Ruby :无方法error..Undefined方法invitation_type用于nil:NilClass

Question

我正在做Railssite.我在重定向到另一种形式时遇到了问题.我做了很多事情来修复它，但是我无法找出code..anyone中有什么问题，请帮助我修复它，..please

误差

←[36m2014-04-23T05:46:13.280376+00:00 app[web.1]:←[0m NoMethodError (undefined m
ethod `invitation_type' for nil:NilClass):
←[36m2014-04-23T05:46:13.280378+00:00 app[web.1]:←[0m   app/controllers/vectors_controller.rb in invited_new

代码：

    class VectorsController < ApplicationController

    def create
        ui = UserInvitation.where(hash_code: session[:hash_code]).first
        @vector = Vector.new(vector_params.merge({user_id: current_user.id, vector_type: ui.invitation_type}))

    respond_to do |format|
      if @vector.save

        ui.completed_registration = true
        ui.save

        session[:hash_code] = nil
        flash[:notice] = "You're all set! Welcome to Availendar!"

        format.html {redirect_to vector_path(@vector.id)}
      else
        flash[:alert] = "Oops, looks like there's been a problem. Please correct it and try again."

        format.html {render action: :invited_new}
      end
    end
  end


  def invited_new
    @user_invitation = UserInvitation.where(hash_code: session[:hash_code]).first
    #raise ArgumentError "Cannot find invitation with hash_code #{session[:hash_code]}" unless @user_invitation.present?

    @vector = Vector.new(user: current_user, vector_type: @user_invitation.invitation_type)
    @vector.build_address
  end
 ////create action///

def创建ui = UserInvitation.where(hash_code: session:hash_code).first @vector =Vector.new({user_id: current_user.id，( vendor_type: ui.invitation_type})如果@vector.save ui.completed_registration = true ui.save session:hash_code = nil format.html {redirect_to vector_path(@vector.id)} @vector.save format.html {呈现操作：:invited_new} end end )

Answer 1

在您的invited_new操作中，@user_invitation变为空白，因为它显示了此错误，下面是解决方案

  def invited_new
    @user_invitation = UserInvitation.where(hash_code: session[:hash_code]).first

    unless @user_invitation.blank?    
      @vector = Vector.new(user: current_user, vector_type: @user_invitation.invitation_type)
      @vector.build_address
    end
  end

Answer 2

您将unless用于if，错误也是如此。

更改这一行

unless @user_invitation.present? #=> false

至

if @user_invitation.present? #=> true



def invited_new
    @user_invitation = UserInvitation.where(hash_code: session[:hash_code]).first

    if @user_invitation.present?

    @vector = Vector.new(user: current_user, vector_type: @user_invitation.invitation_type)
    @vector.build_address
  end

Answer 3

好的，让我们试着一步一步地分解它：

问题

• 有时，这一行可能返回空白数组(一无所获)。

UserInvitation.where(hash_code: session:hash_code)

• 这意味着，这将是nil (第一个空白数组为零，对!)

@user_invitation = UserInvitation.where(hash_code: session:hash_code).first

• 现在，这是有意义的抛出(未定义的方法invitation_type为nil:NilClass)

@user_invitation.invitation_type

溶液

相反，使用试一试，如名称所示，它将尝试获取属性，或者在调用nil对象时只返回nil，因此您的方法应该如下所示：

class VectorsController < ApplicationController

  def create
    ui = UserInvitation.where(hash_code: session[:hash_code]).first
    @vector = Vector.new(vector_params.merge({user_id: current_user.id, vector_type: ui.try(:invitation_type)}))

    respond_to do |format|
      if @vector.save
        ui.completed_registration = true
        ui.save
        session[:hash_code] = nil
        flash[:notice] = "You're all set! Welcome to Availendar!"
        format.html {redirect_to vector_path(@vector.id)}
      else
        flash[:alert] = "Oops, looks like there's been a problem. Please correct it and try again."
        format.html {render action: :invited_new}
      end
    end
  end

  def invited_new
    @user_invitation = UserInvitation.where(hash_code: session[:hash_code]).first
    #raise ArgumentError "Cannot find invitation with hash_code #{session[:hash_code]}" unless @user_invitation.present?

    @vector = Vector.new(user: current_user, vector_type: @user_invitation.try(:invitation_type))
    @vector.build_address
  end
end