devise_error_messages！对nil：NilClass导致未定义的方法`errors' [英] devise_error_messages! causes undefined method `errors' for nil:NilClass

问题描述

我在我的布局/ application.html.erb上有一个表单，该表格在下面发布，如果我添加了<％= devise_error_messages！ ％> 我得到以下错误。

我如何添加devise_error_messages而不分页？

/app/views/layouts/application.html.erb

 <％= form_for资源，：as => resource_name，：url => registration_path（resource_name））do | f | ％GT; 
<％= devise_error_messages！ ％GT; <！ - 这一行导致问题 - > 
< h3>添加新联系人< / h3> 
名字< br /> 
<％= f.text_field：username％>< br /> 
姓氏< br /> 
<％= f.text_field：password％>< br /> 
<％= f.text_field：password_confirmation％>< br /> 
电子邮件< br /> 
<％= f.text_field：email％> 
< hr /> 
<％= f.submit添加联系人％> 
 
<％end％> 
  

错误：

 code> My_devise / sessions中的NoMethodError＃index 
 
显示/app/views/layouts/application.html.erb，其中第59行提出：
 
 undefined方法`错误'为nil：NilClass 
 
提取源（围绕行＃59）：
 
 56：< a href =＃class =has-popupballoon button button-蓝色>< span class =add>< / span>新联系人< / a> 
 57：< div class =popupballoon top> 
 58：<％= form_for（resource，：as => resource_name，：url => registration_path（resource_name））do | f | ％GT; 
 59：<％= devise_error_messages！ ％GT; 
 60：< h3>添加新的联系人< / h3> 
 61：名字< br /> 
 62：<％= f.text_field：username％>< br /> 
  

这是我使用的网址 http：// localhost：3000 / admin / home ，这里是我的routes.rb

  devise_for：users do 
 get '/ users / sign_out'=> 'devise / sessions＃destroy'
 get/ users / sign_in，：to => my_devise / sessions＃new
 get'admin / home'，：to => 'my_devise / sessions＃index'
 get'users / sign_up'，：to => 'my_devise / registrationments＃new'
 end 
 
 devise_for：users，：controllers => {：sessions => my_devise / sessions，：registrations => my_devise / registrations} 
 gethome / index
 root：to => home＃index
  

/app/controllers/my_devise/sessions_controller.rb

  class MyDevise :: SessionsController< Devise :: SessionsController 
 layout false 
 
 before_filter：authenticate_user！ 
 
 def index 
 render：layout => 'application'
 end 
 
 def new 
 super 
 end 
 
 def create 
 super 
 end 
 
 end 
  

/app/controllers/my_devise/registrations_controller.rb

  class MyDevise :: RegistrationsController< Devise :: RegistrationsController 
 
 def index 
 
 end 
 
 end 
  

耙路线：

  users_sign_out GET /users/sign_out(.:format）{ ：controller =>devise / sessions，：action =>destroy} 
 users_sign_in GET /users/sign_in(.:format）{：controller =>my_devise / sessions，：action = >new} 
 admin_home GET /admin/home(.:format）{：controller =>my_devise / sessions，：action =>index} 
 users_sign_up GET / users /sign_up(.:format）{：controller =>my_devise / registrations，：action =>new} 
 new_user_session GET /users/sign_in(.:format）{：action =>新的，：controller =>devise / sessions} 
 user_session POST /users/sign_in(.:format）{：action =>create，：controller =>devise / sessions} 
 destroy_user_session DELETE /users/sign_out(.:format）{：action =>destroy ，：controller =>devise / sessions} 
 user_password POST /users/password(.:format）{：action =>create，：controller =>devise / passwords} 
 new_user_password GET /users/password/new(.:format）{：action =>new，：controller =>devise / passwords} 
 edit_user_password GET / users / password / edit 。：format）{：action =>edit，：controller =>devise / passwords} 
 PUT /users/password(.:format）{：action =>update controller =>devise / passwords} 
 cancel_user_registration GET /users/cancel(.:format）{：action =>cancel，：controller =>devise / registrations} 
 user_registration POST /users(.:format）{：action =>create，：controller =>devise / registrations} 
 new_user_registration GET /users/sign_up(.:format）{：action => ;new，：controller =>devise / registrations} 
 edit_user_registration GET /users/edit(.:format）{ ：action =>edit，：controller =>devise / registrations} 
 PUT /users(.:format）{：action =>update，：controller =>devise /注册} 
 DELETE /users(.:format）{：action =>destroy，：controller =>devise / registrations} 
 new_user_session GET /users/sign_in(.:format ）{：action =>new，：controller =>my_devise / sessions} 
 POST /users/sign_in(.:format）{：action =>create，：controller => ;my_devise / sessions} 
 destroy_user_session DELETE /users/sign_out(.:format）{：action =>destroy，：controller =>my_devise / sessions} 
 POST / users /password(.:format）{：action =>create，：controller =>devise / passwords} 
 GET /users/password/new(.:format）{：action => new，：controller =>devise / passwords} 
 GET / use rs / password / edit（。：format）{：action =>edit，：controller =>devise / passwords} 
 PUT /users/password(.:format）{：action => ;update，：controller =>devise / passwords} 
 GET /users/cancel(.:format）{：action =>cancel，：controller =>my_devise / registrations } 
 POST /users(.:format）{：action =>create，：controller =>my_devise / registrations} 
 GET /users/sign_up(.:format）{： action =>new，：controller =>my_devise / registrations} 
 GET /users/edit(.:format）{：action =>edit，：controller =>my_devise / registration} 
 PUT /users(.:format）{：action =>update，：controller =>my_devise / registrations} 
 DELETE /users(.:format）{ ：action =>destroy，：controller =>my_devise / regis trations} 
 home_index GET /home/index(.:format）{：controller =>home，：action =>index} 
 root / {：controller => home，：action =>index} 
 root / {：controller =>home，：action =>index} 
  pre> 
 
解决方案
重新审视项目我没有时间触摸一段时间，但简单的答案只是为了创建user_controller中的用户对象。 
 
 
 
我将此片段添加到application_controller中：
  before_filter：instantiateUser 
 
 def instantiateUser 
 @user = User.new 
 end 
  
 
I have a form on my layouts/application.html.erb that is posted below and and if i add the line <%= devise_error_messages! %> I get the error below.

How can i add the devise_error_messages without having the page break?

/app/views/layouts/application.html.erb
<%= form_for(resource, :as => resource_name, :url => registration_path(resource_name)) do |f| %>
    <%= devise_error_messages! %>  <!-- this line causes issues -->
    <h3>Add new contact</h3>
    First Name<br />
    <%= f.text_field :username %><br />
    Last Name<br />
    <%= f.text_field :password %><br />
    <%= f.text_field :password_confirmation %><br />                                
    Email<br />
    <%= f.text_field :email %>
    <hr />
    <%= f.submit "Add Contact" %>

<% end %>
Error:
NoMethodError in My_devise/sessions#index

Showing /app/views/layouts/application.html.erb where line #59 raised:

undefined method `errors' for nil:NilClass

Extracted source (around line #59):

56:                             <a href="#" class="has-popupballoon button button-blue"><span class="add"></span>New Contact</a>
57:                             <div class="popupballoon top">
58:                             <%= form_for(resource, :as => resource_name, :url => registration_path(resource_name)) do |f| %>
59:   <%= devise_error_messages! %>
60:                                 <h3>Add new contact</h3>
61:                                 First Name<br />
62:                                 <%= f.text_field :username %><br />
This is the url i'm using http://localhost:3000/admin/home and here's my routes.rb
devise_for :users do 
    get '/users/sign_out' => 'devise/sessions#destroy' 
    get "/users/sign_in", :to => "my_devise/sessions#new"
    get 'admin/home', :to => 'my_devise/sessions#index'
    get 'users/sign_up', :to => 'my_devise/registrations#new'
  end 

  devise_for :users, :controllers => {:sessions => "my_devise/sessions", :registrations => "my_devise/registrations"}
  get "home/index"
  root :to => "home#index"
/app/controllers/my_devise/sessions_controller.rb
class MyDevise::SessionsController < Devise::SessionsController
    layout false

    before_filter :authenticate_user!

    def index
        render :layout => 'application'
    end

    def new
        super
    end

    def create
        super
    end

end
/app/controllers/my_devise/registrations_controller.rb
class MyDevise::RegistrationsController < Devise::RegistrationsController

    def index

    end

end
Rake routes:
users_sign_out GET    /users/sign_out(.:format)      {:controller=>"devise/sessions", :action=>"destroy"}
           users_sign_in GET    /users/sign_in(.:format)       {:controller=>"my_devise/sessions", :action=>"new"}
              admin_home GET    /admin/home(.:format)          {:controller=>"my_devise/sessions", :action=>"index"}
           users_sign_up GET    /users/sign_up(.:format)       {:controller=>"my_devise/registrations", :action=>"new"}
        new_user_session GET    /users/sign_in(.:format)       {:action=>"new", :controller=>"devise/sessions"}
            user_session POST   /users/sign_in(.:format)       {:action=>"create", :controller=>"devise/sessions"}
    destroy_user_session DELETE /users/sign_out(.:format)      {:action=>"destroy", :controller=>"devise/sessions"}
           user_password POST   /users/password(.:format)      {:action=>"create", :controller=>"devise/passwords"}
       new_user_password GET    /users/password/new(.:format)  {:action=>"new", :controller=>"devise/passwords"}
      edit_user_password GET    /users/password/edit(.:format) {:action=>"edit", :controller=>"devise/passwords"}
                         PUT    /users/password(.:format)      {:action=>"update", :controller=>"devise/passwords"}
cancel_user_registration GET    /users/cancel(.:format)        {:action=>"cancel", :controller=>"devise/registrations"}
       user_registration POST   /users(.:format)               {:action=>"create", :controller=>"devise/registrations"}
   new_user_registration GET    /users/sign_up(.:format)       {:action=>"new", :controller=>"devise/registrations"}
  edit_user_registration GET    /users/edit(.:format)          {:action=>"edit", :controller=>"devise/registrations"}
                         PUT    /users(.:format)               {:action=>"update", :controller=>"devise/registrations"}
                         DELETE /users(.:format)               {:action=>"destroy", :controller=>"devise/registrations"}
        new_user_session GET    /users/sign_in(.:format)       {:action=>"new", :controller=>"my_devise/sessions"}
                         POST   /users/sign_in(.:format)       {:action=>"create", :controller=>"my_devise/sessions"}
    destroy_user_session DELETE /users/sign_out(.:format)      {:action=>"destroy", :controller=>"my_devise/sessions"}
                         POST   /users/password(.:format)      {:action=>"create", :controller=>"devise/passwords"}
                         GET    /users/password/new(.:format)  {:action=>"new", :controller=>"devise/passwords"}
                         GET    /users/password/edit(.:format) {:action=>"edit", :controller=>"devise/passwords"}
                         PUT    /users/password(.:format)      {:action=>"update", :controller=>"devise/passwords"}
                         GET    /users/cancel(.:format)        {:action=>"cancel", :controller=>"my_devise/registrations"}
                         POST   /users(.:format)               {:action=>"create", :controller=>"my_devise/registrations"}
                         GET    /users/sign_up(.:format)       {:action=>"new", :controller=>"my_devise/registrations"}
                         GET    /users/edit(.:format)          {:action=>"edit", :controller=>"my_devise/registrations"}
                         PUT    /users(.:format)               {:action=>"update", :controller=>"my_devise/registrations"}
                         DELETE /users(.:format)               {:action=>"destroy", :controller=>"my_devise/registrations"}
              home_index GET    /home/index(.:format)          {:controller=>"home", :action=>"index"}
                    root        /                              {:controller=>"home", :action=>"index"}
                    root        /                              {:controller=>"home", :action=>"index"}

解决方案
Revisiting a project I haven't had time to touch in a while, but the simple answer was just to create the User object in the application_controller. 

I added this snippet to the application_controller:
before_filter :instantiateUser

def instantiateUser
    @user = User.new
end


                        
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