如何从父控制器保存子记录？

Question

我已经保存了一堆'kid'对象,我想创建一个父对象,通过'亲戚'模型链接到孩子.

这个对象通过亲戚给了我一对多.

需要说明的是:用户访问"父母"页面,单击创建父母,并显示一个表单,该表单允许他们为父母命名并将最多四个孩子添加到此父母(通过创建"亲戚"),这些关系中的每一个'也被命名 - 这是一个重要的部分.因此,我可以将关系称为"步子"或"儿子".

这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", force: :cascade do |t|
    t.string   "name"
    t.datetime "created_at", null: false
    t.datetime "updated_at", 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
    t.datetime "updated_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.这不应该自动发生吗？

我已经尝试循环遍历:relatives_attributes,但这似乎不适用于'build'.

我怎么想让"亲戚"记录保存？

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"=>"", "_destroy"=>"0"},
     "2"=>{"kid_id"=>"", "relationship"=>"", "_destroy"=>"0"},
     "3"=>{"kid_id"=>"", "relationship"=>"", "_destroy"=>"0"}}}

编辑:我已更新此内容以显示我的最新编辑 - 请注意'parent_params [:relatives_attributes] .each do | k,r |' 在控制器中.这现在保存了孩子记录,但唯一的问题是,它还保存了空白的字段!所以我有'亲戚'记录,其中包含小孩记录的空值.如何停止保存空字段(或创建空的相对记录)？

Answer 1

答案是构建亲戚的每个子记录，如下所示：

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

在调用@parent.save之前。

但是，我在删除空白记录时仍然遇到问题。因此，如果有人对这个问题有答案，请在这里发表评论 - 或者如果有更好或更传统的方法来做到这一点，请联系我。在这里跟进问题：为什么我的模型中的reject_if不拒绝空白记录？