Rails 7 - CurrentAttributes undefined

Question

有人能解释一下为什么吗：

 after_commit :send_partial_

 def send_partial_
  
   broadcast_update_to( ... locals:users_in_room_list )

 end
 

 def users_in_room_list

  user = User.find_by(id:Current.user.id)  // return undefined method `id' for 
  nil:NilClass

  user_name =  User.find_by(Current.user) // return <User:0x00007fbecc0dcf40>

 end

为什么我得到

undefined method 'id' for nil:NilClass

的

user

但我得到正确的数据

user_name

??

Answer 1

你的Current.user是nil（意思是没有内容）

如果你问 user_name = User.find_by(Current.user) 这个语句导致一个用户你可以试试这个代码

  x = nil
  user_name = User.find_by(x)
  # this will run query as follow
  SELECT "users".* FROM "users" LIMIT $1  [["LIMIT", 1]]

编辑2：

根据您之前的问题您的源代码

  class ApplicationController < ActionController::Base

    before_action :set_current_user, if: :user_signed_in?

    private 
    
    def set_current_user
        Current.user = current_user
      # this variable current_user is nil
      # that's why your Current.user = nil
    end

  end