在Nodejs中获取未定义的variables

我正在使用Node来运行此代码

但是当我运行这个代码得到在get函数中的leadidvariables的未定义的返回：

call = {}; call.hangup = { get: function(isOpen, ami, elastic, validator, growly, mysql, request){ var self = call.hangup; this.isOpen = isOpen; this.ami = ami; this.elastic = elastic; this.validator = validator; this.growly = growly; this.mysql = mysql; this.request = request; if(isOpen) { ami.on('hangup', function(evt){ var cause_status = parseInt(evt.cause); var message = self.causeStatus(cause_status); var channel = evt.channel; var isDAHDI = validator.contains(channel,"DAHDI"); if((isDAHDI)&&(cause_status == 16)) { var mobile = evt.calleridnum; if(validator.isLength(mobile,11)) { if(validator.matches(mobile,/^09/i)) { var txtMessage = ""; var sending = ""; var leadid = self.searching(mobile, mysql, validator); retrun leadid; /// get the undefined !!!! } } } }); }else { console.log("Hangup's Event is OFF !"); } }, searching: function(number, mysql, validator){ this.number = number; this.mysql = mysql; this.validator = validator; var query = "{sql ...}"; mysql.query(query, function(err, rows, fields) { if (err) throw err; if(!validator.isNull(rows)) { return rows[0].leadid; }else { return false; } }); }, }; module.exports = call; 

这是我如何在主文件中调用它：

 var call = require('./call'); call.hangup.get(true, ami, client, validator, growly, connection, request); 

在另一方面，当我在主文件中调用这个函数（search）时

 new call.hangup.searching(number, connection, validator); 

它工作正常

我该如何解决？

Answer 1

你需要记住JavaScript是asynchronous的。

当searching被调用时，数据库查询是asynchronous发出的，函数返回，然后数据库会给你一个结果。 换句话说，你的searchingfunction不会给你的结果

 function(err, rows, fields) { if (err) throw err; if(!validator.isNull(rows)) { return rows[0].leadid; }else { return false; } } 

如你所愿，

  searching: function(number, mysql, validator){ this.number = number; this.mysql = mysql; this.validator = validator; var query = "{sql ...}"; mysql.query(query, function(err, rows, fields) { if (err) throw err; if(!validator.isNull(rows)) { return rows[0].leadid; }else { return false; } }); --- > This is reached at the end of the call and nothing is returned }, }; 

它不显式返回任何东西，因此undefined 。

您应该使用promises或通过searching一个callback函数，当您的数据库查询返回时将被调用。

所以你的解决scheme应该是这样的：

 get: function (...){ ... self.searching(mobile, mysql, validator, whatIwantToDoAfterValidation) }, searching: function(number, mysql, validator, callback){ ... mysql.query(..., callback){ if(!validator.isNull(rows)) { callback(rows[0].leadid); }else { callback(false); } } }, whatIwantToDoAfterValidation: function(leadid){ ...do whatever you want with leadid... } 

看看jquery's promises ， jquery's promises做同样的事情。