undefined метод `follow 'for nil: NilClass

Question

Я работаю над проектом, похожим на твитерский клон. Однако я столкнулся с ошибкой, которая заключается в следующем: undefined method `follow 'for nil: NilClass в моем контроллере. Итак, для начала, вот мой контроллер:

class EpicenterController < ApplicationController 

def feed 
#Here we initialize the array that will hold tweets from the current_user's  
    following list. 
@following_tweets = [] 

    Tweet.all.each do |tweet| 
    if current_user.following.include?(tweet.user_id) 
    @following_tweets.push(tweet) 
    end 
    end 
end 

def show_user 
    @user = User.find(params[:id]) 
end 

def now_following 
    @user = User.find(params[:follow_id]) 

    #Adding the user.id of the user you want to follow to your 'follow' array 
    attribute 
    current_user.following.push(params[:follow_id].to_i) 

    current_user.save 
end 

def unfollow 
end 

конец

Вот моя модель:

class User < ActiveRecord::Base 
# Include default devise modules. Others available are: 
# :confirmable, :lockable, :timeoutable and :omniauthable 
    devise :database_authenticatable, :registerable, 
    :recoverable, :rememberable, :trackable, :validatable 

    serialize :following, Array  
    has_many :tweets 

    validates :username, presence: true, uniqueness: true 
end 

Моя схема:

ActiveRecord::Schema.define(version: 20160811164903) do 

create_table "tweets", force: :cascade do |t| 
    t.string "message" 
    t.integer "user_id" 
    t.datetime "created_at", null: false 
    t.datetime "updated_at", null: false 
end 

create_table "users", force: :cascade do |t| 
    t.string "email",     default: "", null: false 
    t.string "encrypted_password",  default: "", null: false 
    t.string "reset_password_token" 
    t.datetime "reset_password_sent_at" 
    t.datetime "remember_created_at" 
    t.integer "sign_in_count",   default: 0, null: false 
    t.datetime "current_sign_in_at" 
    t.datetime "last_sign_in_at" 
    t.string "current_sign_in_ip" 
    t.string "last_sign_in_ip" 
    t.datetime "created_at",       null: false 
    t.datetime "updated_at",       null: false 
    t.string "name" 
    t.string "username" 
    t.text  "bio" 
    t.string "location" 
    t.text  "following" 
end 

add_index "users", ["email"], name: "index_users_on_email", unique: true 
add_index "users", ["reset_password_token"], name:  
"index_users_on_reset_password_token", unique: true 

end 

Наконец мой контроллер приложения:

class ApplicationController < ActionController::Base 
    # Prevent CSRF attacks by raising an exception. 
    # For APIs, you may want to use :null_session instead. 
    protect_from_forgery with: :exception 

    before_action :configure_permitted_parameters, if: :devise_controller? 

    protected 

    def configure_permitted_parameters 

    devise_parameter_sanitizer.permit(:sign_up, keys: [:name, :username, 
    :bio,  
    :location, :following]) 

    devise_parameter_sanitizer.permit(:account_update, keys: [:name, 
    :username, :bio, :location, :following]) 
    end 
end 

Благодарим за помощь, которая может быть оказана. Пожалуйста, дайте мне знать, если вам нужно увидеть что-то еще, и я добавлю.

Трассировка стека:

NoMethodError (undefined method `following' for nil:NilClass): 
app/controllers/epicenter_controller.rb:8:in `block in feed' 
app/controllers/epicenter_controller.rb:7:in `feed' 


Rendered /Users/mikecuddy/.rvm/rubies/ruby- 
2.2.1/lib/ruby/gems/2.2.0/gems/actionpack- 
4.2.6/lib/action_dispatch/middleware/templates/rescues/_source.erb (3.9ms) 
Rendered /Users/mikecuddy/.rvm/rubies/ruby- 
2.2.1/lib/ruby/gems/2.2.0/gems/actionpack- 
4.2.6/lib/action_dispatch/middleware/templates/rescues/_trace.html.erb  
(2.7ms) 
Rendered /Users/mikecuddy/.rvm/rubies/ruby- 
2.2.1/lib/ruby/gems/2.2.0/gems/actionpack- 
4.2.6/lib/action_dispatch/middleware/templates/rescues/_request_and_response.html.erb (0.9ms) 
Rendered /Users/mikecuddy/.rvm/rubies/ruby- 
2.2.1/lib/ruby/gems/2.2.0/gems/actionpack- 
4.2.6/lib/action_dispatch/middleware/templates/rescues/diagnostics.html.erb 
within rescues/layout (63.4ms) 
Rendered /Users/mikecuddy/.rvm/rubies/ruby- 
2.2.1/lib/ruby/gems/2.2.0/gems/web-console- 
2.3.0/lib/web_console/templates/_markup.html.erb (0.4ms) 
Rendered /Users/mikecuddy/.rvm/rubies/ruby- 
2.2.1/lib/ruby/gems/2.2.0/gems/web-console- 
2.3.0/lib/web_console/templates/_inner_console_markup.html.erb within 
layouts/inlined_string (0.3ms) 
Rendered /Users/mikecuddy/.rvm/rubies/ruby- 
2.2.1/lib/ruby/gems/2.2.0/gems/web-console- 
2.3.0/lib/web_console/templates/_prompt_box_markup.html.erb within  
layouts/inlined_string (0.3ms) 
Rendered /Users/mikecuddy/.rvm/rubies/ruby- 
2.2.1/lib/ruby/gems/2.2.0/gems/web-console- 
2.3.0/lib/web_console/templates/style.css.erb within layouts/inlined_string 
(0.5ms) 
Rendered /Users/mikecuddy/.rvm/rubies/ruby- 
2.2.1/lib/ruby/gems/2.2.0/gems/web-console- 
2.3.0/lib/web_console/templates/console.js.erb within layouts/javascript 
(62.0ms) 
Rendered /Users/mikecuddy/.rvm/rubies/ruby- 
2.2.1/lib/ruby/gems/2.2.0/gems/web-console- 
2.3.0/lib/web_console/templates/main.js.erb within layouts/javascript 
(0.3ms) 
Rendered /Users/mikecuddy/.rvm/rubies/ruby- 
2.2.1/lib/ruby/gems/2.2.0/gems/web-console- 
2.3.0/lib/web_console/templates/error_page.js.erb within layouts/javascript 
(0.6ms) 
Rendered /Users/mikecuddy/.rvm/rubies/ruby- 
2.2.1/lib/ruby/gems/2.2.0/gems/web-console- 
2.3.0/lib/web_console/templates/index.html.erb (139.5ms) 

Answer 1

current_user является nil для не зарегистрированных пользователей, так что вам нужно, чтобы справиться с этим:

if user_signed_in? 
    current_user.following # ... 
else 
    store_location_for :user, request.path 
    redirect_to new_user_session_path, alert: 'You need to be logged in to do that.' 
end 

или

class EpicenterController < ApplicationController 
    before_action :authenticate_user! #, only: [:feed, :now_following] (optional) 
    # ... 
end 

если ваш контроллер в основном предназначен для подписываемых пользователей (что похоже на это).