Function to auto-delete wordpress media after period of time - php

Question

I'm writing what I thought was a simple series of functions to assign a "deletion date" to media, then auto-delete those expired media when the site is visited.
The post_meta for deletion date is set for the images via an online form when the images are uploaded (using formidable pro forms and the "after_create_entry" hook. I can confirm that the meta field is created successfully, and the deletion date is assigned properly (called 'mtp_deletiondate'. To test, I did a wp_query on a custom page and each image has a properly set deletion date.
Next, I wanted to run a function that checked for expired images (set to be 21 days after date of upload), and if they are expired, to delete them. I want to trigger this function whenever I access the admin, because I figure I get in there at least once a month to run updates, and it's a good time to clean out the old images. For this situation, I decided not to do a cron job since I can reliably visit the site once a month anyway.
The issue is the function doesn't seem to be triggering, and I don't know if it's because the function is broken or because I'm using the wrong action, or both. Some research tells me to use the admin_init, but I've also tried "wp", and "wp-footer". It might be that I'm just misunderstanding the process. My function (in my theme's functions.php):
function drick_delete_expired_uploads() {
// WP_Query arguments
$args = array (
'post_status' => 'any',
'post_type' => array( 'Attachment' ),
'posts_per_page' => -1,
'meta_query' => array(
array(
'key' => 'mtp_deletiondate',
),
),
);
// The Query
$mediaquery = new WP_Query( $args );
// The Loop
if ( $mediaquery->have_posts() ) {
while ( $mediaquery->have_posts() ) {
$mediaquery->the_post();
date_default_timezone_set('America/Denver');
$CurrentDate = date('Y-m-d h:i');
$CurrentDateStr = strtotime($CurrentDate);
$DeletionDate = get_post_meta( $post->ID, 'mtp_deletiondate', true );
$DeletionDateStr = strtotime($DeletionDate);
if ( isset($DeletionDateStr) ) {
if ( $DeletionDateStr < $CurrentDateStr ) {
wp_delete_attachment( $post->ID, true );
}
}
}
} else {
// no posts found
} // IF HAVE POSTS
// Restore original Post Data
wp_reset_postdata();
}
add_action('admin_init', 'drick_delete_expired_uploads');
If I save my functions.php, then reload the Wordpress dashboard, then check my media, the expired images are still there. HOWEVER, if I add this function to an actual page then visit the page, it does work. So I believe the function is doing what it's supposed to, it's just not getting triggered properly? I also added a quick wp_mail() to the function in my functions.php, and when I visited the admin it did trigger the email, so I guess the function is firing.
I would appreciate any insight, thank you!

Answer 1

So I think I figured it out, but I don't know that I have an explanation as to why it works. Essentially it looks like wp_delete_attachment wasn't working, but wp_delete_post DOES work. I've tested and confirmed with three additional images that the function auto delete is triggered when accessing the admin dashboard. I also changed the way the query arguments are structured by only querying the expired images, rather than querying ALL images that have a mtp_deletiondate meta then running a conditional statement within the query. Don't know if that's related or not. The final working function:
function drick_delete_expired_uploads() {
// WP_Query arguments
date_default_timezone_set('America/Denver');
$CurrentDate = date('Y-m-d h:i');
$args = array (
'post_status' => 'any',
'post_type' => array( 'Attachment' ),
'posts_per_page' => -1,
'meta_query' => array(
array(
'key' => 'mtp_deletiondate',
'value' => $CurrentDate,
'compare' => '<',
'type' => 'DATE',
),
),
);
// The Query
$mediaquery = new WP_Query( $args );
// The Loop
if ( $mediaquery->have_posts() ) {
while ( $mediaquery->have_posts() ) {
$mediaquery->the_post();
wp_delete_post(get_the_ID());
}
} else {
// no posts found
} // IF HAVE POSTS
// Restore original Post Data
wp_reset_postdata();
}
add_action('admin_init', 'drick_delete_expired_uploads');
Still look forward to any feedback from someone in the know that can tell me why the previous version wasn't working (looking to learn here). Thanks!