遇到Pundit我不理解的事情,
使用Rails 4.2.5.1,Pundit 1.1.0和Devise进行身份验证 .
我正在尝试使用BlogController #Index操作的策略范围 .
-
如果用户是管理员,则显示所有帖子(草稿,已发布)
-
如果用户是标准用户,则仅显示标记为已发布的帖子
-
如果没有用户/用户未登录,则显示仅标记为已发布的帖子
得到错误:
未定义的方法`admin?'为零:NilClass
Live shell揭示:
>> user
=> nil
# ApplicationController
class ApplicationController < ActionController::Base
include Pundit
rescue_from Pundit::NotAuthorizedError, with: :user_not_authorized
# Prevent CSRF attacks by raising an exception.
# For APIs, you may want to use :null_session instead.
protect_from_forgery with: :exception
private
def user_not_authorized
flash[:error] = "You are not authorized to perform this action."
redirect_to(request.referrer || root_path)
end
end
# BlogController
# == Schema Information
#
# Table name: blogs
#
# id :integer not null, primary key
# title :string default(""), not null
# body :text default(""), not null
# published :boolean default("false"), not null
# created_at :datetime not null
# updated_at :datetime not null
#
class BlogsController < ApplicationController
before_action :set_blog, only: [:show, :edit, :update, :destroy]
before_action :authenticate_user!, except: [:index, :show]
after_action :verify_authorized, except: [:index, :show]
after_action :verify_policy_scoped, only: [:index]
def index
@blogs = policy_scope(Blog)
authorize @blog
end
def show
end
def new
@blog = Blog.new
authorize @blog
end
def edit
authorize @blog
end
def create
@blog = Blog.new(blog_params)
@blog.user = current_user if user_signed_in?
authorize @blog
if @blog.save
redirect_to @blog, notice: "Blog post created."
else
render :new
end
end
def update
authorize @blog
if @blog.update(blog_params)
redirect_to @blog, notice: "Blog updated."
else
render :edit
end
end
def destroy
authorize @blog
@blog.destroy
redirect_to blogs_url, notice: "Blog post deleted."
end
private
def set_blog
@blog = Blog.friendly.find(params[:id])
end
def blog_params
params.require(:blog).permit(*policy(@blog|| Blog).permitted_attributes)
end
end
# Application Policy
class ApplicationPolicy
attr_reader :user, :record
def initialize(user, record)
@user = user
@record = record
end
def index?
false
end
def show?
scope.where(:id => record.id).exists?
end
def create?
false
end
def new?
create?
end
def update?
false
end
def edit?
update?
end
def destroy?
false
end
def scope
Pundit.policy_scope!(user, record.class)
end
class Scope
attr_reader :user, :scope
def initialize(user, scope)
@user = user
@scope = scope
end
def resolve
scope
end
end
end
# Blog Policy
class BlogPolicy < ApplicationPolicy
class Scope < Scope
def resolve
if user.admin?
scope.all
else
scope.where(published: true)
end
end
end
def new?
user.admin?
end
def index?
true
end
def update?
user.admin?
end
def create?
user.admin?
end
def destroy?
user.admin?
end
def permitted_attributes
if user.admin?
[:title, :body]
end
end
end
在我创建的Pundit BlogPolicy范围中:
class Scope < Scope
def resolve
if user.admin?
scope.order('id DESC')
else
scope.where('published: true')
end
end
end
如果我以管理员用户身份登录,则可以正常工作 .
我可以查看所有博客帖子 .
如果我以标准用户身份登录,则可以使用 .
标准用户会看到标记为已发布的博文 .
如果我没有登录用户为零,我收到错误:
NoMethodError at /blog
undefined method `admin?' for nil:NilClass
我可以在 user.admin?
之前添加另一个子句 elsif user.nil?
或 case when
语句,但我认为如果用户不是管理员,它应该只显示else块中的内容?
# This seems wrong?
class Scope < Scope
def resolve
if user.nil?
scope.where('published: true')
elsif user.admin?
scope.all
else
scope.where('published: true')
end
end
end
任何指针都非常赞赏
2 回答
你可以用try:
http://api.rubyonrails.org/v4.2.5/classes/Object.html#method-i-try
发生这种情况是因为当您没有登录时没有用户 . (可能是
user
变量nil
值被分配到某处,所以您试图在nil
对象上调用admin?
方法)如果您使用ruby 2.3.0或更新版本,最好使用safe navigation
如果您使用其他ruby版本