Ошибка сохранения узла «Невозможно установить заголовки после их отправки»

Question

Я видел эту проблему несколько раз в SO и в других местах, но все равно не мог заставить мой код работать. При попытке создать новый документ в узле из запроса POST я получаю следующую ошибку:

_http_outgoing.js:346 
    throw new Error('Can\'t set headers after they are sent.'); 
    ^

Error: Can't set headers after they are sent. 
    at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:346:11) 
    at ServerResponse.header (/Users/joshuaswiss/CGA-Code/Transfers/mean-transfers/api/node_modules/express/lib/response.js:718:10) 
    at ServerResponse.send (/Users/joshuaswiss/CGA-Code/Transfers/mean-transfers/api/node_modules/express/lib/response.js:163:12) 
    at ServerResponse.json (/Users/joshuaswiss/CGA-Code/Transfers/mean-transfers/api/node_modules/express/lib/response.js:249:15) 
    at /Users/joshuaswiss/CGA-Code/Transfers/mean-transfers/api/controllers/transfersController.js:23:12 
    at /Users/joshuaswiss/CGA-Code/Transfers/mean-transfers/api/node_modules/mongoose/lib/document.js:1743:19 
    at handleError (/Users/joshuaswiss/CGA-Code/Transfers/mean-transfers/api/node_modules/hooks-fixed/hooks.js:40:22) 
    at _next (/Users/joshuaswiss/CGA-Code/Transfers/mean-transfers/api/node_modules/hooks-fixed/hooks.js:46:22) 
    at fnWrapper (/Users/joshuaswiss/CGA-Code/Transfers/mean-transfers/api/node_modules/hooks-fixed/hooks.js:186:18) 
    at /Users/joshuaswiss/CGA-Code/Transfers/mean-transfers/api/node_modules/mongoose/lib/schema.js:234:13 
    at complete (/Users/joshuaswiss/CGA-Code/Transfers/mean-transfers/api/node_modules/mongoose/lib/document.js:1128:7) 
    at /Users/joshuaswiss/CGA-Code/Transfers/mean-transfers/api/node_modules/mongoose/lib/document.js:1157:20 
    at ObjectId.SchemaType.doValidate (/Users/joshuaswiss/CGA-Code/Transfers/mean-transfers/api/node_modules/mongoose/lib/schematype.js:654:22) 
    at /Users/joshuaswiss/CGA-Code/Transfers/mean-transfers/api/node_modules/mongoose/lib/document.js:1153:9 
    at doNTCallback0 (node.js:428:9) 
    at process._tickCallback (node.js:357:13) 
[nodemon] app crashed - waiting for file changes before starting... 

Мой код ниже. Когда я console.log request.body, я получаю [object Object], а когда я регистрирую JSON.stringify(request.body), я получаю свой объект, который хочу. Я пробовал играть с добавлением возврата в transfer.save, поскольку ошибка в этом, но не могла заставить его работать. Любая помощь приветствуется!

app.js

var express    = require('express'); 
var app     = express(); 
var logger    = require('morgan'); 
var mongoose    = require('mongoose'); 
var cookieParser   = require('cookie-parser'); 
var bodyParser   = require('body-parser'); 
var multer    = require('multer'); 
var path     = require('path'); 
var ejs     = require('ejs'); 
var cors     = require('cors'); 
var passport    = require('passport'); 
var port     = process.env.PORT || 3000; 

mongoose.connect('mongodb://localhost:27017/rsstransfers'); 

var routes = require('./config/routes'); 

app.use(cors()); 
app.use(logger('dev')); 
app.use(bodyParser.json({limit: '50mb'})); 
app.use(bodyParser.urlencoded({limit: '50mb', extended: true, parameterLimit: 5000})); 
app.use(routes); 

//runs server on port 3000 
app.listen(3000, function() { 
     console.log('server has been started on port %s', port); 
}); 

transferController.js

var Transfer = require('../models/Transfer'); 

//Get all transfers 
function getAll(request, response) { 
    Transfer.find(function(error, transfers) { 
     if(error) response.json({message: 'couldn\'t find any transfers'}); 

     response.json({ transfers: transfers }); 
    }).select('-__v'); 
} 

//Create a new transfer 
function createTransfer(request, response) { 
    console.log('posting'); 
    console.log('body: ' + request.body); 
    console.log(JSON.stringify(request.body)); 

    var transfer = new Transfer(request.body); 
    debugger; 
    transfer.save(function(error) { 
     if(error) response.json({ message: 'could not create transfer because ' + error }); 

     response.json({ transfer: transfer }); 
    }); 
} 

//Delete 
function removeTransfer(request, response) { 
    var id = request.params.id; 

    Transfer.remove({_id: id}, function(error) { 
    if(error) response.json({message: 'Could not delete transfer b/c:' + error}); 

    response.json({message: 'Transfer successfully deleted'}); 
    }).select('-__v'); 
} 

module.exports = { 
    getAll: getAll, 
    createTransfer: createTransfer, 
    removeTransfer: removeTransfer 
} 

Answer 1

Вы отправляете ответ дважды. Add return

//don't forget to return the error, otherwise you send response twice 
if (error) return response.json({message: 'Could not delete transfer b/c:' + error}); 

response.json({message: 'Transfer successfully deleted'});