Well, the acf/pre_save_post hook does not run in the admin.
There really isn’t any way to tell if the post is a new post or being updated during acf/save_post. The only way that you’ll be able to do this is to… to be honest, I’m not sure.
You can either set a flag that says tells you or you can possible check the file that you unzipped to see if it exists.
I don’t know how to do the second one, possibly get the attachment and see if it’s a .zip or something else. I’m not exactly sure about the unzipping a file since you can’t know what it contains, so it’s not very secure.
You could set a hidden meta value, you hide meta values by starting the name with an underscore.
To add to the conditions
if (!is_numeric($post_id) || get_post_type($post_id) != 'files') {
return;
}
$done_this = get_post_meta($post_id, '_done_this', true);
if ($done_this) {
// we already did the unzipping, don't do it again
return;
}
// set the value so we won't do it again
update_post_meta($post_id, '_done_this', true);
// now do the file unzipping
