我在NodeJS方面相对较新，我从本教程系列中学习。
https://www.youtube.com/watch?v=49sWXJPk10Q&list=PLO-hrPk0zuI18xlF_480s6UiaGD7hBqJa&index=15
在此特定视频中，我在提交表单后遇到了一些错误。我有两个疑问，在这个网站搜索没有得到一个明确的答案。我希望你能给我更多的清晰度。
1.在users.js中，在第32行中它表示未定义的profileimage，尽管我有一个名为profileimage的文件字段。
2.如果该行改为req.body.profileimage，那不会产生错误，但我认为这仍然是错误的。提交表单时，nodeJS抛出错误
错误＆＃39;在发送标题后无法设置标题＆＃39;
我尝试阅读其他类似的问题，但我无法将其与我的程序相关联（因为我没有明确地在程序中设置任何标题）。请更深入地了解这两个问题。
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)
答案 0 :(得分：2)
您需要移动此代码：
//Success Message
req.flash('success','You are now registered and may log in');
res.location('/');
res.redirect('/');
它应该在条件内：
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会发生错误就是这个。首先你的if语句触发：
if(errors) {
res.render('register', {
errors: errors,
name: name,
email: email,
password: password
});
}
调用res.render时，响应完成并发送标头。但是：由于条件Express之外的res.redirect和res.location尝试运行它。这就是您收到错误消息的原因。
正如您对问题的评论中指出的那样，您可以阅读更多here。