Dropdown list

i am new to ruby and i have installed ferret for search using text box
for search by the string in
the text box
insted of that i am trying to implement a drop down list,with the
selected item in the drop down it should search. problem hear is that
the search is not going by the item please help me

The code is:

insted of this i tryied
<%= select_tag ‘category’,options_for_select([[‘ALL
[‘Commercial Land’],
[‘Industrial Building’],
[‘Industrial Shed’],
[‘Farm House’]], to_s), :onchange =>
“content.category(this,notnull ) ;” %>

please help me…
Thank you.