rails 3 的一对一的关联
主要将 ActiveRecord? 一对一关联的实例：
? Classroom? has one? Teacher
classroom 的属性： name,capacity,teacher
teacher 的属性：name,sex,age
利用Scaffold 生成器：
$ rails g scaffold teacher name:string sex:string age:integer$ rails g scaffold classroom name:string capacity:integer teacher:references
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Scaffold 已经为我们生成了基本的程序框架了。
然后修改app/views/classroom/_form.html.erb 的内容，添加选择老师的下拉框，并且为每个输入框添加默认值。
<%= form_for(@classroom) do |f| %> <% if @classroom.errors.any? %> <div id="error_explanation"> <h2><%= pluralize(@classroom.errors.count, "error") %> prohibited this classroom from being saved:</h2> <ul> <% @classroom.errors.full_messages.each do |msg| %> <li><%= msg %></li> <% end %> </ul> </div> <% end %> <div class="field"> <%= f.label :name %><br /> <%= f.text_field :name ,{:value => "梨花教师"} %> </div> <div class="field"> <%= f.label :capacity %><br /> <%= f.number_field(:capacity,{:value => 20}) %> </div> <div class="field"> <%= f.label :teacher %><br /> <%= f.select(:teacher_id,Teacher.all.collect{|p| [p.name,p.id]},{:include_blank =>"选择老师...",:selected=>2}) %> </div> <div class="actions"> <%= f.submit %> </div><% end %>?
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修改app/views/classroom/index.html.erb 的内容：
<td><%= classroom.teacher.name %></td>
即可。
访问地址 http://localhost:3000/classrooms 即可添加内容和结果了