nil:NilClass 的未定义方法 ID

Question

我在 RoR 中遇到了这个错误：

于 2017 年 11 月 10 日 15:03:09 -0200 开始为 127.0.0.1 发布 POST "/conversations?person_id=3" ConversationsController#create as JS 处理 参数：{"person_id"=>"3"} 1ms 内完成 500 Internal Server Error (ActiveRecord: 0.0ms)

NoMethodError（nil:NilClass 的未定义方法 `id'）：

app/controllers/conversations_controller.rb:3:in `create'

我的对话控制器：

class ConversationsController < ApplicationController
 def create
 @conversation = Conversation.get(current_person.id, params[:person_id])

 add_to_conversations unless conversated?

 respond_to do |format|
   format.js
 end
end

def close
  @conversation = Conversation.find(params[:id])

  session[:conversations].delete(@conversation.id)

  respond_to do |format|
    format.js
  end
end

private

def add_to_conversations
  session[:conversations] ||= []
  session[:conversations] << @conversation.id
end

def conversated?
  session[:conversations].include?(@conversation.id)
end
end

对话模型：

class Conversation < ApplicationRecord
  has_many :messages, dependent: :destroy
  belongs_to :sender, foreign_key: :sender_id, class_name: Person
  belongs_to :recipient, foreign_key: :recipient_id, class_name: Person

  validates :sender_id, uniqueness: { scope: :recipient_id }

  scope :between, -> (sender_id, recipient_id) do
  where(sender_id: sender_id, recipient_id: recipient_id).or(
    where(sender_id: recipient_id, recipient_id: sender_id)
  )
end

def self.get(sender_id, recipient_id)
  conversation = between(sender_id, recipient_id).first
  return conversation if conversation.present?

  create(sender_id: sender_id, recipient_id: recipient_id)
end

def opposed_person(person)
  person == recipient ? sender : recipient
end
end

会话创建.js

var conversations = $('#conversations-list');
var conversation = conversations.find("[data-conversation-id='" + "<%=     @conversation.id %>" + "']");

if (conversation.length !== 1) {
   conversations.append("<%= j(render 'conversations/conversation',    conversation: @conversation, person: current_person) %>");
   conversation = conversations.find("[data-conversation-id='" + "<%=      @conversation.id %>" + "']");
 }

conversation.find('.panel-body').show();

var messages_list = conversation.find('.messages-list');
var height = messages_list[0].scrollHeight;
messages_list.scrollTop(height);

Answer 1

以下似乎返回 nil

 @conversation = Conversation.get(current_person.id, params[:person_id])

如果您无法使用断点进行调试，您可以这样做：

puts "#{current_person.id} | #{params[:person_id]} | #{@conversation.to_sql}" 

看看发生了什么。

我想 current_person 是在其他地方设置的，就像设计中的 current_user 一样。