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2023-04-10 08:00:04

错误:发送到客户端后无法设置标头

我对Node.js相当陌生，我有一些问题。

我使用的是Node.js 4.10和Express 2.4.3。

当我尝试访问http://127.0.0.1:8888/auth/facebook时，我将被重定向到http://127.0.0.1:8888/auth/facebook_callback。

然后我收到以下错误:

Error: Can't render headers after they are sent to the client.
    at ServerResponse.<anonymous> (http.js:573:11)
    at ServerResponse._renderHeaders (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/patch.js:64:25)
    at ServerResponse.writeHead (http.js:813:20)
    at /home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect-auth/lib/auth.strategies/facebook.js:28:15
    at /home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect-auth/lib/index.js:113:13
    at next (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect-auth/lib/strategyExecutor.js:45:39)
    at [object Object].pass (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect-auth/lib/authExecutionScope.js:32:3)
    at [object Object].halt (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect-auth/lib/authExecutionScope.js:29:8)
    at [object Object].redirect (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect-auth/lib/authExecutionScope.js:16:8)
    at [object Object].<anonymous> (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect-auth/lib/auth.strategies/facebook.js:77:15)
Error: Can't set headers after they are sent.
    at ServerResponse.<anonymous> (http.js:527:11)
    at ServerResponse.setHeader (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/patch.js:50:20)
    at next (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/http.js:162:13)
    at next (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/http.js:195:11)
    at next (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/http.js:150:23)
    at param (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/middleware/router.js:189:13)
    at pass (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/middleware/router.js:191:10)
    at Object.router [as handle] (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/middleware/router.js:197:6)
    at next (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/http.js:198:15)
    at Object.auth [as handle] (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect-auth/lib/index.js:153:7)
Error: Can't set headers after they are sent.
    at ServerResponse.<anonymous> (http.js:527:11)
    at ServerResponse.setHeader (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/patch.js:50:20)
    at next (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/http.js:162:13)
    at next (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/http.js:207:9)
    at next (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/http.js:150:23)
    at param (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/middleware/router.js:189:13)
    at pass (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/middleware/router.js:191:10)
    at Object.router [as handle] (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/middleware/router.js:197:6)
    at next (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/http.js:198:15)
    at Object.auth [as handle] (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect-auth/lib/index.js:153:7)
Error: Can't set headers after they are sent.
    at ServerResponse.<anonymous> (http.js:527:11)
    at ServerResponse.setHeader (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/patch.js:50:20)
    at next (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/http.js:162:13)
    at next (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/http.js:150:23)
    at next (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/http.js:207:9)
    at Object.auth [as handle] (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect-auth/lib/index.js:153:7)
    at next (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/http.js:198:15)
    at HTTPServer.handle (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/http.js:211:3)
    at Object.handle (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/http.js:105:14)
    at next (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/http.js:198:15)
Error: Can't set headers after they are sent.
    at ServerResponse.<anonymous> (http.js:527:11)
    at ServerResponse.setHeader (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/patch.js:50:20)
    at next (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/http.js:162:13)
    at next (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/http.js:150:23)
    at next (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/http.js:207:9)
    at HTTPServer.handle (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/http.js:211:3)
    at Object.handle (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/http.js:105:14)
    at next (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/http.js:198:15)
    at /home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/middleware/session.js:323:9
    at /home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/middleware/session.js:338:9

node.js:134
        throw e; // process.nextTick error, or 'error' event on first tick
        ^
Error: Can't set headers after they are sent.
    at ServerResponse.<anonymous> (http.js:527:11)
    at ServerResponse.setHeader (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/patch.js:50:20)
    at next (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/http.js:162:13)
    at next (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/http.js:207:9)
    at /home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/middleware/session.js:323:9
    at /home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/middleware/session.js:338:9
    at Array.<anonymous> (/home/eugene/public_html/all_things_node/projects/fb2/node_modules/connect/lib/middleware/session/memory.js:57:7)
    at EventEmitter._tickCallback (node.js:126:26)

以下是我的代码:

var fbId= "XXX";
var fbSecret= "XXXXXX";
var fbCallbackAddress= "http://127.0.0.1:8888/auth/facebook_callback"

var cookieSecret = "node";     // enter a random hash for security

var express= require('express');
var auth = require('connect-auth')
var app = express.createServer();


app.configure(function(){
    app.use(express.bodyParser());
    app.use(express.methodOverride());
    app.use(express.cookieParser());
    app.use(express.session({secret: cookieSecret}));
    app.use(auth([
        auth.Facebook({
            appId : fbId,
            appSecret: fbSecret,
            callback: fbCallbackAddress,
            scope: 'offline_access,email,user_about_me,user_activities,manage_pages,publish_stream',
            failedUri: '/noauth'
        })
    ]));
    app.use(app.router);
});


app.get('/auth/facebook', function(req, res) {
  req.authenticate("facebook", function(error, authenticated) {
    if (authenticated) {
      res.redirect("/great");
      console.log("ok cool.");
      console.log(res['req']['session']);
    }
  });
});

app.get('/noauth', function(req, res) {
  console.log('Authentication Failed');
  res.send('Authentication Failed');
});

app.get('/great', function( req, res) {
  res.send('Supercoolstuff');
});

app.listen(8888);

我可以知道我的代码有什么问题吗?

当前回答

有一段时间我也遇到了这个错误。我想(希望)我已经想明白了，想把它写在这里供参考。

当你使用app.use方法添加中间件来连接或表达(建立在connect上)时，你在connect中将项目附加到Server.prototype.stack中(至少在当前的npm install connect中，它看起来与本文的github有很大不同)。当服务器收到请求时，它遍历堆栈，调用(request, response, next)方法。

问题是，如果在一个中间件项目中写入响应体或报头(出于某种原因，它看起来像是/或)，但没有调用response.end()，而是调用next()，然后作为核心Server.prototype.handle方法完成，它将注意到:

堆栈中没有更多的项，和/或 这种反应。headerSent为true。

因此，它抛出一个错误。但是它抛出的错误只是这个基本的响应(来自connect http.js源代码:

res.statusCode = 404;
res.setHeader('Content-Type', 'text/plain');
res.end('Cannot ' + req.method + ' ' + req.url);

就在那里，它调用res.setHeader('Content-Type'， 'text/plain');，你可能已经在你的渲染方法中设置了，而没有调用response.end()，类似于:

response.setHeader("Content-Type", "text/html");
response.write("<p>Hello World</p>");

所有东西的结构是这样的:

良好的中间件

// middleware that does not modify the response body
var doesNotModifyBody = function(request, response, next) {
  request.params = {
    a: "b"
  };
  // calls next because it hasn't modified the header
  next();
};

// middleware that modify the response body
var doesModifyBody = function(request, response, next) {
  response.setHeader("Content-Type", "text/html");
  response.write("<p>Hello World</p>");
  response.end();
  // doesn't call next()
};

app.use(doesNotModifyBody);
app.use(doesModifyBody);

有问题的中间件

var problemMiddleware = function(request, response, next) {
  response.setHeader("Content-Type", "text/html");
  response.write("<p>Hello World</p>");
  next();
};

有问题的中间件设置响应头时没有调用response.end()，而是调用next()，这会混淆connect的服务器。

2011-10-17 03:38:10

其他回答

在我的情况下，在循环中，我放置res.render()，因此可能已经尝试调用多次。

2020-02-20 04:23:02

就靠这个。你可以通过这个函数传递响应:

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();
});
2015-11-05 07:28:41

当您发送2个响应时发生此错误。例如:

if(condition A)
{ 

      res.render('Profile', {client:client_});

}

if (condition B){

      res.render('Profile', {client:client_});
    }
  }

想象一下，如果由于某种原因，条件A和B为真，那么在第二次渲染中，你会得到这个错误

2019-10-07 10:49:39

在我的例子中，它是一个全局拦截器，设置无缓存头。

2022-06-21 09:09:42

有时，当你试图在res.end或res.send之后调用next()函数时，你可能会得到这个错误，如果你在函数中res.send或res.end之后调用next()，请尝试删除。 注意:这里的next()表示在响应客户端后(i。E res.send或res.end)你仍然试图执行一些代码来再次响应，所以这是不合法的。

例子:

router.get('/',function (req,res,next){
     res.send("request received");
     next(); // this will give you the above exception 
});

从上面的函数中删除next()，它将工作。

2017-03-08 11:54:47

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