Rails 嵌套资源和设计

Question

假设我有一个名为“User”的设计模型，它拥有 :notes 和 :notebooks 以及每个 :notebook has_many :notes。

所以一个笔记会有两个外键:user_id和:notebook_id，那么如何构建/查找笔记呢？

current_user.notebooks.find(param).notes.new(params[:item]) 将仅为笔记本创建foreign_key，还是为数据库中便笺记录中的用户创建foreign_key？

如果是第二种情况（外键只用于笔记本），我应该怎么写？

将 MongoDB 与 MongoID 和引用关系一起使用

Answer 1

Mongoid 将为您管理文档引用和查询，只需确保为您需要的每个方向指定关联/关系（例如，用户 has_many :notes 和 Note belongs_to :user）。与 ActiveRecord 一样，它似乎对关系“聪明”。请不要手动操作引用，而是让您的 ODM (Mongoid) 为您工作。当您运行测试（或使用 rails 控制台）时，您可以使用 tail -f log/test.log（或 log/development.log）查看 Mongoid 正在为您完成哪些 MongoDB 操作，您可以看到实际对象文件更新时的参考。您可以看到关系如何利用特定的对象引用，如果您注意这一点，链接优化应该会变得更加清晰。

以下模型和测试对我有用。可根据要求提供有关设置的详细信息。希望这会有所帮助。

型号

class User
  include Mongoid::Document
  field :name

  has_many :notebooks
  has_many :notes
end

class Note
  include Mongoid::Document
  field :text

  belongs_to :user
  belongs_to :notebook
end

class Notebook
  include Mongoid::Document

  belongs_to :user
  has_many :notes
end

测试

require 'test_helper'

class UserTest < ActiveSupport::TestCase

  def setup
    User.delete_all
    Note.delete_all
    Notebook.delete_all
  end

  test "user" do
    user = User.create!(name: 'Charles Dickens')
    note = Note.create!(text: 'It was the best of times')
    notebook = Notebook.create!(title: 'Revolutionary France')
    user.notes << note
    assert_equal(1, user.notes.count)
    user.notebooks << notebook
    assert_equal(1, user.notebooks.count)
    notebook.notes << note
    assert_equal(1, notebook.notes.count)
    puts "user notes: " + user.notes.inspect
    puts "user notebooks: " + user.notebooks.inspect
    puts "user notebooks notes: " + user.notebooks.collect{|notebook|notebook.notes}.inspect
    puts "note user: " + note.user.inspect
    puts "note notebook: " + note.notebook.inspect
    puts "notebook user: " + notebook.user.inspect
  end

end

结果

Run options: --name=test_user

# Running tests:

user notes: [#<Note _id: 4fa430937f11ba65ce000002, _type: nil, text: "It was the best of times", user_id: BSON::ObjectId('4fa430937f11ba65ce000001'), notebook_id: BSON::ObjectId('4fa430937f11ba65ce000003')>]
user notebooks: [#<Notebook _id: 4fa430937f11ba65ce000003, _type: nil, user_id: BSON::ObjectId('4fa430937f11ba65ce000001'), title: "Revolutionary France">]
user notebooks notes: [[#<Note _id: 4fa430937f11ba65ce000002, _type: nil, text: "It was the best of times", user_id: BSON::ObjectId('4fa430937f11ba65ce000001'), notebook_id: BSON::ObjectId('4fa430937f11ba65ce000003')>]]
note user: #<User _id: 4fa430937f11ba65ce000001, _type: nil, name: "Charles Dickens">
note notebook: #<Notebook _id: 4fa430937f11ba65ce000003, _type: nil, user_id: BSON::ObjectId('4fa430937f11ba65ce000001'), title: "Revolutionary France">
notebook user: #<User _id: 4fa430937f11ba65ce000001, _type: nil, name: "Charles Dickens">
.

Finished tests in 0.018622s, 53.6999 tests/s, 161.0998 assertions/s.

1 tests, 3 assertions, 0 failures, 0 errors, 0 skips

Answer 2

我会用

class User
  has_many :notebooks
  has_many :notes, :through => :notebooks
end

http://guides.rubyonrails.org/association_basics.html#the-has_many-through-association

更新

您总是可以像这样手动设置 user_id（我假设 param 是您笔记本的 ID？）：

Notebook.find(param).notes.new(params[:item].merge(:user_id => current_user.id))