让关联的model以下拉菜单(select)的形式显示

1. 先使用rails命令行generate scaffold来生成将要用到的各个组件。

a) Sex

rails generate scaffold Sex name:string

b) Person

rails generate scaffold Person name:string birthday:date salary:decimal sex:references

2. 生成数据库表：

rails db:migrate

3. 修改页面: 主要是在edit页面上让sex以下拉菜单的形式显示。

a) app/views/people/_form.html.erb

<%= form_for(@person) do |f| %>  <% if @person.errors.any? %>    <div id="error_explanation">      <h2><%= pluralize(@person.errors.count, "error") %> prohibited this person from being saved:</h2>      <ul>      <% @person.errors.full_messages.each do |msg| %>        <li><%= msg %></li>      <% end %>      </ul>    </div>  <% end %>  <div class="field">    <%= f.label :name %><br />    <%= f.text_field :name %>  </div>  <div class="field">    <%= f.label :birthday %><br />    <%= f.date_select :birthday %>  </div>  <div class="field">    <%= f.label :salary %><br />    <%= f.text_field :salary %>  </div>  <div class="field">    <%= f.label :sex %><br />    <%= f.select(:sex_id, Sex.all.map { |sex| [sex.name, sex.id] }, :prompt => true) %>  </div>  <div class="actions">    <%= f.submit %>  </div><% end %>

b) app/views/people/index.html.erb

<h1>Listing people</h1><table>  <tr>    <th>Name</th>    <th>Birthday</th>    <th>Salary</th>    <th>Sex</th>    <th></th>    <th></th>    <th></th>  </tr><% @people.each do |person| %>  <tr>    <td><%= person.name %></td>    <td><%= person.birthday %></td>    <td><%= person.salary %></td>    <td><%= person.sex.name %></td>    <td><%= link_to 'Show', person %></td>    <td><%= link_to 'Edit', edit_person_path(person) %></td>    <td><%= link_to 'Destroy', person, confirm: 'Are you sure?', method: :delete %></td>  </tr><% end %></table><br /><%= link_to 'New Person', new_person_path %>

c）app/views/people/show.html.erb

<p id="notice"><%= notice %></p><p>  <b>Name:</b>  <%= @person.name %></p><p>  <b>Birthday:</b>  <%= @person.birthday %></p><p>  <b>Salary:</b>  <%= @person.salary %></p><p>  <b>Sex:</b>  <%= @person.sex.name %></p><%= link_to 'Edit', edit_person_path(@person) %> |<%= link_to 'Back', people_path %>

4. 修改model : person.rb 如下：

class Person < ActiveRecord::Base  belongs_to :sex  validates :sex_id, :presence => true  validates :name, :uniqueness => trueend