NodeJS返回响应时出错

Question

我正在制作一个简单的Rest服务，它必须将JSON请求中的数据添加到数据库（MongoDB）中。当我向服务发出请求时出现问题,服务器会出现以下错误：

Controller@0.0.0start C:\users\Fernando\Google Drive\tcc_Fernando_Felipe\Controller\Controller节点./bin/www

{[Error：找不到模块“../build/release/bson”]代码：“module_not_found”}JS-bson：无法加载C++bson扩展，使用纯JS版本POST/controller/addagent 200 25.762ms-0_http_outgoing。JS：335抛出新错误（“发送头后不能\设置头。”）；^错误：发送后无法设置标头。在serverresponse.outgoingMessage.setheader(_http_outgoing.js:335:11)在serverresponse.header(C:\users\fernando\google drive\tcc_fernando_felipe\controller\controller\node_module\express\lib\response.js:718:10)在serverresponse.send(C:\users\fernando\google(C:\Users\Fernando\Google Drive\TCC_Fernando_Felipe\Controller\Controller\Routers\Controller.js:26:15)。(c:\users\fernando\fernando\google drive\tcc_fernando_felipe\controller\controller\node_module\monk\node_module\mpromise\lib\promise.js:178:8)在promise.emit(events.js:129:20)在promise.emit(C:\users\fernando\google

npm错误！Windows_NT 6.3.9600 npm错误！argv“C:\nodejs\\node.exe”“C:\nodejs\node_modules\npm\bin\npm-cli.js”“start”npm错误！节点V0.12.7 npm错误！npm V2.11.3 npm错误！代码ELIFECYCLE npm错误！controller@0.0.0start:node./bin/wwwnpm错误！退出状态%1 npm错误！npm错误！控制器@0.0.0启动脚本“node./bin/www”失败。npm错误！这很可能是控制器包的问题，npm错误！而不是国家预防机制本身。npm错误！告诉作者这在您的系统上失败：npm err！节点。/bin/www npm错误！您可以通过以下途径获得他们的信息：npm err！npm所有者ls控制器npm错误！上面可能有其他日志记录输出。

npm错误！请在任何支持请求中包括以下文件：npm错误！C:\users\fernando\google drive\tcc_fernando_felipe\controller\controller\npm-debug.log

服务器端的代码是：

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;

应用程序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;

错误似乎是由下面的行块引起的。我不知道为什么，因为只有在那一刻才访问res变量。

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

Answer 1

您正在使用res.send（）多次发送数据，因此会出现此错误。试试这个：

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: '' }
                 );
              }
            }
        });
    }
}


});