无法读取未定义的属性 'user_first_name'

Question

我正在尝试使用 expressjs/mongoose 注册用户，但出现以下错误：

TypeError: Cannot read property 'user_first_name' of undefined
at C:\Quiz webPolitica\server.js:20:24
at Layer.handle [as handle_request] (C:\Quiz webPolitica\node_modules\express\lib\router\layer.js:95:5)
at next (C:\Quiz webPolitica\node_modules\express\lib\router\route.js:131:13)
at Route.dispatch (C:\Quiz webPolitica\node_modules\express\lib\router\route.js:112:3)
at Layer.handle [as handle_request] (C:\Quiz webPolitica\node_modules\express\lib\router\layer.js:95:5)
at C:\Quiz webPolitica\node_modules\express\lib\router\index.js:277:22
at Function.process_params (C:\Quiz webPolitica\node_modules\express\lib\router\index.js:330:12)
at next (C:\Quiz webPolitica\node_modules\express\lib\router\index.js:271:10)
at serveStatic (C:\Quiz webPolitica\node_modules\express\node_modules\serve-static\index.js:75:16)
at Layer.handle [as handle_request] (C:\Quiz webPolitica\node_modules\express\lib\router\layer.js:95:5)
at trim_prefix (C:\Quiz webPolitica\node_modules\express\lib\router\index.js:312:13)
at C:\Quiz webPolitica\node_modules\express\lib\router\index.js:280:7
at Function.process_params (C:\Quiz webPolitica\node_modules\express\lib\router\index.js:330:12)
at next (C:\Quiz webPolitica\node_modules\express\lib\router\index.js:271:10)
at expressInit (C:\Quiz webPolitica\node_modules\express\lib\middleware\init.js:33:5)
at Layer.handle [as handle_request] (C:\Quiz webPolitica\node_modules\express\lib\router\layer.js:95:5)

我已经尝试调试了几个小时并查找了其他人的问题，但我一无所获。非常感谢任何帮助。请在下面查看我的代码：

server.js

var express = require('express');
var app = express();

app.use(express.static(__dirname + '/public'));

var mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/iPolitico');

var Register_User_Schema = new mongoose.Schema({
    Firstname: { type: String, required: true },
    Lastname:  { type: String, required: true },
    Email:     { type: String, required: true, index: { unique: true } },
    Password:  { type: String, required: true }
}, {collection:"user"});

var Register_User = mongoose.model("Register_User", Register_User_Schema);

app.post('/register', function(req,res){
  new Register_User({
    Firstname: req.body.user_first_name,
    Lastname : req.body.user_last_name,
    Email    : req.body.user_email,
    Password : req.body.user_password
  }).save(function(err, doc){
    if(err){
      res.json;
    }else{
      app.use(express.static(__dirname + '/user_profile.html'));
    }
  })
});

app.get('/', function(req, res){
  //res.send('hello world');
  Register_User.find(function (err, data){
    res.json(data);
  });
});

app.listen(3000);

index.html

<form role="form" action="/register" method="POST" class="registration_form">  <!--action="javascript:;" onsubmit="register_user()"-->
    <div class="form-group">
<label class="sr-only" for="form-first-name">First name</label>
        <input type="text" name="user_first_name"  id="user_first_name" placeholder="First name..." class="form-first-name form-control" >
     </div>
     <div class="form-group">
        <label class="sr-only" for="form-last-name">Last name</label>
        <input type="text" name="user_last_name" id="user_last_name" placeholder="Last name..." class="form-last-name form-control">
     </div>
     <div class="form-group">
        <label class="sr-only" for="form-email">Email</label>
        <input type="text" name="user_email" id="user_email" placeholder="Email..." class="form-email form-control" >
     </div>
     <div class="form-group">
        <label class="sr-only" for="form-password">Senha</label>
        <input type="password" name="user_password" id="user_password" placeholder="Senha..." class="form-password form-control" >
     </div>
     <div class="form-group">
         <label class="sr-only" for="form-password">Confirmar Senha</label>
        <input type="password" name="user_confirm_password" placeholder="Confirmar Senha..." class="form-password form-control" >
    </div>
    <button type="submit">Sign me up!</button>
   </form>

作为附带问题。当我完成注册后，我想重定向到一个新页面。我目前有 "app.use(express.static(__dirname + '/user_profile.html'));"，但我很确定这不正确或一半正确。

Answer 1

你的错误只是说 req.body 中的正文是空的。所以在谷歌搜索 Stack Overflow returned me to this question 之后。基本上它说：

You must use something to parse the request's body data.

这意味着使用 bodyParser

但是正如@andrea.spot 在评论中提到的那样，自从 Express4（我假设您正在使用）以来，必须单独安装 BodyParser 中间件。

因此对于 Express4，@Jay 的回答建议您在配置 express 时应使用以下内容：

var bodyParser = require('bodyParser');
app.use(bodyParser().json());`

此外，正如@Jay 指出的那样，您可以通过调用以下方式安装它：

npm install body-parser --save

Answer 2

req.body 实际上由 Express 中的中间件处理，在您的自定义代码访问它之前将请求数据转换为 JSON。

尝试在您的项目 (npm install body-parser) 中包含 body-parser 并在您的第一个 app.post:

之前添加它

var bodyParser = require('body-parser');
app.use(bodyParser.json());

这将获取对您服务器的请求，从您的 POST 调用中解析出数据，并将其作为 req.body.

放入 JSON 对象中

至于重定向，在调用结束时添加一个简单的 res.redirect('/newPage')

无法读取未定义的 属性 'user_first_name'

Cannot read property 'user_first_name' of undefined

javascript

user-registration

mongoose

mongodb

express

无法读取未定义的属性 'user_first_name'