You could search for past examples of this very question for starters, but here's a technique that will give you the result that you seek:
ids = [ 3, 1, 2 ]
results = User.find(ids) sorted_results = results.sort_by {|u| ids.index(u.id) }
-Rob
Rob Biedenharn http://agileconsultingllc.com Rob@AgileConsultingLLC.com