ruby-on-rails - OmniAuth/Rails - 当你没有想到它时你有一个 nil 对象

Question

我的 Rails 应用程序出现以下错误，我不知道如何调试或修复它:

NoMethodError in AuthenticationsController#create

You have a nil object when you didn't expect it! You might have expected an instance of ActiveRecord::Base. The error occurred while evaluating nil.[]

Rails.root: /Users/phil/Sites/travlrapp.com Application Trace | Framework Trace | Full Trace

app/controllers/authentications_controller.rb:15:in `create'

Controller 是这样的:

class AuthenticationsController < ApplicationController
  def index
    @authentications = current_user.authentications if current_user
  end

    def create

        omniauth = request.env["omniauth.auth"]

        unless omniauth
            redirect_to authentications_url
            flash[:notice] = "Could not authenticate via #{params['provider']}."
        end

        authentication = Authentication.find_by_provider_and_uid(omniauth['provider'], omniauth['uid'])
        if authentication
            flash[:notice] = "Signed in successfully."
            sign_in_and_redirect(:user, authentication.user)
        elsif current_user

            current_user.authentications.create!(:provider => omniauth['provider'], :uid => omniauth['uid'], :token => omniauth['credentials']['token'], :secret => omniauth['credentials']['secret'])
            flash[:notice] = "Authentication successful."
            redirect_to authentications_url
        else
            user = User.new
            user.apply_omniauth(omniauth)
            if user.save
                flash[:notice] = "Signed in successfully."
                sign_in_and_redirect(:user, user)
            else
                session[:omniauth] = omniauth.except('extra')
                redirect_to new_user_registration_url
            end
        end
    end


  def destroy
    @authentication = current_user.authentications.find(params[:id])
    @authentication.destroy
    flash[:notice] = "Successfully destroyed authentication."
    redirect_to authentications_url
  end
end

OmniAuth 过去工作正常，然后我把它搞砸了，试图换成支持 flickr 的 pchilton 的 fork 。我通过在 gemfile 中设置 :git => 并尝试重新安装来做到这一点，但我不确定我是否做对了。

我现在已经手动删除了所有 omniauth 和 oafoo gem 文件，并首先安装了当前稳定版 (0.1.6) 和 git 主副本，但所有错误都是一样的。

真的很茫然，我认识的人都不知道问题出在哪里。

Answer 1

omniauth 很可能是nil。当您使用 unless onmniauth 检查 nil 时，redirect_to 实际上并没有停止执行下面的 Controller 代码。

你可能想要这样的东西:

unless omniauth
  redirect_to authentications_url
  flash[:notice] = "Could not authenticate via #{params['provider']}."
  return
end

现在，您仍然需要弄清楚为什么 omniauth 是 nil。为此，请查看 README 以确保您正确使用了 OmniAuth。 . /auth/provider/callback 是否路由到 AuthenticationsController#create ？