FactoryGirl：ActiveRecord::AssociationTypeMismatch：用户预期，得到#<Class:0x007>答案

【问题标题】：FactoryGirl: ActiveRecord::AssociationTypeMismatch: User expected, got #<Class:0x007>FactoryGirl：ActiveRecord::AssociationTypeMismatch：用户预期，得到#<Class:0x007>
【发布时间】：2012-11-28 16:18:25
【问题描述】：

我有一个简单的 User 模型，带有一个 has_many :photos 关联。当我尝试FactoryGirl.create(:user) 时，我收到以下错误。有什么想法吗？

# user.rb
has_many :photos, dependent: :destroy

# photo.rb
belongs_to :user


FactoryGirl.define do
  factory :user do
    email 'john@site.com'
    after_build do |user|
      user.photos << FactoryGirl.build(:photo, user: user)
    end
  end

  factory :photo do
    photo File.new(File.join(::Rails.root.to_s, "/factories/images", "avatar1.jpg"), 'rb')
  end

错误输出。

ruby-1.9.2-p290 :015 > b = FactoryGirl.create(:user)
ActiveRecord::AssociationTypeMismatch: User(#70183166983920) expected, got #    <Class:0x007fa995612538>(#70183166186140)
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/activerecord-3.2.8/lib/active_record/associations/association.rb:204:in `raise_on_type_mismatch'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/activerecord-3.2.8/lib/active_record/associations/belongs_to_association.rb:6:in `replace'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/activerecord-3.2.8/lib/active_record/associations/singular_association.rb:17:in `writer'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/activerecord-3.2.8/lib/active_record/associations/builder/association.rb:51:in `block in define_writers'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/factory_girl-4.1.0/lib/factory_girl/attribute_assigner.rb:16:in `block (2 levels) in object'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/factory_girl-4.1.0/lib/factory_girl/attribute_assigner.rb:15:in `each'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/factory_girl-4.1.0/lib/factory_girl/attribute_assigner.rb:15:in `block in object'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/factory_girl-4.1.0/lib/factory_girl/attribute_assigner.rb:14:in `tap'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/factory_girl-4.1.0/lib/factory_girl/attribute_assigner.rb:14:in `object'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/factory_girl-4.1.0/lib/factory_girl/evaluation.rb:12:in `object'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/factory_girl-4.1.0/lib/factory_girl/strategy/build.rb:9:in `result'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/factory_girl-4.1.0/lib/factory_girl/factory.rb:42:in `run'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/factory_girl-4.1.0/lib/factory_girl/factory_runner.rb:23:in `block in run'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/activesupport-3.2.8/lib/active_support/notifications.rb:125:in `instrument'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/factory_girl-4.1.0/lib/factory_girl/factory_runner.rb:22:in `run'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/factory_girl-4.1.0/lib/factory_girl/strategy_syntax_method_registrar.rb:19:in `block in define_singular_strategy_method'
    ... 8 levels...
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/factory_girl-4.1.0/lib/factory_girl/attribute_assigner.rb:15:in `block in object'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/factory_girl-4.1.0/lib/factory_girl/attribute_assigner.rb:14:in `tap'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/factory_girl-4.1.0/lib/factory_girl/attribute_assigner.rb:14:in `object'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/factory_girl-4.1.0/lib/factory_girl/evaluation.rb:12:in `object'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/factory_girl-4.1.0/lib/factory_girl/strategy/create.rb:9:in `result'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/factory_girl-4.1.0/lib/factory_girl/factory.rb:42:in `run'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/factory_girl-4.1.0/lib/factory_girl/factory_runner.rb:23:in `block in run'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/activesupport-3.2.8/lib/active_support/notifications.rb:125:in `instrument'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/factory_girl-4.1.0/lib/factory_girl/factory_runner.rb:22:in `run'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/factory_girl-4.1.0/lib/factory_girl/strategy_syntax_method_registrar.rb:19:in `block in define_singular_strategy_method'
    from (irb):15
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/railties-3.2.8/lib/rails/commands/console.rb:47:in `start'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/railties-3.2.8/lib/rails/commands/console.rb:8:in `start'
    from /Users/user/.rvm/gems/ruby-1.9.2-p290@site/gems/railties-3.2.8/lib/rails/commands.rb:41:in `<top (required)>'
    from script/rails:6:in `require'
    from script/rails:6:in `<main>'ruby-1.9.2-p290 :016 > #<Class:0x007fa995612538>

【问题讨论】：

这个工作：user.photos
当前版本使用不同的格式定义回调，也许你应该在build之后使用而不是create之后使用
已解决。我应该使用较新的 after(:create) 而不是较旧的 after_build
@Martin 如果您发现错误，请回答您自己的问题。

标签： ruby-on-rails factory-bot

【解决方案1】：

解决了。我应该使用较新的 after(:create) 而不是较旧的 after_build。

【讨论】：

【解决方案2】：

我遇到了类似的问题，这是我用来解决它的代码块：

after(:create) do |user|
  user.photos << FactoryGirl.create :photo, user: user
end

【讨论】：

【解决方案3】：

我在验证 has_many 关联是否至少有一个关联模型时遇到了类似问题：

    class Classroom < ActiveRecord::Base
      # Relationships
      belongs_to :course
      has_many :weekdays

      # Validations
      validate :has_weekdays

      def has_weekdays
        errors.add(:base, 'it is invalid without at least one weekday') if   self.weekdays.blank?
      end

    end

所以，为了使工厂有效，这是我的代码

FactoryGirl.define do
  factory :classroom do
    course    

    after (:build) do |classroom|
      classroom.weekdays << FactoryGirl.create(:weekdays, classroom: classroom)
    end 
  end
end

【讨论】：