在自定义类中使用has_many / belongs_to关联手动分配父ID

Question

我使用自定义类从Feedjirra制作AR实例。我无法让子实例与其父对象相关联。

Show has_many :episodes - Episode belongs_to :show - show_id始终为nil。

RSpec记录@show.id和@episode.show_id彼此相同。但是，当我在开发中运行导入后运行episode = Episode.first时，该集的show_id设置为nil。

@show = Show.new

@show.name = @feed.title
@show.description = @feed.description
...

if @show.save
  puts "@show.id: #{@show.id}"
end

@episodes = []

@feed.entries.each do |item|
    @episodes.push(item)
end

@episodes.each do |item|
    @episode = @show.episodes.new

    @episode.name = item.title
    @episode.description = item.summary
    ...

    if @episode.save
      puts "@episode.show_id: #{@episode.show_id}"
    end
end

我尝试使用@episode = @show.episodes.create，@episode = Episode.new和@episode.show_id = @show.id。它们都记录了匹配的ID，但实例上的show_id仍为nil。每隔一列都填写正确。

我认为这个问题可能与使用add_foreign_key：

有关

class AddShowToEpisodes < ActiveRecord::Migration
  def change
    add_reference :episodes, :show, index: true
    add_foreign_key :episodes, :shows, column: :show_id
  end
end

所以我删除了它并使用了标准foreign_key: true，但它没有效果。

class RemoveShowFromEpisodes < ActiveRecord::Migration
  def change
    remove_column :episodes, :show_id
  end
end

class AddShowBackToEpisodes < ActiveRecord::Migration
  def change
    add_reference :episodes, :show, index: true, foreign_key: true
  end
end

以下是完整代码以防万一。

importers_controller.rb：

class Admin::ImportersController < Admin::ApplicationController
  before_action :set_importer, only: [:show, :edit, :update, :destroy]

  def index
    @importers = policy_scope(Importer)
  end

  def show
  end

  def new
    @importer = Importer.new
    authorize @importer
  end

  def create
    @importer = Importer.new(importer_params)
    authorize @importer

    if @importer.save
      require "subscription_importer"
      SubscriptionImporter.new(@importer)

      flash[:notice] = "Importer added."
      redirect_to admin_importers_path
    else
      flash[:error] = "Importer not added."
      render "new"
    end
  end

  def edit
  end

  def update
  end

  def destroy
  end

  private

  def set_importer
    @importer = Importer.find(params[:id])
    authorize @importer
  end

  def importer_params
    params.require(:importer).permit(:name, :url, :source)
  end
end

subscription_importer.rb：

class SubscriptionImporter
  def initialize(importer)
    @importer = importer
    @feed = Feedjira::Feed.fetch_and_parse @importer.url

    if @importer.source === "iTunes"
      itunes_parser(@importer)
    end
  end

  def itunes_parser(importer)
    @importer = importer

    # Parser
    @feed = Feedjira::Feed.fetch_and_parse @importer.url

    # Show
    @show = Show.new

    @show.name = @feed.title
    @show.description = @feed.description
    @show.logo = @feed.itunes_image
    @show.explicit = explicit_check(@feed.itunes_explicit)
    @show.genre = @feed.itunes_categories
    @show.tags = @feed.itunes_keywords
    @show.url = @feed.url
    @show.language = @feed.language

    if @show.save
      puts "Show import succeeded"
      puts "@show.id: #{@show.id}"
    else
      puts "Show import failed"
    end

    # Episodes
    @episodes = []

    @feed.entries.each do |item|
        @episodes.push(item)
    end

    @episodes.each do |item|
        @episode = @show.episodes.new

        @episode.name = item.title
        @episode.description = item.summary
        @episode.release = item.published
        @episode.image = item.itunes_image
        @episode.explicit = explicit_check(item.itunes_explicit)
        @episode.tags = item.itunes_keywords
        @episode.url = item.enclosure_url
        @episode.duration = item.itunes_duration

        if @episode.save
          puts "Episode import succeeded"
          puts "@episode.show_id: #{@episode.show_id}"
        else
          puts "Episode import failed"
        end
    end
  end

  def explicit_check(string)
    if string == "yes" || "Yes"
      true
    else
      false
    end
  end
end

create_importer_spec.rb：

require "rails_helper"

RSpec.feature "Admins can create importers" do
  let(:user) { FactoryGirl.create(:user, :admin) }

  context "admins" do
    before do
      login_as(user)
      visit "/"
      click_link "Admin"
      click_link "Importers"
      click_link "New Importer"
    end

    scenario "with valid credentials" do
      fill_in "Name", with: "The Stack Exchange Podcast"
      fill_in "Url", with: "https://blog.stackoverflow.com/feed/podcast/" # Needs stubbing
      select "iTunes", from: "Source"
      click_button "Create Importer"

      expect(page).to have_content "Importer added"
      expect(page).to have_content "The Stack Exchange Podcast"
    end

    scenario "with invalid credentials" do
      fill_in "Name", with: ""
      fill_in "Url", with: ""
      click_button "Create Importer"

      expect(page).to have_content "Importer not added"
    end
  end
end

Answer 1

我认为episodes类中的SubscriptionImporter功能导致问题......

@episodes = []

@feed.entries.each do |item|
  @episodes.push(item) #-> each "@episodes" is a FeedJirra object
end

@episodes.each do |episode|
   #-> you're now creating an episode in the same call as show, which will either mean that show is not persisted or perhaps some other error 
end

我个人会将SubscriptionImporter功能限制为仅返回数据。您应该通过相应的模型解析该数据：

#app/controllers/admin/importers_controller.rb
class Admin::ImportersController < Admin::ApplicationController
   def create
      @import = Importer.new import_params 
      if @import.save
         @import.parse_show if @import.itunes?
      end
   end

   private

   def import_params
      params.require(:importer).permit(:name, :url, :source)
   end
end

#app/models/importer.rb
class Importer < ActiveRecord::Base
   def feed
      return false unless itunes?
      origin = Feedjirra::Feed.fetch_and_parse(self.url)
      return {
         name:        origin.title,
         description: origin.description,
         logo:        origin.itunes_image,
         explicit:    explicit_check(origin.itunes_explicit),
         genre:       origin.itunes_categories,
         tags:        origin.itunes_keywords,
         url:         origin.url,
         language:    origin.language,
         entries:     origin.entries
      }
   end

   def parse_show
      Show.create(feed)
   end

   def itunes?
      self.source == "iTunes" #-> true/false 
   end

   private

   def explicit_check
      string == "yes" || "Yes" #-> true/false
   end
end

#app/models/show.rb
class Show < ActiveRecord::Base
   has_many :episodes

   attr_accessor :entries
   after_create :create_episodes #-> might not persist entries

   def create_episodes
      if self.entries.any?
          self.entries.each do |item|
             self.episodes.create({
                name: item.title
                description: item.summary,
                release:     item.published,
                image:       item.itunes_image,
                explicit:    explicit_check?(item.itunes_explicit),
                tags:        item.itunes_keywords,
                url:         item.enclosure_url,
                duration:    item.itunes_duration
             })
          end
      end
   end

   private

   def explicit_check?
      string == "yes" || "Yes"
   end
end

以上内容允许您创建@importer，从中提取feed，然后填充Show＆amp; Episode模型包含返回的数据。

虽然应解决您的问题，但您需要考虑OOP - 将每个元素作为对象。

<强>更新

如果你想更加客观化，那么就有一个简单的模式：

1. Importer就是你需要保存的 - 其他一切都应该围绕这个
发生
2. Show + Episode 可以为我所知道的所有类/表

考虑到这一点，您可以执行以下操作：

#app/controllers/admin/importers_controller.rb
class Admin::ImportersController < Admin::ApplicationController
   def create
      @import = Importer.new import_params 
      @import.save
   end

   private

   def import_params
      params.require(:importer).permit(:name, :url, :source)
   end
end

#app/services/feed.rb
class Feed
    attr_reader :params, :show, :episode, :origin
    def initialize(params)
      @params = params
    end

    def origin
       @origin = Feedjirra::Feed.fetch_and_parse params[:source]
    end

    def show
       @show = ShowHelper.new @origin
    end

    def episodes
      @show.episodes
    end
end

#app/services/show_helper.rb
class ShowHelper 
    attr_reader :origin
    def initialize(origin)
      @origin = origin
    end

    def name
      @origin.title
    end

    def description
      @origin.summary || @origin.description
    end

    def logo
      @origin.itunes_image
    end

    def explicit
      %r{^yes$} =~ @origin.itunes_explicit
    end

    def genre
      @origin.itunes_categories
    end

    def tags
      @origin.itunes_keywords
    end

    def url
      @origin.url
    end

    def language
      @origin.language
    end

    def episodes
      @origin.entries
    end
end

#app/models/importer.rb
class Importer < ActiveRecord::Base
   after_create :parse_show, if: "itunes?"
   validates :source, :url, :name, presence: true

   def itunes?
      source == "iTunes" 
   end

   def feed
      @feed = Feed.new(self)
   end

   private

   def parse_show
      @show = Show.new(feed.show) if feed && feed.show
      if @show.save && @show.entries.any?
         @show.entries.each do |entry|
            @show.episodes.create ShowHelper.new(entry)
         end
      end
   end
end