如何在for循環中連接Mongoose查詢結果？

Question

我需要連接mongoose查詢結果到單個JSON對象。 問題是我傳遞一個數組到貓鼬即;

Modem Serial: [11111111111,nodata,3333333333333333] 

我需要的是連接這樣的數據;

Final Modem : [{"m_model":"Modem 1","m_serial_no":"11111111111","available":"dispatched"}, 
{"m_model":"No data","m_serial_no":"No data"}, 
{"m_model":"Modem3","m_serial_no":"3333333333333333","available":"dispatched"}] 

這是我的代碼;

for(i=0;i<modem_serial.length;i++){ 
     console.log("Modem Serial: "+modem_serial[i]); 
     Modem.findOne({m_serial_no: modem_serial[i]},{_id: 0,__v:0},function (err,m_data) { 
        //console.log("err: "+err); 
        if(m_data!=null){ 
         modem=modem.concat(m_data); 
        }else{ 
         console.log("\n\n\nm_data : "+m_data); 
         modem=modem.concat({ 
          m_model: 'No data', 
          m_serial_no: 'No data' 
         }); 
        } 
        console.log("\n\n\nFinal Modem : "+JSON.stringify(modem)); 

       }); 
      } 

但刷新後我得到這個，

最終調制解調器：

[{"m_model":"No data","m_serial_no":"No data"},{"m_model":"Modem 1","m_serial_no":"11111111111","available":"dispatched"},{"m_model":"Modem 3","m_serial_no":"3333333333333333","available":"dispatched"}] 


the `No data` is going to first index. why?? 

這裏是我的完整代碼，

router.get('/', function(req, res, next) { 
Dispatched.find({status:"installed"},function(err,dispatched_data) { 
    //console.log("SUCCES data: "+dispatched_data); 
    var client_name=[],branch_name=[],serial=[],data_card_serial=[],sim_number=[],modem_serial=[],idu_serial=[],installed_date=[], 
     ip_address=[],notes=[],ir_report=[],date,ipp={},ip=[],ir,note; 
    for (var j = 0; j < dispatched_data.length; j++) { 
      client_name=client_name.concat([{client_name:dispatched_data[j].client_name}]); 
      branch_name.push(dispatched_data[j].branch_name); 
      serial.push(dispatched_data[j].router_serial); 
      data_card_serial.push(dispatched_data[j].data_card_serial); 
      sim_number.push(dispatched_data[j].sim_number); 
      if(dispatched_data[j].modem_serial != null){ 
       modem_serial.push(dispatched_data[j].modem_serial); 
      }else{ 
       modem_serial.push("nodata"); 
      } 

      idu_serial.push(dispatched_data[j].idu_serial); 
      ip_address.push({ip_address:dispatched_data[j].ip_address}); 
      installed_date.push({installed_date:dispatched_data[j].installation_date}); 
      notes.push({notes:dispatched_data[j].notes}); 
      ir_report.push({ir_report:dispatched_data[j].ir_report}); 
     } 
var data=[],router=[],datacard=[],sim=[],modem=[],idu=[],branch=[],i; 
    console.log("Modem Serial: "+modem_serial.toString()); 
    console.log("\n\n\nDispatched Data Length ="+dispatched_data.length); 
    for(i=0;i<modem_serial.length;i++){ 
     console.log("Modem Serial: "+modem_serial[i]); 
     Modem.findOne({m_serial_no: modem_serial[i]},{_id: 0,__v:0},function (err,m_data) { 
        //console.log("err: "+err); 
        if(m_data!=null){ 
         modem=modem.concat(m_data); 
        }else{ 
         console.log("\n\n\nm_data : "+m_data); 
         modem=modem.concat({ 
          m_model: 'No data', 
          m_serial_no: 'No data' 
         }); 
        } 
        console.log("\n\n\nFinal Modem : "+JSON.stringify(modem)); 

       }); 
      } 
res.end(); 
}); 
}); 

Answer 1

for環路是同步的，而findOne是異步的。 findOne的回調可能不會在findOne被解僱的訂單中被解僱。

我會使用async.js這個，特別是async#mapSeries，因爲你似乎試圖將一個數組中的每個元素轉換爲另一個數組，並且您還想保留該順序。

async.mapSeries(modem_serial, function (m_serial_no, done) { 
    Modem.findOne({ m_serial_no: m_serial_no }, { _id: 0, __v:0 }, function (err, m_data) { 
     // if an error occurs, stop everything 
     if (err) 
      return done(err); 
     // if a modem is found, send it back 
     if (m_data) 
      return done(null, m_data); 
     // otherwise 
     done(null, { m_model: 'No data', m_serial_no: 'No data' }); 
    }); 
}, function (err, modems) { 
    // when the iteration is done or if an error occurred, it will come here 
    console.log(err, modems); 
});