NodeJS错误 – 发送后无法设置标题

我在NodeJS方面比较新，我正在学习这个系列教程。

https://www.youtube.com/watch?v=49sWXJPk10Q&list=PLO-hrPk0zuI18xlF_480s6UiaGD7hBqJa&index=15

在这个特定的video中，我提交表单后出现一些错误。 我有两个怀疑，在这个网站search没有得到明确的答案。 我希望你能给我更多的清晰。

1.在users.js中，在第32行中，它说未定义的profileimage，事实上我有一个名为profileimage的文件域。

2.如果该行被改为req.body.profileimage，那不会产生错误，但我认为它仍然是错误的。 提交表单时，nodeJS会抛出错误

错误“发送后无法设置标题”

我尝试阅读其他类似的问题，但我不能把它与我的程序（因为我没有明确地在我的程序中设置任何标题）。 请更深入了解这两个问题。

var express = require('express'); var router = express.Router(); //var User = require('../models/user'); /* GET users listing. */ router.get('/', function(req, res, next) { res.send('respond with a resource'); }); router.get('/register', function(req, res, next) { res.render('register', { 'title': "Register" }); }); router.get('/login', function(req, res, next) { res.render('login', { 'title': "Login" }); }); router.post('/register', function(req, res, next) { //Get form values var name = req.body.name; var email = req.body.email; var password = req.body.password; var cpassword = req.body.cpassword; //Check for image field if(req.files.profileimage) { console.log('Uploading File...'); //File Info var profileImageOriginalName = req.files.profileimage.originalname; var profileImageName = req.files.profileimage.name; var profileImageMime = req.files.profileimage.mimetype; var profileImagePath = req.files.profileimage.path; var profileImageExt = req.files.profileimage.extension; var profileImageSize = req.files.profileimage.size; } else { var profileImageName = 'default.png'; } //form validation req.checkBody('name','Name field is required').notEmpty(); req.checkBody('email','Email field is required').notEmpty(); req.checkBody('email','Enter a valid Email').isEmail(); req.checkBody('password','Password field is required').notEmpty(); req.checkBody('cpassword','Passwords fields do not match').equals(req.body.password); var errors = req.validationErrors(); if(errors) { res.render('register', { errors: errors, name: name, email: email, password: password }); } else { var newUser = new User({ name: name, email: email, password: password, profileImage: profileImageName }); } */ //Success Message req.flash('success','You are now registered and may log in'); res.location('/'); res.redirect('/'); }); module.exports = router; 

register.jade

 extends layout block content ul.errors if errors each error, i in errors li.alert.alert-danger #{error.msg} form.form-signin(method='post',action='/users/register',enctype='multipart/form-data') h2.form-signin-heading.text-center Register label.sr-only(for='inputName') Name input#inputName.form-control(name='name' type='text', placeholder='Name', autofocus='') label.sr-only(for='inputEmail') Email address input#inputEmail.form-control(name='email' type='email', placeholder='Email address') label.sr-only(for='inputPassword') Password input#inputPassword.form-control(name='password' type='password', placeholder='Password') label.sr-only(for='inputCPassword') Confirm Password input#inputCPassword.form-control(name='cpassword' type='password', placeholder='Confirm Password') label.sr-only(for='inputProfile') Profile Image input#inputProfile.form-control(name='profileimage' type='file') button.btn.btn-lg.btn-primary.btn-block(type='submit') Register 

更详细的错误报告

 POST /users/register 500 91.651 ms - 2704<br> Error: Can't set headers after they are sent. at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:335:11) at ServerResponse.header (C:\Dev\nodeauth\node_modules\express\lib\response. js:718:10) at ServerResponse.send (C:\Dev\nodeauth\node_modules\express\lib\response.js :163:12) at done (C:\Dev\nodeauth\node_modules\express\lib\response.js:957:10) at Object.exports.renderFile (C:\Dev\nodeauth\node_modules\jade\lib\index.js :374:12) at View.exports.__express [as engine] (C:\Dev\nodeauth\node_modules\jade\lib \index.js:417:11) at View.render (C:\Dev\nodeauth\node_modules\express\lib\view.js:126:8) at tryRender (C:\Dev\nodeauth\node_modules\express\lib\application.js:639:10 ) at EventEmitter.render (C:\Dev\nodeauth\node_modules\express\lib\application .js:591:3) at ServerResponse.render (C:\Dev\nodeauth\node_modules\express\lib\response. js:961:7) at C:\Dev\nodeauth\app.js:104:7 at Layer.handle_error (C:\Dev\nodeauth\node_modules\express\lib\router\layer .js:71:5) at trim_prefix (C:\Dev\nodeauth\node_modules\express\lib\router\index.js:310 :13) at C:\Dev\nodeauth\node_modules\express\lib\router\index.js:280:7 at Function.process_params (C:\Dev\nodeauth\node_modules\express\lib\router\ index.js:330:12) at IncomingMessage.next (C:\Dev\nodeauth\node_modules\express\lib\router\ind ex.js:271:10) at done (C:\Dev\nodeauth\node_modules\express\lib\response.js:956:25) at tryRender (C:\Dev\nodeauth\node_modules\express\lib\application.js:641:5) at EventEmitter.render (C:\Dev\nodeauth\node_modules\express\lib\application .js:591:3) at ServerResponse.render (C:\Dev\nodeauth\node_modules\express\lib\response. js:961:7) at C:\Dev\nodeauth\app.js:93:9 at Layer.handle_error (C:\Dev\nodeauth\node_modules\express\lib\router\layer .js:71:5) 

Answer 1

你需要移动这个代码：

 //Success Message req.flash('success','You are now registered and may log in'); res.location('/'); res.redirect('/'); 

它应该在条件的内部：

 else { var newUser = new User({ name: name, email: email, password: password, profileImage: profileImageName }); //Success Message req.flash('success','You are now registered and may log in'); res.location('/'); res.redirect('/'); } 

如果你在外面发生了什么事情，你会得到一个错误是这样的。 首先你的if语句触发：

 if(errors) { res.render('register', { errors: errors, name: name, email: email, password: password }); } 

当res.render被调用时，响应被完成并且头部被发送。 但是：因为你有res.redirect和res.location以外的条件Express也试图运行这个。 这就是为什么你会收到错误信息。

另外正如你对你的问题的评论中指出的，你可以在这里阅读更多。