-jobs-to-wordpress

functions.php

add_action('wp','alerts_cron');

function alerts_cron(){
    if(!wp_next_scheduled('hpsts_alerts_cron')){
        wp_schedule_event_time(time(), 'hourly', 'hpsts_alerts_cron');
    }
}

Next My action function, I used this post as a starting point

add_action('hpsts_alerts_cron','expire_cpt_alert');
function expire_cpt_alert(){
    $args =  array (
        'post_type' => 'hp_dual_credit',
        'post_status' => 'publish'
    );

    $expire_query = new WP_Query($args);

    if($expire_query->have_posts()) {

        while($expiry_query->have_posts()) : $expire_query->the_post();

        //This is where I start to get lost, I know I want to expire after 12 hours however if my Cron runs hourly I could test better if this was  

        $publish_time = get_the_time('U');
        $delete_time = $publish_time + 3600;
        $current_time = date('H');

        if($current_time >= $delete_time){
            wp_delete_post(get_the_ID(), true);
        }

        endwhile;
    }
}

Answer 1

Ok, so it looks like you're having a problem with the publish time being a unix timestamp, but your current time is not, it's just returning the hours.

$publish_time = get_the_time('U'); // Returns our $publish time as a Unix timestamp
$delete_time = $publish_time + 43200; // 60 sec * 60 min * 12 hrs = 43,200 sec
$current_time = time(); // time is a the current time in a Unix timestamp

if ( $current_time >= $delete_time ) {
    wp_delete_post(get_the_ID(), true);
}