Rails的未定義的方法'用戶」的零：NilClass

Question

大家好我是新來導軌出於某種原因，我不斷收到一個錯誤

undefined method 'user' for nil:NilClass。

我在底部粘貼了一個錯誤圖像，我發佈了下面的代碼。

Image Error

# registeredapps_controller.rb

class RegisteredappsController < ApplicationController 

def create 
    @registeredapp = Registeredapp.new(registeredapp_params) 
    @registeredapp.user = current_user 

    unless RegisteredappPolicy.new(current_user, @registeredapp).create? 
    flash[:alert] = "not authorized" 
    redirect_to user_registeredapps_path(current_user.id) 
    end 

    if @registeredapp.save 
    flash[:notice] = "You successfully registered your app." 
    redirect_to user_registeredapp_path(current_user.id, @registeredapp.id) 
    else 
    flash.now[:alert] = "There was an error registering your app. Please try again." 
    render :new 
    end 
end 

策略（使用權威人士GEM）
# registeredapp_policy.rb

class RegisteredappPolicy 

    def initialize(user, registeredapp) 
    @registeredapp = registeredapp 
    @user = user 
    end 

    def create? 
    if @user.present? 
    @user = @registerdapp.user 
    else 
    false 
    end 
end 

這裏是我的模型

# models/user.rb

class User < ApplicationRecord 

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

    def avatar_url(size) 
    gravatar_id = Digest::MD5::hexdigest(self.email).downcase 
    "http://gravatar.com/avatar/#{gravatar_id}.png?s=#{size}" 
    end 

    has_many :registeredapps 
end 

# models/registeredapp.rb

Answer 1

你的問題是，實例變量@registeredapp在RegisteredappPolicy類下create?法拼寫錯誤。

它目前是

def create? 
    if @user.present? 
    @user = @registerdapp.user 
    else 
    false 
    end 
end 

而在初始化中定義的變量是@registeredapp你錯過了一個e

Answer 2

@registerdapp是nil

@user = @registerdapp.user 

使用try

@user = @registerdapp.try(:user) 

或

def create? 
    if @user.present? && @registerdapp.present? 
    @user = @registerdapp.user 
    else 
    false 
    end 
end 

注：你也缺少了if else一個end在create?方法

Answer 3

Rails約定通常是有這樣的型號名稱：

User 

及其對應表名如：

users 

在你的ActiveRecord :: Registeredapp中你有:user，請檢查你是否不應該有:users。