CODEWITHSUNDEEP
javascriptnode.jsexpressamqpnode-amqp
user1640492
user1640492

Reputation:

Error: Can't set headers after they are sent. RabbitMQ interfering with NodeJS response

After a http response, I am sending a messing using RabbitMQ (creating a channel etc) and however, the server is complaining that "Error: Can't set headers after they are sent."

Here is the code:

var amqp = require('amqplib');
var when = require('when');

var rabbitmq_conn = amqp.connect('amqp://localhost' );

function push_keystroke_data(session_id, data) {
  var QUEUE_NAME = 'hello';
  var msg = session_id;

  when(rabbitmq_conn.createChannel()).then(function(ch) {
    var ok = ch.assertQueue(QUEUE_NAME, {durable: false});

    ok.then(function(_qok) {
      ch.sendToQueue(QUEUE_NAME, new Buffer(msg));
      console.log(" [x] Sent '%s'", msg);
      ch.close();
    });

  }).ensure(function() {
    conn.close();
  });
}

router.post('/', function(req, res, next) {

  // current session id
  var sid;

  if (req.cookies.papi) {
    sid = req.cookies.papi.session_id;
  } else {
    sid = generate_session_id();
    res.cookie('papi', {session_id: sid}, {maxAge: COOKIE_MAX_AGE});
  }

  res.send(JSON.stringify({ user_id: get_user_id(sid)}));

  var data = process_keystroke_data(req.body);
  push_keystroke_data(sid, data);

});

I assuming RabbitMQ is setting the headers after the response (I have also tried sending the RabbitMQ message before the response but that also didn't solve anything).

Here is the stack trace:

POST /api 500 220.100 ms - 16
Error: Can't set headers after they are sent.
    at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:335:11)
    at ServerResponse.header (/Users/mikeecb/Documents/KeyNA/jsbackend/node_modules/express/lib/response.js:700:10)
    at ServerResponse.send (/Users/mikeecb/Documents/KeyNA/jsbackend/node_modules/express/lib/response.js:154:12)
    at fn (/Users/mikeecb/Documents/KeyNA/jsbackend/node_modules/express/lib/response.js:934:10)
    at View.exports.renderFile [as engine] (/Users/mikeecb/Documents/KeyNA/jsbackend/node_modules/jade/lib/index.js:374:12)
    at View.render (/Users/mikeecb/Documents/KeyNA/jsbackend/node_modules/express/lib/view.js:93:8)
    at EventEmitter.app.render (/Users/mikeecb/Documents/KeyNA/jsbackend/node_modules/express/lib/application.js:566:10)
    at ServerResponse.res.render (/Users/mikeecb/Documents/KeyNA/jsbackend/node_modules/express/lib/response.js:938:7)
    at /Users/mikeecb/Documents/KeyNA/jsbackend/app.js:62:7
    at Layer.handle_error (/Users/mikeecb/Documents/KeyNA/jsbackend/node_modules/express/lib/router/layer.js:58:5)

Any solutions or ideas would be much appreciated.

Upvotes: 0

Views: 921

Answers (1)

user1640492
user1640492

Reputation:

It turns out that the issue was not that RabbitMQ was setting the headers (which would be weird, why would it be doing any http stuff?) but that after responding res.send(JSON.stringify({ user_id: get_user_id(sid)}));, I tried to send another respond which obviously the issue.

Upvotes: 1

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