[英]Error in node.js/express app: Can't set headers after they are sent
我在通過Express設置Node.js應用程序以進行路由而在數據庫中使用MongoDB(Mongolab)時遇到了問題。 我一直在環顧四周,發現許多其他用戶都遇到相同的問題,但仍未找到解決問題的方法。希望有人能提供幫助。
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
請求后出現錯誤。 我試圖使用res.end();
, res.redirect('/users/index');
並返回渲染。.但是還沒有成功..
這里最重要的代碼:
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/')
}
}
})
});
});
完全錯誤
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)
我的問題
該錯誤的確切含義是什么,出了什么問題? 在這種情況下,我該如何解決?
我在Node.JS中構建,其中Express作為路由器,而mongoDB作為數據庫。 可能與這有關嗎?
我在Stackoverflow上檢查了很多類似的問題,但是還不能解決我的問題。
希望有人能幫助我,在此先感謝!
剛想到:
問題可能是我在localhost上測試,而mongodb(mongolab)在Heroku上設置了嗎?
您的問題是,對於數據庫查詢返回的每個與密碼和用戶名匹配的結果值,您都在調用res.render()
。 每個請求只能調用res.render()
。 因此,從理論上講,如果僅返回1個用戶並且其密碼匹配,這將起作用,但是如果同一用戶多次存在並且具有相同的密碼,則在發送一次之后將調用res.render()
。
我的建議是遍歷返回的用戶列表,然后在首次匹配后細分。
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