FactoryGirl和多态关联

该设计

我有一个通过多态关联属于某个配置文件的用户模型。我选择此设计的原因可以在这里找到。总而言之，该应用程序有许多用户具有完全不同的配置文件。

class User < ActiveRecord::Base
  belongs_to :profile, :dependent => :destroy, :polymorphic => true
end

class Artist < ActiveRecord::Base
  has_one :user, :as => :profile
end

class Musician < ActiveRecord::Base
  has_one :user, :as => :profile
end

选择此设计后，我很难进行良好的测试。使用FactoryGirl和RSpec，我不确定如何以最有效的方式声明关联。

第一次尝试

factory.rb

Factory.define :user do |f|
  # ... attributes on the user
  # this creates a dependency on the artist factory
  f.association :profile, :factory => :artist 
end

Factory.define :artist do |a|
  # ... attributes for the artist profile
end

user_spec.rb

it "should destroy a users profile when the user is destroyed" do
  # using the class Artist seems wrong to me, what if I change my factories?
  user = Factory(:user)
  profile = user.profile
  lambda { 
    user.destroy
  }.should change(Artist, :count).by(-1)
end

评论/其他想法

如用户规范中的注释所述，使用Artist似乎很脆弱。如果我的工厂将来发生变化该怎么办？

也许我应该使用factory_girl回调并定义“艺术家用户”和“音乐家用户”？感谢所有输入。

Factory_Girl回调将使生活更加轻松。这样的事情怎么样？

Factory.define :user do |user|
  #attributes for user
end

Factory.define :artist do |artist|
  #attributes for artist
  artist.after_create {|a| Factory(:user, :profile => a)}
end

Factory.define :musician do |musician|
  #attributes for musician
  musician.after_create {|m| Factory(:user, :profile => m)}
end

尽管有一个公认的答案，但是这里有一些使用新语法的代码对我有用，对其他人可能有用。

spec / factories.rb

FactoryGirl.define do

  factory :musical_user, class: "User" do
    association :profile, factory: :musician
    #attributes for user
  end

  factory :artist_user, class: "User" do
    association :profile, factory: :artist
    #attributes for user
  end

  factory :artist do
    #attributes for artist
  end

  factory :musician do
    #attributes for musician
  end
end

规格/型号/artist_spec.rb

before(:each) do
  @artist = FactoryGirl.create(:artist_user)
end

这将创建艺术家实例以及用户实例。因此，您可以致电：

@artist.profile

获取Artist实例。

使用这样的特征；

FactoryGirl.define do
    factory :user do
        # attributes_for user
        trait :artist do
            association :profile, factory: :artist
        end
        trait :musician do
            association :profile, factory: :musician
        end
    end
end

现在您可以通过以下方式获取用户实例 FactoryGirl.create(:user, :artist)

您还可以使用嵌套工厂（继承）解决此问题，这样您可以为每个类创建一个基本工厂，然后嵌套从该基本父级继承的工厂。

FactoryGirl.define do
    factory :user do
        # attributes_for user
        factory :artist_profile do
            association :profile, factory: :artist
        end
        factory :musician_profile do
            association :profile, factory: :musician
        end
    end
end

现在，您可以访问嵌套工厂，如下所示：

artist_profile = create(:artist_profile)
musician_profile = create(:musician_profile)

希望这对某人有帮助。

看来工厂中的多态关联的行为与常规的Rails关联相同。

因此，如果您不在乎“ belongs_to”关联侧的模型属性（在此示例中为User），则还有另一种较为冗长的方法：

# Factories
FactoryGirl.define do
  sequence(:email) { Faker::Internet.email }

  factory :user do
    # you can predefine some user attributes with sequence
    email { generate :email }
  end

  factory :artist do
    # define association according to documentation
    user 
  end
end

# Using in specs    
describe Artist do      
  it 'created from factory' do
    # its more naturally to starts from "main" Artist model
    artist = FactoryGirl.create :artist        
    artist.user.should be_an(User)
  end
end

FactoryGirl关联：https : //github.com/thoughtbot/factory_girl/blob/master/GETTING_STARTED.md#associations

我目前正在使用此实现来处理中的多态关联 FactoryGirl：

在/spec/factories/users.rb中：

FactoryGirl.define do

  factory :user do
    # attributes for user
  end

  # define your Artist factory elsewhere
  factory :artist_user, parent: :user do
    profile { create(:artist) }
    profile_type 'Artist'
    # optionally add attributes specific to Artists
  end

  # define your Musician factory elsewhere
  factory :musician_user, parent: :user do
    profile { create(:musician) }
    profile_type 'Musician'
    # optionally add attributes specific to Musicians
  end

end

然后，照常创建记录： FactoryGirl.create(:artist_user)