How do i access an id from select box?

I have a form which has a select box with name of cities from the database. When i select a city and click continue, i want it to grab the city_id selected and redirect me to another page (:controller=> 'people', action => 'index') where i am going to make use of that city_id. How do i do that?Iam using RAILS 3.This is what i have..

View

 <%= form_for :c开发者_StackOverflow社区ities, :url=>{:action =>"next"} do |f| %>
<%= collection_select(nil, :city_id, City.all, :id, :name ,:prompt=>"Select your city") %>
<%=f.submit "continue" %>
 <%end%>

Controller

class HomeController < ApplicationController
  def next
    @city = City.find(params[:city_id]) 
    redirect_to :controller => "people", :action => "index"
  end
  def new
    @city = City.new
  end
end

People Controller

class PeopleController < ApplicationController
  def index
    @city = City.find(params[:city_id])
  end
end

You can do this by setting a session variable in your next action:

class HomeController < ApplicationController
  def next
    @city = City.find(params[:city_id])
    session[:city_id] = @city.id
    redirect_to :controller => "people", :action => "index"
  end
  def new
    @city = City.new
  end
end

class PeopleController < ApplicationController
  def index
    unless session[:city_id].nil? || session[:city_id].blank?
      @city = City.find(session[:city_id])
      # do your stuff here
    end
  end
end

You can also do this with a flash variable, but session is likely the proper place.