node.js res.json 发送后无法设置标头
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/26307920/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
res.json Can't set headers after they are sent
提问by Gatsbill
I'm learning node Js and i'm trying to do a simple subscribe/log_in app. I'm having issue with res.json not working as intended.
我正在学习 node Js，我正在尝试做一个简单的 subscribe/log_in 应用程序。我遇到了 res.json 无法按预期工作的问题。
Got this error when i'm trying to subscribe : Can't set headers after they are sent
当我尝试订阅时出现此错误：发送后无法设置标头
This is my server side script :
这是我的服务器端脚本：
var express = require('express');
var swig = require('swig');
var ent = require('ent');
var bodyParser = require('body-parser');
var mongoose = require('mongoose');
var session = require('express-session');
var app = express();
// Environnement
app.set('port', process.env.PORT || 3000);
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));
app.use("/public", express.static(__dirname + "/public"));
app.engine('html', swig.renderFile);
app.set('view engine', 'html');
app.set('views', __dirname + '/views');
app.set('view cache', false);
swig.setDefaults({ cache: false });
app.use(session({
secret: 'poussixthetruefighteroftheparadise',
saveUninitialized: true,
resave: true
}));
//MongoDB
var db = mongoose.connect('mongodb://127.0.0.1:27017/maBase');
var userSchema = new mongoose.Schema({
login: String,
mail: String,
password: String
});
var user = db.model('user', userSchema)
// variables globales
var state;
// Page Principale
app.get('/', function(req,res){
if (req.session.user) {
res.render('accueil.html',{});
} else {
res.redirect('/connection');
}
});
// Page connection
app.route('/connection')
.get(function(req, res) {
res.render('index.html',{});
if (req.session.state) {
res.json({state: req.session.state});
}
})
.post(function(req, res) {
user.find({login: req.body.login, password: req.body.password}).limit(1).exec(function (err, users) {
if (err) { console.log(err) };
if (!users.length) {
console.log('connection pas ok');
res.json({state: '5'});
}
else {
console.log('connection ok');
res.redirect('/');
}
});
});
// Ajouter Utilisateur
app.post('/connection/ajouter', function(req,res){
var login = req.body.login;
var mail = req.body.mail;
user.find({$or: [{login: login}, {mail: mail}]}).limit(1).exec(function (err, users) {
if (err) { console.log(err) };
if (!users.length) {
console.log('login et mail ok');
if (req.body.password == req.body.password2) {
if (req.body.password.length > 6) {
var values = new user({
login: ent.encode(req.body.login),
mail: ent.encode(req.body.mail),
password: ent.encode(req.body.password)
});
values.save(function(err, values) {
if (err) return console.error(err);
console.log('utilisateur enregistré');
req.session.state = '6';
res.redirect('/connection');
});
} else {
console.log('Mot de passe trop court');
req.session.state = '3';
res.redirect('/connection');
}
} else {
console.log('mot de passe différent');
req.session.state = '4';
res.redirect('/connection');
}
}
else {
console.log('login ou mail déja utilisé');
if (users[0].mail == mail) {
console.log('mail déja utilisé');
req.session.state = '2';
res.redirect('/connection');
} else {
console.log('login déja utilisé');
req.session.state = '1';
res.redirect('/connection');
}
console.log(users);
}
});
});
app.listen(app.get('port'), function(){
console.log('Express server listening on port ' + app.get('port'));
});
And my client side script :
我的客户端脚本：
<html>
<head>
<title>test</title>
<link rel="stylesheet" href="public/css/reset.css">
<link rel="stylesheet" href="public/css/connection.css">
</head>
<body>
<div id="content">
<a href="http://localhost:3000"><img src="public/images/icone.jpg" alt="gatsbill"></a>
<div id="wrap">
<div id="espacehaut"></div>
<div class="click" id="con" style="display: block;">Se connecter</div>
<div class="click" id="sub" style="display: none;">S'inscrire</div>
<div id="connection" style="display: none;">
<div id="message1" class="message" style="display: none;"></div>
<form action="/connection/" method="post" id="form_connection">
<input type="text" name="login" id="login" placeholder="Login" value="" required="" autofocus="">
<input type="password" name="password" id="password" placeholder="Password" required="">
<input type="submit" name="submit" value="Connect">
</form>
</div>
<div id="subscribe" style="">
<p id="p">Pour vous inscrire,<br> Veuillez remplir les champs ci-dessous</p>
<div id="message2" class="message" style="display: none;"></div>
<form action="/connection/ajouter/" method="post" id="form_inscription">
<input type="text" name="login" placeholder="Login" value="" required="" autofocus="">
<input type="email" name="mail" placeholder="Email" value="" required="">
<input type="password" name="password" placeholder="Password" required="">
<input type="password" name="password2" placeholder="Password" required="">
<input type="submit" name="submit" value="Create account">
</form>
</div>
<div id="espacebas"></div>
</div>
</div>
<!-- Script -->
<script src="http://code.jquery.com/jquery-1.10.1.min.js"></script>
<script type="text/javascript" src="public/js/connection.js"></script>
<script>
$.getJSON( "http://localhost:3000/connection", function(data){
if( data.state ) {
state = parseInt(data.state);
switch (state) {
case 1:
formulaire();
$("#message2").text("login déja utilisé");
break;
case 2:
formulaire();
$("#message2").text("mail déja utilisé");
break;
case 3:
formulaire();
$("#message2").text("Mot de passe trop court");
break;
case 4:
formulaire();
$("#message2").text("mot de passe différent");
break;
case 5:
connect();
$("#message1").text("connection pas ok");
break;
case 6:
connect();
$("#message1").text("vous pouvez maintenant vous connecter");
break;
}
}
});
</script>
</body>
</html>
When i'm trying to subscribe with two different password this is what I have :
当我尝试使用两个不同的密码订阅时，这就是我所拥有的：
A white page with only this :
一个只有这个的白页：
{"state":"4"}
{“状态”：“4”}
And of course this error in node Js console: Can't set headers after they are sent
当然还有节点 Js 控制台中的这个错误：发送后无法设置标头
回答by srquinn
Welcome to nodejs/express!
欢迎使用 nodejs/express！
This is where you are getting your "Can't set headers after they are sent" error in the console:
这是您在控制台中收到“发送后无法设置标头”错误的地方：
// Page connection
app.route('/connection')
.get(function(req, res) {
res.render('index.html',{});
if (req.session.state) {
res.json({state: req.session.state});
}
})
In this configuration, res.renderand res.jsonwill both call res.end()which is basically like trying to send a response twice to the client.
在这种配置中，res.render和res.json都会调用res.end()这基本上就像尝试向客户端发送两次响应一样。
You should place a returnstatement before res.renderor set {state: req.session.state}as the second param to your res.render()call and then use a swig template to display that data.
您应该return在调用之前放置一个语句res.render或将其设置{state: req.session.state}为res.render()调用的第二个参数，然后使用 swig 模板来显示该数据。
回答by akshay
I've solved it this way:
我是这样解决的：
Override res.send in the very first middleware:
在第一个中间件中覆盖 res.send：
app.use(function(req,res,next){
var _send = res.send;
var sent = false;
res.send = function(data){
if(sent) return;
_send.bind(res)(data);
sent = true;
};
next();
});
