为什么这个呈现:部分行重复我的集合两次?

考虑到这些关系:

class Account < ActiveRecord::Base
  has_many :employments
  has_many :people, :through => :employments
  accepts_nested_attributes_for :employments
end

class Employment < ActiveRecord::Base
  belongs_to :account
  belongs_To :person
end

我想列出一个账户的就业记录:

<% form_for @account do |f| -%>
  <% f.fields_for :employments do |e| -%>
    <%= render :partial => 'employment', :collection => @account.employments, :locals => { :f => e } %>
  <% end -%>
<% end -%>  

我已经验证@account中的就业表包含两个记录,但我得到了部分的四个副本,因为它重复两次就业:

Employment Load (1.0ms)   SELECT * FROM [employments] WHERE ([employments].account_id = 1) 
Person Load (1.3ms)   SELECT * FROM [people] WHERE ([people].[id] = 2) 
Rendered accounts/_employment (17.9ms)
Person Load (1.5ms)   SELECT * FROM [people] WHERE ([people].[id] = 1) 
Rendered accounts/_employment (5.1ms)
Rendered accounts/_employment (2.2ms)
Rendered accounts/_employment (2.1ms)

有人能解释为什么会这样吗?

以下是一些附加信息:

这个 _employment.html.erb 部分:

<div class="employment">
  <span class="name"><%= link_to h(employment.person.name), person_path(employment.person) %></span>
  <span class="role"><%=h employment.role %></span>
  <span class="commands"><%= remove_child_link "Remove", f %></span>
</div>

remove_child_link 是唯一需要生成表单域的位置。它创造了 _delete 记录的字段并连接一个将值更改为“1”的删除链接。“role”属性也可以编辑。重要的是,我不希望所有字段都可编辑。

这个 accounts_controller 此视图的操作:

def edit
  @account = Account.find(params[:id])
end

def update
  @account = Account.find(params[:id])

  respond_to do |format|
    if @account.update_attributes(params[:account])
      flash[:notice] = "#{@account.business_name} was successfully updated."
      format.html { redirect_to @account }
    else
      format.html { render :action => "edit" }
    end
  end
end

本让我走对了方向。一些运行时检查显示记录存储在 object 变量(我已经知道,但在另一个上下文中)。所以我可以重写 fields_for 条款如下:

<% form_for @account do |f| -%>
  <% f.fields_for :employments do |e| -%>
    <div class="employment">
      <span class="name"><%= link_to h(e.object.person.name), person_path(e.object.person) %></span>
      <span class="role"><%=h e.object.role %></span>
      <span class="commands"><%= remove_child_link "Remove", e %></span>
    </div>
  <% end -%>
<% end -%>