这个对象给了我一对多,通过亲戚.

要明确：用户访问“父母”页面,点击创建父母,并提供一个表格,让他们命名父母,并加起来这个父母的四个孩子(通过创建“亲戚”),这些“关系” “也被命名 – 这是重要的一部分.所以,我可以命名关系“步子”或“儿子”.

以下是我到目前为止的代码：

class Kid < ActiveRecord::Base
  has_many :relatives
  has_many :parents,through: :relatives
end


class Parent < ActiveRecord::Base
  has_many :relatives
  has_many :kids,through: :relatives

  accepts_nested_attributes_for :relatives,:reject_if => lambda { |a| a[:content].blank? },:allow_destroy => true
end


class Relative < ActiveRecord::Base
  belongs_to :parent
  belongs_to :kid
end



class ParentsController < ApplicationController
  before_action :set_parent,only: [:show,:edit,:update,:destroy]
  before_action :lookup_kids,only: [:new,:edit]

  # GET /parents
  # GET /parents.json
  def index
    @parents = Parent.all
  end

  # GET /parents/1
  # GET /parents/1.json
  def show
  end

  # GET /parents/new
  def new    
    @parent = Parent.new
    4.times { @parent.relatives.build }
  end

  # GET /parents/1/edit
  def edit
  end

  # POST /parents
  # POST /parents.json
  def create
    @parent = Parent.new(parent_params)        

    parent_params[:relatives_attributes].each do |k,r|
      @parent.relatives.build(r.except(:_destroy))
    end

    respond_to do |format|
      if @parent.save
        format.html { redirect_to @parent,notice: 'Parent was successfully created.' }
        format.json { render :show,status: :created,location: @parent }
      else
        format.html { render :new }
        format.json { render json: @parent.errors,status: :unprocessable_entity }
      end
    end
  end

  # cut for brevity.



  private

    # Use callbacks to share common setup or constraints between actions.
    def set_parent
      @parent = Parent.find(params[:id])
    end


    def parent_params
      params.require(:parent).permit(:name,relatives_attributes: [:parent_id,:kid_id,:relationship,:_destroy])
    end
    def lookup_kids
      @kids = Kid.all #for this nursery.
    end
end





<%= form_for(@parent) do |f| %>
  <% if @parent.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@parent.errors.count,"error") %> prohibited this parent from being saved:</h2>
      <ul>

      <% @parent.errors.full_messages.each do |message| %>
        <li><%= message %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= f.label :name %><br>
    <%= f.text_field :name %>
  </div>

  <h4>Kids:</h4>
  <%= f.fields_for :relatives do |r| %>
    <%= r.label :kid %>
    <%= r.collection_select :kid_id,@kids,:id,:name,include_blank: true%>
    <%= r.label :relationship %>
    <%= r.text_field :relationship %>    
    <%= r.check_Box :_destroy %>
    <%= r.label :_destroy,"Remove" %>
    <br/>
  <% end %>

  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>



ActiveRecord::Schema.define(version: 20151030113634) do
  create_table "kids",force: :cascade do |t|
    t.string   "name"
    t.datetime "created_at",null: false
    t.datetime "updated_at",null: false
  end
  create_table "parents",null: false
  end
  create_table "relatives",force: :cascade do |t|
    t.string   "relationship"
    t.integer  "parent_id"
    t.integer  "kid_id"
    t.datetime "created_at",null: false
  end
  add_index "relatives",["kid_id"],name: "index_relatives_on_kid_id"
  add_index "relatives",["parent_id"],name: "index_relatives_on_parent_id"
end

当我在父母控制器中“创建”时,我可以看到正确的参数正在通过,但关系记录没有被保存.这不会自动发生吗？

我尝试循环遍历：relatives_attributes,但似乎不适用于“build”.

我怎样才能让“亲戚”记录得到保存？

编辑：添加参数发布：

parent"=>{
  "name"=>"Dad","relatives_attributes"=>{
     "0"=>{"kid_id"=>"2","relationship"=>"Son","_destroy"=>"0"},"1"=>{"kid_id"=>"","relationship"=>"","2"=>{"kid_id"=>"","3"=>{"kid_id"=>"","_destroy"=>"0"}}}

编辑：我已经更新了,以显示我的最新编辑 – 注意’parent_params [：relatives_attributes] .each do | k,r |’在控制器中.这样现在可以保存孩子的记录,但唯一的问题是它也保存了空白的字段！所以我的“亲戚”记录为空值为孩子记录.我如何阻止它保存空字段(或创建空的相对记录)？