[英]Error in node.js/express app: Can't set headers after they are sent
我在通过Express设置Node.js应用程序以进行路由而在数据库中使用MongoDB(Mongolab)时遇到了问题。 我一直在环顾四周,发现许多其他用户都遇到相同的问题,但仍未找到解决问题的方法。希望有人能提供帮助。
我一直收到的Error: Can't set headers after they are sent.
是Error: Can't set headers after they are sent.
POST /login
请求后出现错误。 我试图使用res.end();
, res.redirect('/users/index');
并返回渲染。.但是还没有成功..
这里最重要的代码:
Server.js
/* LOAD ALL DEPENDENCIES
----------------------------------------- */
const express = require('express');
const path = require('path');
const request = require('request');
const session = require('express-session');
const compression = require('compression');
const bodyParser = require('body-parser');
const app = express();
/* MONGODB CONFIGURATION
----------------------------------------- */
const MongoClient = require("mongodb").MongoClient;
require('dotenv').config();
const dbConfig = process.env.MONGODB_URI;
MongoClient.connect(dbConfig, (err, database) => {
if (err) return console.log(err)
db = database
});
/* SESSIONS CONFIGURATION
----------------------------------------- */
app.use(session({
secret: "JA1d82JHYF9?nsdfDF635MuHe#ksd",
resave: false,
saveUninitialized: true
}));
/* SET PORT FOR HEROKU
----------------------------------------- */
const port = process.env.PORT || 3000;
const host = process.env.HOST ||'0.0.0.0';
// Rest of the code ..
app.use('/users', usersRouter);
// Router is loaded earlier
/* START THE NPM SERVER
----------------------------------------- */
app.listen(port, host, function() {
console.log(`Server started on port ${port}`);
});
users.js(路由)
/* LOAD ALL DEPENDENCIES
----------------------------------------- */
const express = require('express');
const router = express.Router();
const passwordHash = require('password-hash');
/* INDEX ROUTE
----------------------------------------- */
router.get('/', function(req, res) {
if (req.session.login) {
res.render('users/index');
} else {
res.redirect('/users/login');
}
});
router.get('/login', function(req, res) {
res.render('users/login');
});
router.post('/login', function(req, res) {
const loginName = req.body.username;
const loginPassword = req.body.password;
db.collection('users').find().toArray(function(err, results) {
results.map(function(user) {
if (user['username'] === loginName) {
const pwCheck = passwordHash.verify(loginPassword, user['password']);
if(pwCheck === true) {
req.session.login = true;
req.session.username = user['username'];
res.render('users/index');
} else {
res.redirect('/users/')
}
}
})
});
});
完全错误
Error: Can't set headers after they are sent.
at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:356:11)
at ServerResponse.header (/Users/camillesebastien/Documents/Programming/Mongo App/node_modules/express/lib/response.js:725:10)
at ServerResponse.send (/Users/camillesebastien/Documents/Programming/Mongo App/node_modules/express/lib/response.js:170:12)
at done (/Users/camillesebastien/Documents/Programming/Mongo App/node_modules/express/lib/response.js:962:10)
at tryHandleCache (/Users/camillesebastien/Documents/Programming/Mongo App/node_modules/ejs/lib/ejs.js:208:10)
at View.exports.renderFile [as engine] (/Users/camillesebastien/Documents/Programming/Mongo App/node_modules/ejs/lib/ejs.js:412:10)
at View.render (/Users/camillesebastien/Documents/Programming/Mongo App/node_modules/express/lib/view.js:128:8)
at tryRender (/Users/camillesebastien/Documents/Programming/Mongo App/node_modules/express/lib/application.js:640:10)
at EventEmitter.render (/Users/camillesebastien/Documents/Programming/Mongo App/node_modules/express/lib/application.js:592:3)
at ServerResponse.render (/Users/camillesebastien/Documents/Programming/Mongo App/node_modules/express/lib/response.js:966:7)
我的问题
该错误的确切含义是什么,出了什么问题? 在这种情况下,我该如何解决?
我在Node.JS中构建,其中Express作为路由器,而mongoDB作为数据库。 可能与这有关吗?
我在Stackoverflow上检查了很多类似的问题,但是还不能解决我的问题。
希望有人能帮助我,在此先感谢!
刚想到:
问题可能是我在localhost上测试,而mongodb(mongolab)在Heroku上设置了吗?
您的问题是,对于数据库查询返回的每个与密码和用户名匹配的结果值,您都在调用res.render()
。 每个请求只能调用res.render()
。 因此,从理论上讲,如果仅返回1个用户并且其密码匹配,这将起作用,但是如果同一用户多次存在并且具有相同的密码,则在发送一次之后将调用res.render()
。
我的建议是遍历返回的用户列表,然后在首次匹配后细分。
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