小编Kor*_*clü的帖子

我想在后端进行串行工作.我想选择geo_unit并做另一项工作并向客户端写回复.我阅读了 http://nodejs.org/docs/v0.4.7/api/events.html#events和错误:无法在将标题发送到客户端后设置标题

当我慢慢发送请求时,一切正常,例如每3秒发送一次.

但是当我快速发送请求时它不起作用.我得到以下错误.我是否在全球定义了什么？

Error: Can't set headers after they are sent.
    at ServerResponse.OutgoingMessage.setHeader (http.js:691:11)
    at ServerResponse.res.setHeader (E:\git\xxxxxx-nodejs\node_modules\express\node_modules\connect\lib\patch.js:63:22)
    at ServerResponse.res.set.res.header (E:\git\xxxxxx-nodejs\node_modules\express\lib\response.js:527:10)
    at ServerResponse.res.json (E:\git\xxxxxx-nodejs\node_modules\express\lib\response.js:194:36)
    at EventEmitter. (E:\git\xxxxxx-nodejs\routes\api_scrapper.js:17:17)
    at EventEmitter.emit (events.js:117:20)
    at ScrapperAPI.externalLocationCallback (E:\git\xxxxxx-nodejs\routes\api_scrapper.js:27:20)
    at Query._callback (E:\git\xxxxxx-nodejs\routes\api_scrapper.js:51:21)
    at Query.Sequence.end (E:\git\xxxxxx-nodejs\node_modules\mysql\lib\protocol\sequences\Sequence.js:78:24)
    at Query._handleFinalResultPacket (E:\git\xxxxxx-nodejs\node_modules\mysql\lib\protocol\sequences\Query.js:143:8)

我使用以下代码:

var express = require('express'),
  http = require('http'),
  path = require('path');

var app = module.exports = express();
var server = require('http').createServer(app);
var io = require('socket.io').listen(server);
var request = require('request');
var cheerio = require('cheerio');


var mysql = …

我有以下代码.我是nodejs&js的新手

我想在1. log中获取值但是我得到了未定义.只有2.日志输出到日志.

我从回调和 https://github.com/felixge/node-mysql读取nodeJS返回值,但没有关于返回值的示例.

我不知道如何在node-mysql页面中使用给定示例的return语句.

exports.location_internal = function (req, res) {
    var r = getExternalLocation(2);
        // 1. log  
    console.log(r);
    res.send( r);
}

var getExternalLocation = function (id) {
    pool.getConnection(function(err, connection){
      if(err) throw err;

      var response = {};
      connection.query( "select * from external_geo_units where geo_unit_id = "+id,  function(err, rows){
        if(err) throw err;
        response.data= rows;
                // 2. log
        console.log(response);
        return  response;
      });
      connection.release();
    });

};