Javascript TypeError:无法读取未定义的属性“id”（用户未定义）

我正在制作一个ReactJs应用程序，它是从CreateRepackApp-full开始的，它为我设置了很多东西，包括使用Desive gem的用户，并且不需要一路设置标题。我创建了一个具有典型test@test.com，等等。但当我尝试加载我的主页时，标题中出现了错误。我试图让我的主页有条件地呈现，这取决于用户是否登录

以下是组件：

import React, { Component } from 'react';
import { Header } from 'semantic-ui-react';

class Home extends Component {

  homePage = () => {
    debugger 
    const { user } = this.props;
    if (user.id) {
      return (
        <div>
          <div>Games</div>
          <div>Sessions</div> 
          <div>Friends</div>
          <div>Tools</div> 
          <div>Help</div>
          <div>Settings</div>
          <div>Profile</div>
        </div>
      );
    }
    return (
      <div>
        <Header as='h1' textAlign='center'>Welcome to Board Game Tracker</Header>
        <Header as='h2' textAlign='center'>Please Log In or Register</Header>
      </div>
    );
  }

  render() {
    return (
      <div>
        { this.homePage() }
      </div>
    );
  }
}

const mapStateToProps = state => {
  return { user: state.user };
};

export default Home;

我已经有一段时间没有从头开始开发新的应用程序了，我可能错过了一些非常基本的东西

以下是完整的错误：

×
TypeError: Cannot read property 'id' of undefined
Home._this.homePage
src/components/Home.js:9
   6 | homePage = () => {
   7 |   debugger 
   8 |   const { user } = this.props;
>  9 |   if (user.id) {
  10 |     return (
  11 |       <div>
  12 |         <div>Games</div>
View compiled
Home.render
src/components/Home.js:33
  30 | render() {
  31 |   return (
  32 |     <div>
> 33 |       { this.homePage() }
  34 |     </div>
  35 |   );
  36 | } 

最后是终端错误：

Started GET "/api/auth/validate_token" for 127.0.0.1 at 2018-10-18 09:22:43 -0600
Processing by DeviseTokenAuth::TokenValidationsController#validate_token as HTML
/Users/michellegarcia/personal_projects/board_game_app/app/controllers/application_controller.rb:6: warning: already initialized constant ApplicationController::NameError
/Users/michellegarcia/personal_projects/board_game_app/app/controllers/application_controller.rb:6: warning: previous definition of NameError was here
uninitialized constant ApplicationController::Api
  User Load (3.7ms)  SELECT  "users".* FROM "users" WHERE "users"."uid" = $1 LIMIT $2  [["uid", "test@test.com"], ["LIMIT", 1]]
  ↳ /Users/michellegarcia/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activerecord-5.2.1/lib/active_record/log_subscriber.rb:98
   (0.3ms)  BEGIN
  ↳ /Users/michellegarcia/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activerecord-5.2.1/lib/active_record/log_subscriber.rb:98
  User Load (1.3ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = $1 LIMIT $2 FOR UPDATE  [["id", 1], ["LIMIT", 1]]
  ↳ /Users/michellegarcia/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activerecord-5.2.1/lib/active_record/log_subscriber.rb:98
  User Update (1.5ms)  UPDATE "users" SET "tokens" = $1, "updated_at" = $2 WHERE "users"."id" = $3  [["tokens", "{\"8ruFDYLiKIRAhTy1Cc0tnw\":{\"token\":\"$2a$10$3UtLDmi5ljtUJOfKwzx.y.njRRkZiFNoyYOBi35FGL6RxkHcsBHye\",\"expiry\":1541085763,\"last_token\":\"$2a$10$OiJjztMk7.bYuWxgwHKYmewx8T5xO00IM6iaLxQ/pMAsSdNwagy9W\",\"updated_at\":\"2018-10-18T09:22:43.556-06:00\"}}"], ["updated_at", "2018-10-18 15:22:43.659159"], ["id", 1]]
  ↳ /Users/michellegarcia/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activerecord-5.2.1/lib/active_record/log_subscriber.rb:98
   (8.3ms)  COMMIT
  ↳ /Users/michellegarcia/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activerecord-5.2.1/lib/active_record/log_subscriber.rb:98
Completed 200 OK in 289ms (Views: 1.6ms | ActiveRecord: 15.1ms)


Started GET "/%3Canonymous%3E" for 127.0.0.1 at 2018-10-18 09:22:46 -0600
Processing by StaticController#index as */*
  Parameters: {"other"=>"<anonymous>"}
Completed 500 Internal Server Error in 186ms (ActiveRecord: 0.0ms)



ActionView::MissingTemplate (Missing template Users/michellegarcia/personal_projects/board_game_app/public/index.html with {:locale=>[:en], :formats=>[:html, :text, :js, :css, :ics, :csv, :vcf, :vtt, :png, :jpeg, :gif, :bmp, :tiff, :svg, :mpeg, :mp3, :ogg, :m4a, :webm, :mp4, :otf, :ttf, :woff, :woff2, :xml, :rss, :atom, :yaml, :multipart_form, :url_encoded_form, :json, :pdf, :zip, :gzip], :variants=>[], :handlers=>[:raw, :erb, :html, :builder, :ruby]}. Searched in:
  * "/Users/michellegarcia/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/railties-5.2.1/lib/rails/templates"
  * "/Users/michellegarcia/personal_projects/board_game_app"
  * "/"
):

app/controllers/static_controller.rb:7:in `index'

Postgres肯定是开着的，我肯定有一个用户

---

提前谢谢

看起来您可能需要将主组件连接到redux应用商店

import { connect } from 'react-redux';

export default connect(mapStateToProps)(Home);

---

当您使用console.logthis.props时会发生什么？代码看起来很好。您得到的错误是由于试图访问未定义对象的属性而导致的，在您的案例中是用户对象。尝试从数据库检索用户时可能会发生错误。这可能有几个不同的原因，例如没有等待您的响应、身份验证或数据不存在。@joshbang This.props可以工作，但我在其中找不到用户。此.State为null。已修复它。你是上帝，很高兴我能帮上忙。