ActiveModel::SecurePassword:Module 的未定义方法“min_cost”

Question

我正在关注 Michale harlt 的 ruby​​ on rails 教程。一切都很顺利，直到我遇到了这个问题，在输入用户名和密码并单击“登录”按钮后，我收到了一个错误 ” ActiveModel::SecurePassword:Module 的未定义方法 `min_cost'"。我正在尝试从过去 2 天开始解决此问题，但无法找到任何相关的解决方案。 请帮我解决这个问题。提前致谢。这是我所有相关的项目文件。 （我正在使用导轨 3.2.16） 如需更多信息，请告诉我。

用户.rb

class User < ActiveRecord::Base
attr_accessor :remember_token
before_save { self.email = email.downcase }
validates :name,  presence: true, length: { maximum: 50 }
VALID_EMAIL_REGEX = /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i
validates :email, presence: true, length: { maximum: 255 },
                format: { with: VALID_EMAIL_REGEX },
                uniqueness: { case_sensitive: false }
has_secure_password
validates :password, length: { minimum: 6 }

# Returns the hash digest of the given string.
def User.digest(string)
cost = ActiveModel::SecurePassword.min_cost ? BCrypt::Engine::MIN_COST :
                                                 BCrypt::Engine.cost
BCrypt::Password.create(string, cost: cost)
end

# Returns a random token.
def User.new_token
SecureRandom.urlsafe_base64
end

# Remembers a user in the database for use in persistent sessions.
def remember
self.remember_token = User.new_token
update_attribute(:remember_digest, User.digest(remember_token))
end

# Returns true if the given token matches the digest.
def authenticated?(remember_token)
BCrypt::Password.new(remember_digest).is_password?(remember_token)
end
end

sessions_helper.rb

module SessionsHelper

# Logs in the given user.
def log_in(user)
 session[:user_id] = user.id
 end

 # Remembers a user in a persistent session.
 def remember(user)
 user.remember
 cookies.permanent.signed[:user_id] = user.id
 cookies.permanent[:remember_token] = user.remember_token
 end

 # Returns the user corresponding to the remember token cookie.
 def current_user
  if (user_id = session[:user_id])
  @current_user ||= User.find_by_id(user_id)
  elsif (user_id = cookies.signed[:user_id])
  user = User.find_by_id(user_id)
  if user && user.authenticated?(cookies[:remember_token])
    log_in user
    @current_user = user
  end
  end
  end

  # Returns true if the user is logged in, false otherwise.
  def logged_in?
  !current_user.nil?
  end

  # Log Out Current User
  def log_out
   session.delete(:user_id)
   @current_user = nil
   end
  end

sessions_controller.rb

    class SessionsController < ApplicationController

   def new
   end

   def create
   user = User.find_by_email(params[:session][:email].downcase)
   if user && user.authenticate(params[:session][:password])
   log_in user
   remember user
   redirect_to user
   else
   flash.now[:danger] = 'Invalid email/password combination'
   render 'new'
   end
end

  def destroy
  log_out
  redirect_to home_path
  end
end

宝石文件

    source 'https://rubygems.org'

gem 'rails', '3.2.16'
    gem 'bcrypt-ruby', '~> 3.1.2'
    gem 'strong_parameters'



    # Bundle edge Rails instead:
# gem 'rails', :git => 'git://github.com/rails/rails.git'

group :development, :test do    
  gem 'sqlite3',     '1.3.9'
      gem 'guard'


     end

group :test do
  gem 'minitest-reporters'   
  gem 'mini_backtrace',     '0.1.3'
  gem 'guard-minitest',     '2.3.1'
end

group :production do
  gem 'pg',             '0.17.1'
  gem 'rails_12factor', '0.0.2'
      gem 'puma',           '2.11.1'

end


# Gems used only for assets and not required
# in production environments by default.
group :assets do

  gem 'coffee-rails', '~> 3.2.1'
      gem 'sass-rails', '>= 3.2'
      gem 'bootstrap-sass', '~> 3.3.4'
      gem 'sprockets-rails', '=2.0.0.backport1'
      gem 'sprockets', github: 'tessi/sprockets', branch: '2_2_2_backport2'


  # See https://github.com/sstephenson/execjs#readme for more supported runtimes
  # gem 'therubyracer', :platforms => :ruby

  gem 'uglifier', '>= 1.0.3'
end

gem 'jquery-rails'

# To use ActiveModel has_secure_password
# gem 'bcrypt-ruby', '~> 3.0.0'

# To use Jbuilder templates for JSON
# gem 'jbuilder'

# Use unicorn as the app server
# gem 'unicorn'

# Deploy with Capistrano
# gem 'capistrano'

# To use debugger
# gem 'debugger'

应用程序跟踪

    app/models/user.rb:14:in `digest'
    app/models/user.rb:27:in `remember'
    app/helpers/sessions_helper.rb:10:in `remember'
    app/controllers/sessions_controller.rb:10:in `create'        

Answer 1

据我所知，SecurePassword#min_cost 出现在 rails4（或 rails3 > 3.2.16）

由于您只是在学习，我的建议是不要专注于解决这个特定错误，而只需将有问题的行替换为：

cost = BCrypt::Engine::MIN_COST

甚至与

cost = 10

然后走得更远。无论您是否仍要解决此问题，您都应该将您的 rails 升级到 4 个（或引入此方法的任何版本。）