rails中一个窗体多个模型——fields_for

借助field_for可以生成表单来处理两个或更多模型对象的数据

先看一个官方的例子，一个表单中有person和permission两个模型，其中每个person包含一个permission

<%= form_for(@person) do |person_form| %>

   First name: <%= person_form.text_field :first_name %>

   Last name: <%= person_form.text_field :last_name %>

<% fields_for :permission, @person.permission do |permission_fields| %>

     Admin : <%= permission_fields.check_box :admin %>

   <% end %>

 <% end %>  

当一个person包含多个permission时，view代码如下

<%= form_for(@person) do |person_form| %>

   First name: <%= person_form.text_field :first_name %>

   Last name: <%= person_form.text_field :last_name %>

<% for permission in @person.permissions %>

     <%= fields_for "permission[]", permission do |permission_fields| %>

       Admin : <%= permission_fields.check_box :admin %>

     <% end %>

   <% end %>

<% end %>  

1、其中"permission[]"保证了多个permission对象id不同，都包含在param[]中

2、此时，param[:person]={:first_name => v, :last_name => v, :permission1=>v,
:permission2 => v...}

3、<%=person_form.fields_for
"permission[]", permission do |permission_fields| %>时，

param[:person]={:first_name => v, :last_name => v, :persom=>{:permission1=>v,
:permission2 => v...}}

model代码

# models/.person.rb

def permission_attributes=(permission_attributes)

  permission_attributes.each do |attributes|

    permissions.build(attributes)

  end

end  

为了对应view里面的permission[]

controller里的create方法

# persons_controller.rb

def new

  @person= person.new

  3.times { @person.permissions.build }

end

def create

  @person= Person.new(params[:project)

  if @person.save

    flash[:notice] = "Successfully created project."

    redirect_to persons_path

  else

    render :action => ‘new‘

  end

end  

rails中一个窗体多个模型——fields_for