JA's K2 Search and Filter add-on is a nice - and powerful tool. But has an annoying problem (at least in version 1.0.7): When one edit a K2 item which have extra fields, on save an ugly error 1062 database error is popping up. The component is working correctly, the modified date is saved, but the user  doing the update gets seriously confused.

Recently a customer of mine asked for a page with a list of K2 items, sortable by the custom fields and item titles. And I accepted the challenge. a first search on the "k2 list sort by extra fields" term returned a whopping number of 1,120,000+ results... and most of them where how to hack the core component to obtain a list sorted by a given extra field - which was not what I wanted. But, reading these pages an ideea sparkled - and in less, than a hour I had in place a solution wich was clean, no core code was hacked, and the table of results is freely sortable.