ruby – “未定义的方法”变为’nil：NilClass’,它不应该

unless resource.nil?
  resource = resource.becomes(Accounts::Admin)
end

这引起了一个错误

undefined method `becomes’ for nil:NilClass

如果我这样做

unless resource.nil?
  a = resource.becomes(Accounts::Admin)
  resource = a
end

一切顺利.

如果首先执行=运算符的右边部分,有什么区别？

编辑：

发生了令人讨厌的事情,if if下的最后一行正在执行,但“ALOHA”从未打印过.

<%
puts "AAAA #{resource.inspect}"
if false
    puts "ALOHA"

    # this line is being executed !
    # if I comment it out the BBBB output is correct
    resource = nil
end 
puts "BBBB #{resource.inspect}"
%>

它打印

AAAA User id: nil,nome: nil,endereco_id: nil,created_at: nil,
updated_at: nil,email: “”

BBBB nil

但如果我这样做

<%
res = resource

puts "AAAA #{res.inspect}"
if false
  puts "ALOHA"
  res = nil
end 
puts "BBBB #{res.inspect}"
%>

它打印正确

AAAA User id: nil,email: “”

BBBB User id: nil,
endereco_id: nil,updated_at: nil,email: “”

我已经尝试重启服务器了.此代码段位于devise / registrations / new.html.erb. resourcevariable应该是User的一个实例,由devise的RegistrationController创建

我已经检查了隐藏字符的文本,我粘贴的片段是正在测试的文件的整个文本.

这是@/.rvm/gems/ruby-2.3.3@mygem/gems/devise-4.2.0/app/controllers/devise/registrations_controller.rb中控制器的内容.

class Devise::RegistrationsController < DeviseController
  prepend_before_action :require_no_authentication,only: [:new,:create,:cancel]
  prepend_before_action :authenticate_scope!,only: [:edit,:update,:destroy]
  prepend_before_action :set_minimum_password_length,:edit]

  # GET /resource/sign_up
  def new
    build_resource({})
    yield resource if block_given?
    respond_with resource
  end

  # POST /resource
  def create
    build_resource(sign_up_params)

    resource.save
    yield resource if block_given?
    if resource.persisted?
      if resource.active_for_authentication?
        set_flash_message! :notice,:signed_up
        sign_up(resource_name,resource)
        respond_with resource,location: after_sign_up_path_for(resource)
      else
        set_flash_message! :notice,:"signed_up_but_#{resource.inactive_message}"
        expire_data_after_sign_in!
        respond_with resource,location: after_inactive_sign_up_path_for(resource)
      end
    else
      clean_up_passwords resource
      set_minimum_password_length
      respond_with resource
    end
  end

  # GET /resource/edit
  def edit
    render :edit
  end

  # PUT /resource
  # We need to use a copy of the resource because we don't want to change
  # the current user in place.
  def update
    self.resource = resource_class.to_adapter.get!(send(:"current_#{resource_name}").to_key)
    prev_unconfirmed_email = resource.unconfirmed_email if resource.respond_to?(:unconfirmed_email)

    resource_updated = update_resource(resource,account_update_params)
    yield resource if block_given?
    if resource_updated
      if is_flashing_format?
        flash_key = update_needs_confirmation?(resource,prev_unconfirmed_email) ?
          :update_needs_confirmation : :updated
        set_flash_message :notice,flash_key
      end
      bypass_sign_in resource,scope: resource_name
      respond_with resource,location: after_update_path_for(resource)
    else
      clean_up_passwords resource
      respond_with resource
    end
  end

  # DELETE /resource
  def destroy
    resource.destroy
    Devise.sign_out_all_scopes ? sign_out : sign_out(resource_name)
    set_flash_message! :notice,:destroyed
    yield resource if block_given?
    respond_with_navigational(resource){ redirect_to after_sign_out_path_for(resource_name) }
  end

  # GET /resource/cancel
  # Forces the session data which is usually expired after sign
  # in to be expired now. This is useful if the user wants to
  # cancel oauth signing in/up in the middle of the process,# removing all OAuth session data.
  def cancel
    expire_data_after_sign_in!
    redirect_to new_registration_path(resource_name)
  end

  protected

  def update_needs_confirmation?(resource,previous)
    resource.respond_to?(:pending_reconfirmation?) &&
      resource.pending_reconfirmation? &&
      previous != resource.unconfirmed_email
  end

  # By default we want to require a password checks on update.
  # You can overwrite this method in your own RegistrationsController.
  def update_resource(resource,params)
    resource.update_with_password(params)
  end

  # Build a devise resource passing in the session. Useful to move
  # temporary session data to the newly created user.
  def build_resource(hash=nil)
    self.resource = resource_class.new_with_session(hash || {},session)
  end

  # Signs in a user on sign up. You can overwrite this method in your own
  # RegistrationsController.
  def sign_up(resource_name,resource)
    sign_in(resource_name,resource)
  end

  # The path used after sign up. You need to overwrite this method
  # in your own RegistrationsController.
  def after_sign_up_path_for(resource)
    after_sign_in_path_for(resource)
  end

  # The path used after sign up for inactive accounts. You need to overwrite
  # this method in your own RegistrationsController.
  def after_inactive_sign_up_path_for(resource)
    scope = Devise::Mapping.find_scope!(resource)
    router_name = Devise.mappings[scope].router_name
    context = router_name ? send(router_name) : self
    context.respond_to?(:root_path) ? context.root_path : "/"
  end

  # The default url to be used after updating a resource. You need to overwrite
  # this method in your own RegistrationsController.
  def after_update_path_for(resource)
    signed_in_root_path(resource)
  end

  # Authenticates the current scope and gets the current resource from the session.
  def authenticate_scope!
    send(:"authenticate_#{resource_name}!",force: true)
    self.resource = send(:"current_#{resource_name}")
  end

  def sign_up_params
    devise_parameter_sanitizer.sanitize(:sign_up)
  end

  def account_update_params
    devise_parameter_sanitizer.sanitize(:account_update)
  end

  def translation_scope
    'devise.registrations'
  end
end

ruby2.3.3
铁轨(4.2.7.1)
设计(4.2.0)