rubyonrails 下实现菜单级联

很多时候我们需要实现菜单的级联。那么在ROR中怎么实现： 首先 分别创建3个资源： ruby script/generate scaffold country name:string ruby script/generate scaffold city country_id:integer name:string ruby script/generate scaffold person country_id:integer city_id:integer name:string 他会分别创建国家、城市、人员3个资源 其次，创建数据库。 rake db:create创建数据库 rake db:migrate 迁移数据 第三，model建立关系 class City < ActiveRecord::Base belongs_to :country has_many :people end class Country < ActiveRecord::Base has_many :cities has_many :people end class Person < ActiveRecord::Base belongs_to :country belongs_to :city end 第四，修改app/views/layouts/people.rhtml，包含prototype： <%= javascript_include_tag 'prototype' %> 第五，修改people/new.html.erb <p> <b>Country</b><br /> <%= f.select (:country_id, Country.find(:all).collect {|c| [ c.name, c.id ] }, { :include_blank => true }, :onchange => remote_function(:update => "cities", :method => "get", :with => "'country_id=' + value + '&partial=select'", :url => { :controller => :cities, :action => :index})) %> </p><p> <b>City</b><br /> <div id="cities"> <%= f.select (:city_id, []) %> </div> </p> 第六，修改city_controller 的index方法: def index if params[:country_id] @cities = City.find(:all, :conditions => ["country_id = ?", params[:country_id]]) else @cities = City.find(:all) end respond_to do |format| format.html { render :partial => params[:partial]} format.xml { render :xml => @districts.to_xml } end end 第七：创建_select.html.erb模板 <%= select(:person, :city_id, @cities.collect {|c| [c.name, c.id]}) %>