未定义的方法failure_app为零：NilClass

Question

我试图从Rails应用程序中使用devise来授予对Rack中间件内Sinatra应用程序的访问权限。

我的config/routes.rb中有：

authenticate "admin" do 
    mount Admins::Dashboard, :at => "/admins"                           
end 

在我的末日应用程序，我使用：

before do 
    env["warden"].authenticate!(:scope => "admin")                         
end 

get "/dashboard" do 
    erb :dashboard 
end 

现在，我得到一个错误，用下面的堆栈跟踪：

Started GET "/admins/dashboard" for 127.0.0.1 at 2012-10-11 08:45:13 +0200 

NoMethodError (undefined method `failure_app' for nil:NilClass): 
    devise (2.1.2) lib/devise/delegator.rb:11:in `failure_app' 
    devise (2.1.2) lib/devise/delegator.rb:5:in `call' 
    warden (1.2.1) lib/warden/manager.rb:130:in `call_failure_app' 
    warden (1.2.1) lib/warden/manager.rb:116:in `process_unauthenticated' 
    warden (1.2.1) lib/warden/manager.rb:47:in `call' 
    actionpack (3.2.8) lib/action_dispatch/middleware/best_standards_support.rb:17:in `call' 
    rack (1.4.1) lib/rack/etag.rb:23:in `call' 
    rack (1.4.1) lib/rack/conditionalget.rb:25:in `call' 

Answer 1

错误消息是关于自定义监护失败应用指向sinatra的缺失配置的投诉。

结账this previous answer和the related (detailed) blogpost about setting up Sinatra+Warden & Rails+Devise;希望那里的指导将帮助您成功实施解决方案。