How to reverse comments order in Drupal 7? Simple task impossible?

Well, I'm surprised, but it doesn't look like you can do that without hacking core. However, based on the comments in that function and some quick testing, loading comments in reverse order is surprisingly tricky when you're dealing with comments and replies to comments. Just switching ASC to DESC yields some pretty non-intuitive results.

Thank you for pointing out the function. There is a comment that clarifies the sorting issue. And as much as I understand at this fairly late hour, DESC is where it gets somewhat tricky (Thread mode, of course. There's nothing special about Flat mode as it executes a simple 'SORT BY comment id' query).

My project runs comments as a guestbook on one page only. So the structure [ Comment - One Answer ] is all I need and here is what I've done to make this work for me:

  else {
    // See comment above. Analysis reveals that this doesn't cost too
    // much. It scales much much better than having the whole comment
    // structure.
    $query->orderBy('c.thread', 'DESC');
  }

However, when it comes to sorting multiple child comments this is not gonna work (again, the function comment for more info). One more thing: the submit function requires attention as it redirects to the last page.

I'm not a drupal expert either, but I don't feel bad to change the core module a little bit. The thing I was really surprised about is that nothing has changed in developer versions yet.

Since i still couldn't find any solution for that, i developed a little module to sort comments on nodes. If you want you can download & try it at http://ganovelli.it/project/sort_comments. Let me know if works for you.

I submitted a Feature Request..
http://drupal.org/node/1193520

I'm using http://drupal.org/project/sort_comments and it's working good so far..

Anyway, that's really bad to remove a feature present in 6.x core...

those who don't want to use module ...don't forget to clear cache.

* Implements hook_query_TAG_alter().
 *
 * Alter comments query to order by DESC as well as the default ASC.
 */
function modulename_query_comment_filter_alter(QueryAlterableInterface $query) {
  $orderby = &$query->getOrderBy();
  $expressions = &$query->getExpressions();
  // Sorting for threaded comments.
  if (isset($orderby['torder'])) {
    // Get rid of the expressions that prepare the threads for ASC ordering.
    unset($expressions['torder']);
    unset($orderby['torder']);
    // Simply order by the thread field.
    $orderby['c.thread'] = 'DESC';
  }
  // Sorting for flat comments.
  else {
    $direction = 'DESC';
    if (isset($orderby['c.cid'])) {
      unset($orderby['c.cid']);
    }
    $orderby['c.created'] = $direction;
    $orderby['c.cid'] = $direction;
  }
}

Im using the code above:

/* Implements hook_query_TAG_alter(). 
* * Alter comments query to order by DESC as well as the default ASC. */
function currents_query_comment_filter_alter(QueryAlterableInterface $query) {
    $orderby = &$query->getOrderBy();  
    $expressions = &$query->getExpressions();  
    // Sorting for threaded comments. 
    if (isset($orderby['torder'])) {   
       // Get rid of the expressions that prepare the threads for ASC ordering.
        // Simply order by the thread field.
            
            unset($expressions['torder']);
            unset($orderby['torder']);
           $orderby['c.thread'] = 'DESC';   
           
         
    }else{  // Sorting for flat comments.   
        $direction = 'DESC';
        if (isset($orderby['c.cid'])) {
            unset($orderby['c.cid']);    
        }
        $orderby['c.created'] = $direction;
        $orderby['c.cid'] = $direction; 
    }

}

which gives me the descending order. However is there a way to modify this so it only effect threads at the top level (i.e. XX/) while preserving the ascending order for replies to threads. (i.e. xx.xx/ or xx.xx.xx/, etc)?

Thanks fiftyz

This worked for me.

For Drupal 8 you can use the next module: Comments order.

It solves this problem.