Question

我收到了这2个错误，我不知道如何修复它们。我遇到的一个问题是新版教程和旧版本（rails 4和3.2之间的区别）之间的差异。

我的规格是：

Ruby版本：1.9.2p320

Rails版本：3.2.13

Rspec：2.11.1

计算机：Macbook Pro OS X Mountain Lion

错误

  1) User following and unfollowing 
     Failure/Error: before { @user.unfollow!(other_user) }
     NoMethodError:
       undefined method `find_by' for []:ActiveRecord::Relation
     # ./app/models/user.rb:36:in `unfollow!'
     # ./spec/models/user_spec.rb:47:in `block (4 levels) in <top (required)>'

  2) User following and unfollowing followed_users 
     Failure/Error: before { @user.unfollow!(other_user) }
     NoMethodError:
       undefined method `find_by' for []:ActiveRecord::Relation
     # ./app/models/user.rb:36:in `unfollow!'
     # ./spec/models/user_spec.rb:47:in `block (4 levels) in <top (required)>'

User.rb

  def following?(other_user)
    relationships.where(followed_id: other_user.id).first
  end

  def follow!(other_user)
    relationships.create!(followed_id: other_user.id)
  end

  def unfollow!(other_user)
    relationships.find_by(followed_id: other_user.id).destroy!
  end

user_spec.rb

describe "following" do
    let(:other_user) { FactoryGirl.create(:user) }
    before do
      @user.save
      @user.follow!(other_user)
    end

    it { should be_following(other_user) }
    its(:followed_users) { should include(other_user) }

    describe "followed users" do 
      subject { other_user }
      its(:followers) {should include(@user) } 
    end

    describe "and unfollowing" do
      before { @user.unfollow!(other_user) }

      it {should_not be_following(other_user) }
      its(:followed_users) {should_not include(other_user) }
    end
  end

Answer 1

当您使用它时，

find_by在Rails 3中不存在.Rails 3为此使用了method_missing，因此使用find_by_followed_id将起作用。

我建议使用Hartl的Rails 3 tutorial。

Answer 2

尝试：

def unfollow!(other_user)
  relationships.find_by_followed_id(other_user.id).destroy!
end

Answer 3

作为FYI，使用rails 4不推荐使用find_by_X方法。所有查询现在都是Model.find（属性：“attribute”）

Michael Hartl教程第11章中的“未定义方法`find_by'”

3 个答案: