Change post status based on meta value

I have this cron set up to trash posts x days after it is posted. This works. Edit: Added my answer to my question.

add_action( 'wp', 'do_trash_ads' );
function do_trash_ads()
{
    if ( ! wp_next_scheduled( 'delete_classifieds' ) )
        wp_schedule_event( time(), 'daily', 'delete_classifieds' );
}

add_action( 'delete_classifieds', 'expire_posts' );
function expire_posts()
{
    global $wpdb;
    $daystogo = "14";

    $post_ids = $wpdb->get_results( "
        SELECT ID 
        FROM {$wpdb->posts}
        WHERE post_type="classifieds" 
        AND post_status="publish" 
        AND DATEDIFF(NOW(), post_date) > '{$daystogo}'
    " );
    foreach( $post_ids as $id )
    {
        $postid =  $id->ID;

        $my_post = array();
        $my_post['ID'] = $postid;
        $my_post['post_status'] = 'trash';
        wp_update_post( $my_post );
    }
}  

What I would like to do: Include posts in the above function that are based on a meta field value (21 days is the default, but a user can select an earlier date).

I set up a 2nd cron to do this.

add_action( 'wp', 'do_trash_ads_user' );
function do_trash_ads_user()
{
    if ( ! wp_next_scheduled( 'delete_ads_user' ) )
        wp_schedule_event( time(), 'daily', 'delete_ads_user' );
}

add_action( 'delete_ads_user', 'expire_posts_user' );
function expire_posts_user()
{
   global $wpdb;

   $post_ids = $wpdb->get_results( "
      SELECT ID 
      FROM {$wpdb->posts}
      WHERE post_type="classifieds" 
      AND post_status="publish"
   " );

   foreach( $post_ids as $id )
   {
       $postid =  $id->ID;
       $expiration_value = get_post_meta( $postid, 'ecpt_ad-expire-date', true );

       if( $expiration_value )
       {
           $todays_date = date( "Y-m-d" );
           $today = strtotime( $todays_date );
           $expiration_date = strtotime( $expiration_value );
           if ( $expiration_date > $today )
           { 

           }
           else
           { 
               $my_post = array();
               $my_post['ID'] = $postid;
               $my_post['post_status'] = 'trash';

               wp_update_post( $my_post );
           }
        }
    }
}

I don’t know if this is the best method but it is working.

Your code looks okay, and considering you are not submitting user entered data, the prepare() method isn’t required, but as a matter of best-practice it’s good to learn how it works and use it consistently.

With that said, using the prepare() method, your code would look like this:

$sql = $wpdb->prepare( "
  SELECT ID
  FROM %s
  WHERE post_type="classifieds" 
  AND post_status="publish"
  ", $wpdb->posts );

 $post_ids = $wpdb->get_results( $sql, ARRAY_A );

Also, You could shorten your if statement from:

if ( $expiration_date > $today )
           { 

           }
           else
           { 
               $my_post = array();
               $my_post['ID'] = $postid;
               $my_post['post_status'] = 'trash';

               wp_update_post( $my_post );
           }

to:

if ( $expiration_date < $today )
           { 
               $my_post = array();
               $my_post['ID'] = $postid;
               $my_post['post_status'] = 'trash';
               wp_update_post( $my_post );
           }