节点JS/Express应用程序 - 调用函数中的一个函数

Question

背景信息

我有一个连接到数据库的Redis查询值的列表中的节点/ Express应用程序。然后对于返回数据中的每个值，我需要进一步查询。

问题

初始查询（Redis的“扫描”命令）工作正常，但如预期的那样HGETALL查询我试图在初步结果集的每个项目不行为。

为了演示这个问题，我在第34行添加了一个console.log命令来打印出当前扫描记录的值......然后在HGETALL的回调函数（第36行）中再次打印出来，但价值是不同的。在我看来，它们应该是一样的......但我确定这是node.js工作方式的基础，我错过了。

代码

27 router.get('/', function(req, res, next) { 
28   redis.send_command("SCAN", [0,"MATCH", "emergency:*"], function(err, reply) { 
29     if (reply) { 
30       var retdata = []; 
31       console.log('length is: ' + reply[1].length); 
32       for (var i = 0; i < reply[1].length; i++) { 
33         var emergIP = reply[1][i]; 
34         console.log('emergIP outside the call: ' + emergIP); 
35         redis.hgetall(emergIP, function (err, data) { 
36           console.log('emergIP inside the call: ' + emergIP); 
37           if (data) {    
38             var temp = emergIP.split(":"); 
39             var key = temp[1]; 
40             console.log('the key is: ' + key); 
41             //retdata.push({key:data.callerid}); 
42           } 
43         }); 
44       }//end for loop 
45       res.send(JSON.stringify(retdata)); 
46     } //end if 
47     else { 
48       //no emergency data defined yet 
49       var retval = {"res":false, "msg":"no emergency data defined"}; 
50       res.send(JSON.stringify(retval)); 
51     
52     }    
53   }); //end send_command 
54 }); 
55 

从代码输出

length is: 8 
emergIP outside the call: emergency:10.1 
emergIP outside the call: emergency:10.2 
emergIP outside the call: emergency:10.13 
emergIP outside the call: emergency:10.14 
emergIP outside the call: emergency:10.18.90 
emergIP outside the call: emergency:10.19 
emergIP outside the call: emergency:10.20 
emergIP outside the call: emergency:10.244 
GET /emergency/ 200 220.368 ms - 2 
emergIP inside the call: emergency:10.244 
the key is: 10.244 
emergIP inside the call: emergency:10.244 
the key is: 10.244 
emergIP inside the call: emergency:10.244 
the key is: 10.244 
emergIP inside the call: emergency:10.244 
the key is: 10.244 
emergIP inside the call: emergency:10.244 
the key is: 10.244 
emergIP inside the call: emergency:10.244 
the key is: 10.244 
emergIP inside the call: emergency:10.244 
the key is: 10.244 
emergIP inside the call: emergency:10.244 
the key is: 10.244 

问题

我认为问题是，我期待在send_command功能回调顺序发生。换句话说，也许问题是我不应该在另一个函数调用中进行函数调用？ 这是我的第一个节点应用程序...我正在学习。

任何建议，将不胜感激。

Answer 1

除了使用async.forEach你可以利用关闭，并立即调用的函数：

// get all elements from redis 
function getAll(emergIP, callback) { 
    redis.hgetall(emergIP, function (err, data) { 
    if (err) { 
     return callback(err); 
    } 

    console.log('emergIP inside the call: ' + emergIP); 
    if (data) { 
     var temp = emergIP.split(":"); 
     var key = temp[1]; 
     console.log('the key is: ' + key); 
    } 

    return callback(null, data); 
    }); 
} 

// Iterate all over the results 
function getResults (reply, callback) { 
    var retdata = []; 
    console.log('length is: ' + reply.length); 
    var length = reply.length; 

    if (!length) { 
    return callback(null, retdata); 
    } 

    for (var i = 0; i < length; i++) { 
    var emergIP = [i]; 
    console.log('emergIP outside the call: ' + emergIP); 

    (function (emergIP, i) { 
     getAll(emergIP, function (err, data) { 
     if (err) { 
      // @todo: how would you like to handle the error? 
     } 

     retdata.push({key:data.callerid}); 

     if (i === length - 1) { 
      return callback(null, retdata); 
     } 
     }); 
    }(emergIP, i)); 
    } //end for loop 
} 

router.get('/', function (req, res, next) { 
    redis.send_command("SCAN", [0, "MATCH", "emergency:*"], function (err, reply) { 
    if (reply) { 
     getResults(reply[1], function (err, data) { 
     if (err) { 
      // @todo: how would you like to handle this in case of error? 
     } 

     res.send(JSON.stringify(data)); 
     }); 
    } //end if 
    else { 
     //no emergency data defined yet 
     var retval = { "res": false, "msg": "no emergency data defined" }; 
     res.send(JSON.stringify(retval)); 

    } 
    }); //end send_command 
}); 

编辑

我修改了一下代码返回当迭代完成时json。这不是完美的代码，因为在这种情况下，如果没有迭代结果，它将根本不会返回客户端的响应。考虑使用async.each：http://caolan.github.io/async/docs.html#.each

EDIT2

我试着去耦代码，并将其分成功能。您可以将这些功能移到另一个文件，然后将它们请求到路由器中。很抱歉，如果有任何不允许代码正常运行的错字，我实际上并没有尝试运行它。