NodeJS發送響應時出錯

Question

我正在做一個簡單的Rest服務，它必須向數據庫（MongoDB）中添加JSON請求中的數據。當我提出到服務請求的問題正在發生，該服務器發生故障，出現以下錯誤：

controller@0.0.0 start C:\Users\Fernando\Google Drive\TCC_Fernando_Felipe\Controller\controller node ./bin/www

{ [Error: Cannot find module '../build/Release/bson'] code: 'MODULE_NOT_FOUND' } js-bson: Failed to load c++ bson extension, using pure JS version POST /controller/addagent 200 25.762 ms - 0 _http_outgoing.js:335 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:335:11) at ServerResponse.header (C:\Users\Fernando\Google Drive\TCC_Fernando_Felipe\Controller\controller\node_modules\express\lib\response.js:718:10) at ServerResponse.send (C:\Users\Fernando\Google Drive\TCC_Fernando_Felipe\Controller\controller\node_modules\express\lib\response.js:163:12) at Promise. (C:\Users\Fernando\Google Drive\TCC_Fernando_Felipe\Controller\controller\routes\controller.js:26:15) at Promise. (C:\Users\Fernando\Google Drive\TCC_Fernando_Felipe\Controller\controller\node_modules\monk\node_modules\mpromise\lib\promise.js:178:8) at Promise.emit (events.js:129:20) at Promise.emit (C:\Users\Fernando\Google Drive\TCC_Fernando_Felipe\Controller\controller\node_modules\monk\node_modules\mpromise\lib\promise.js:84:38) at Promise.fulfill (C:\Users\Fernando\Google Drive\TCC_Fernando_Felipe\Controller\controller\node_modules\monk\node_modules\mpromise\lib\promise.js:97:20) at Promise.resolve (C:\Users\Fernando\Google Drive\TCC_Fernando_Felipe\Controller\controller\node_modules\monk\node_modules\mpromise\lib\promise.js:126:15) at Immediate._onImmediate (C:\Users\Fernando\Google Drive\TCC_Fernando_Felipe\Controller\controller\node_modules\monk\lib\collection.js:343:23)

npm ERR! Windows_NT 6.3.9600 npm ERR! argv "C:\nodejs\\node.exe" "C:\nodejs\node_modules\npm\bin\npm-cli.js" "start" npm ERR! node v0.12.7 npm ERR! npm v2.11.3 npm ERR! code ELIFECYCLE npm ERR! controller@0.0.0 start: node ./bin/www npm ERR! Exit status 1 npm ERR! npm ERR! Failed at the controller@0.0.0 start script 'node ./bin/www'. npm ERR! This is most likely a problem with the controller package, npm ERR! not with npm itself. npm ERR! Tell the author that this fails on your system: npm ERR! node ./bin/www npm ERR! You can get their info via: npm ERR! npm owner ls controller npm ERR! There is likely additional logging output above.

npm ERR! Please include the following file with any support request: npm ERR! C:\Users\Fernando\Google Drive\TCC_Fernando_Felipe\Controller\controller\npm-debug.log

在服務器端的代碼是：

controller.js

var express = require('express'); 
var router = express.Router(); 

/* GET users listing. */ 
router.get('/', function(req, res, next) { 
    res.send('respond with a controller'); 
}); 

/* 
* POST to adduser. 
*/ 
**router.post('/addagent', function(req, res) { 
    var db = req.db; 
    var collection = db.get('controller'); 
    var agents = req.body.agents; 

    if(agents.length && agents.length >0) 
    { 
     for(var i=0; i < agents.length; ++i){ 
       var cAgent = agents[i]; 

       collection.insert(cAgent, function(err, result){ 
       res.send(
        (err === null) ? { msg: '' } : { msg: err } 
       ); 
      }); 
     } 
    } 


});** 

module.exports = router; 

app.js

var express = require('express'); 
var path = require('path'); 
var favicon = require('serve-favicon'); 
var logger = require('morgan'); 
var cookieParser = require('cookie-parser'); 
var bodyParser = require('body-parser'); 

//Added for database connection 
var mongo=require('mongodb'); 
var monk = require('monk'); 
var db = monk('localhost:27017/controller'); 


var routes = require('./routes/index'); 
var users = require('./routes/users'); 
var controller = require('./routes/controller') 

var app = express(); 

// view engine setup 
app.set('views', path.join(__dirname, 'views')); 
app.set('view engine', 'jade'); 

// uncomment after placing your favicon in /public 
//app.use(favicon(path.join(__dirname, 'public', 'favicon.ico'))); 
app.use(logger('dev')); 
app.use(bodyParser.json()); 
app.use(bodyParser.urlencoded({ extended: false })); 
app.use(cookieParser()); 
app.use(express.static(path.join(__dirname, 'public'))); 

// Make our db accessible to our router 
app.use(function(req,res,next){ 
    req.db = db; 
    next(); 
}); 


app.use('/', routes); 
app.use('/users', users); 
app.use('/controller',controller); 

// catch 404 and forward to error handler 
app.use(function(req, res, next) { 
    var err = new Error('Not Found'); 
    err.status = 404; 
    next(err); 
}); 

// error handlers 

// development error handler 
// will print stacktrace 
if (app.get('env') === 'development') { 
    app.use(function(err, req, res, next) { 
    res.status(err.status || 500); 
    res.render('error', { 
     message: err.message, 
     error: err 
    }); 
    }); 
} 

// production error handler 
// no stacktraces leaked to user 
app.use(function(err, req, res, next) { 
    res.status(err.status || 500); 
    res.render('error', { 
    message: err.message, 
    error: {} 
    }); 
}); 


module.exports = app; 

該錯誤似乎是由下面的行塊引起的。我不知道爲什麼，因爲res變量只能在那個時候訪問。

res.send(
        (err === null) ? { msg: '' } : { msg: err } 
       ); 

Answer 1

您使用res.send（）多次發送數據，因此發生此錯誤。 試試這個：

router.post('/addagent', function(req, res) { 
var db = req.db; 
var collection = db.get('controller'); 
var agents = req.body.agents; 
var count=1; 
if(agents.length && agents.length >0) 
{ 
    for(var i=0; i < agents.length; ++i){ 
      var cAgent = agents[i]; 

      collection.insert(cAgent, function(err, result){ 
      if(err) 
       res.send({ msg: err }); 
      else{ 
       count++; 
       if(count== agents.length){ 
       res.send(
        { msg: '' } 
       ); 
       } 
      } 
     }); 
    } 
} 


}); 

Answer 2

我發現這個問題，它是因爲，它試圖多次發送res.send（）。