ruby-on-rails - "Cannot redirect to nil!"

Question

我正在遵循 Michael Hartl 的 Rails 教程并进行一些小的调整。用户可以在他们的个人资料上发布微帖子(状态更新)，此时页面将重新加载并显示他们的新状态。我可以用手确认这完全按照预期工作。问题在于，尽管测试之外的最终结果看起来很完美，但由于某种原因，它的测试没有通过。

microposts_controller.rb、microposts_interface_test.rb(失败的测试)、相关错误消息和 users_controller.rb 的屏幕截图，按顺序排列:/image/RtONu.jpg

microposts_controller.rb

class MicropostsController < ApplicationController
  before_action :logged_in_user, only: [:create, :destroy]
  before_action :correct_user,   only: :destroy

  def create
    @micropost = current_user.microposts.build(micropost_params)
    if @micropost.save
      flash[:success] = "Status updated!"
      redirect_to @user
    else
      @feed_items = []
      flash[:warning] = "Status was blank!"
      redirect_to @user
    end
  end

  def destroy
    @micropost.destroy
    flash[:success] = "Status deleted."
    redirect_to @user
  end

microposts_interface_test.rb:

require 'test_helper'

class MicropostsInterfaceTest < ActionDispatch::IntegrationTest

  def setup
    @user = users(:mrtestit)
  end

  test "micropost interface" do
    log_in_as(@user)
    assert is_logged_in?
    # Invalid submission
    assert_no_difference 'Micropost.count' do
      post microposts_path, micropost: { content: "" }
    end
    # Valid submission
    content = "This status really ties the room together"
    assert_difference 'Micropost.count', 1 do
      post microposts_path, micropost: { content: content }
    end
    follow_redirect!
    assert_match content, response.body
    # Delete a post.
    assert_select 'a', text: 'delete'
    first_micropost = @user.microposts.paginate(page: 1).first
    assert_difference 'Micropost.count', -1 do
      delete micropost_path(first_micropost)
    end
    # Visit a different user.
    get user_path(users(:archer))
    assert_select 'a', text: 'delete', count: 0
  end

end

users_controller.rb:

class UsersController < ApplicationController
  before_action :logged_in_user, only: [:index, :edit, :update, :destroy]
  before_action :correct_user, only: [:edit, :update]
  before_action :admin_user, only: :destroy

  def index
    @users = User.where(activated: true).paginate(page: params[:page])
  end

  def show
    @user = User.find(params[:id])
    if logged_in?
      @micropost = current_user.microposts.build
      @feed_items = current_user.feed.paginate(page: params[:page])
    end
    @microposts = @user.microposts.paginate(page: params[:page])
    redirect_to root_url and return unless @user.activated?
  end

我理解，出于某种原因，这意味着 @user 是 nil。不过，我已经多次确认 redirect_to @user 在其他地方都有效。

所有其他测试都通过的事实已经证明了这一点，但为了加倍努力，我已经确认失败的 redirect_to @user 代码行可以在其他文件中工作，例如例如，当用户在其设置页面下更新其个人资料信息，然后重定向到其个人资料页面时。我已经花了 10 多个小时来处理这个问题(大部分是昨天)，并且即将删除这个测试并继续我的生活。 Stackoverflow 是我最后的手段。

Answer 1

我认为你必须改变

redirect_to @user

至

redirect_to current_user

@user 是类实例变量，必须手动创建，例如:

@user = User.find_by_id post.owner_id

而current_user是全局变量，可以在任何地方使用。但不要忘记将其检查为零，因为用户无法登录!

您可以在每个方法中通过 unless current_user.nil? 手动检查它，或者更好地添加辅助方法并在 Controller 中使用它，教程已经描述了这种方式:

module SessionHelper
    def signed_in_user
        unless signed_in?
          store_location
          redirect_to signin_url, notice: "Please sign in."
        end
    end
# ...

class MicropostsController < ApplicationController
    before_action :signed_in_user
# ...

更新:Aleks 的建议:如果您想重定向到可能不是当前用户的帖子所有者，请使用

user = micropost.owner
redirect_to user