单元测试与固定装置的多态关联答案

【问题标题】：Unit testing a polymorphic association with fixtures单元测试与固定装置的多态关联
【发布时间】：2015-01-02 15:48:44
【问题描述】：

我收到此错误消息：

ERROR["test_profile_display", UsersProfileTest, 2.569931] test_profile_display#UsersProfileTest (2.57s)
NoMethodError:         NoMethodError: undefined method `posts' for nil:NilClass
        app/controllers/users_controller.rb:14:in `show'
        test/integration/users_profile_test.rb:22:in `block in <class:UsersProfileTest>'
    app/controllers/users_controller.rb:14:in `show'
    test/integration/users_profile_test.rb:22:in `block in <class:UsersProfileTest>'

似乎@posts = @user.character.posts.paginate(page: params[:page]) 行中的UsersController 中的character 为零。用户和角色之间存在多态关系。我以为我在fixtures中使用了正确的语法来告诉rails用户Bazley有一个fixture：在characters.yml中：

character_bazley:
  sociable: bazley (user)

我如何让 rails 相信用户夹具确实有属于它的角色？

测试/集成/users_profile_test.rb：

require 'test_helper'

class UsersProfileTest < ActionDispatch::IntegrationTest
  include ApplicationHelper

  def setup
    @user = users(:bazley)
  end

  test "profile display" do
    log_in_as(@user)
    get user_path(@user)
    assert_template 'users/show'
    assert_select 'title', full_title(@user.name)
    assert_select 'h1', text: @user.name
    assert_select 'h1>img.gravatar'
    assert_match @user.character.posts.count.to_s, response.body
    assert_select 'div.pagination'
    @user.character.posts.paginate(page: 1).each do |post|
      assert_match post.content, response.body
    end
  end
end # UsersProfileTest

user.rb:

class User < ActiveRecord::Base

  attr_accessor :remember_token, :activation_token, :reset_token
  has_one  :character, as: :sociable, dependent: :destroy
  .
  .
end

字符.rb：

class Character < ActiveRecord::Base

  belongs_to :sociable, polymorphic: true
  has_many   :posts, dependent: :destroy
  validates  :sociable_id, presence: true
end # Character

users.yml:

bazley:
  name: Bazley
  email: bazley@oxdorf.com
  callsign: bazley
  password_digest: <%= User.digest('password') %>
  admin: true
  activated: true
  activated_at: <%= Time.zone.now %>

characters.yml：

character_bazley:
  sociable: bazley (user)

在用户控制器中：

def show
  @user = User.find_by_callsign(params[:callsign])
  @posts = @user.character.posts.paginate(page: params[:page]) # the line causing the error
  @page_name = "user_page"
  redirect_to root_url and return unless @user.activated
end

【问题讨论】：

标签： ruby-on-rails fixtures

【解决方案1】：

将characters.yml 更改为

character_bazley:
  sociable: bazley (User)

而不是

character_bazley:
  sociable: bazley (user)

注意它是User 而不是user。此处使用的关键字User 将表明sociable_type 属于User 类。

参考：

http://ruby-journal.com/rails/define-fixtures-with-polymorphic-association/ http://api.rubyonrails.org/v3.2.8/classes/ActiveRecord/Fixtures.html#label-Polymorphic+belongs_to

【讨论】：

天哪，一个大写字母……我是个笨蛋。谢谢。