Dear friends, with the yours aid already I obtained to use observe_field, but still I am with some problems and necessary again. They are three questions to long of the source code below. Since already I am grateful for the tips. ==== _form.rhtml <!--[form:city]--> <p><label for="city_state_country_id">Pa?s</label><br/> <select id="city_state_country_id" name="city.state[country_id]"> *** QUESTION 1: How I can know if I am in the action new or edit without needing to create the @is_new variable? <% if @is_new %> <option selected value="0">Selecione um Pa?s</option> <% @form_country_id = 0 %> <% else%> <% @form_country_id = @city.state["country_id"] %> <% end%> <%= options_from_collection_for_select @countries, "id", "nome", @form_country_id %> </select></p> <%= observe_field(:city_state_country_id, :update => :select_state, :url => {:action => :ajax_states_from_country} ) %> *** QUESTION 2: How to force the exhibition of select_state when the page is loaded and it did not have change of value of country_id? This operation is necessary to show the state field in the edition action of the data. <p><label for="city_state_id">Estado</label><br/></p> <div id="select_state"></div> . . . ==== city_controller.rb *** QUESTION 3: How I can receive the value from @form_country_id for parameter? Not to need to use request.raw_post... def ajax_states_from_country @states = State.find(:all, :order => "nome", :conditions => ["country_id = ?", request.raw_post]) render(:layout => false) end ==== ajax_states_from_country.rhtml ... and not to use @form_country_id variable from _form.rhtml. <select id="city_state_id" name="city[state_id]"> <%= options_from_collection_for_select @states, "id", "nome", @form_country_id %> </select> Regards, Eleudson Queiroz jinfo@mandic.com.br -- Posted via http://www.ruby-forum.com/.