dynamic select population based on result from another select_tag

Question

Hello,

I have a question with regards to this tricky situation. I have code for a single select box where I can select a year, and based on the year, I want to return all possible values pertaining to that year in another select tag....

<%= select "month_end", "year", MonthEnd.find(:all, :select => 'DISTINCT year', :order => 'year').collect{|x| [ x.year, x.id ]} %>

I've tried to use observe field but it doesnt work, I need some help please.

Thank you very much for any help, have a great x-mas/new years