Select tag Association With Javascript - Ruby On Rails

// Javascript

function update_states_div(country_id) {
  jQuery.ajax({
    url: "/update_states",
    type: "GET",
    data: {"country_id" : country_id},
    dataType: "html"
    success: function(data) {
      jQuery("#statesDiv").html(data);
    }
  });
}


// Controller

def new
  @User = User.new
  @countries = Country.all
  @states = State.al
end

def edit
  @User = User.find(params[:id])
  @countries = Country.all
  @states = State.all
end

def update_states
  @states = State.where(country_id => params[:country_id])
  render :partial => "states", :object => @states
end


// View

<%= select_tag "country_id", options_from_collection_for_select(@countries, "id", "name"), :prompt => "Select Your Country", :onchange => "update_states_div(this.value)" %>
<div id="statesDiv">
  <%= render :partial => 'states', :object => @states %>
</div>


// Partial: _state.html.erb

<%= select_tag "state_id", options_from_collection_for_select(states, "id", "name"), :prompt => "Select State" %>

// Also add a route for /update_states in your routes.rb

match "/update_states" => "users#update_states"