如何在 for 循环中连接 Mongoose 查询结果？

Question

我需要将猫鼬查询结果连接到单个 JSON 对象。 问题是我将一个数组传递给 mongoose ie；

Modem Serial: [11111111111,nodata,3333333333333333]

我需要的是像这样连接数据；

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"}]

这是我的代码；

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));

                });
            }

但刷新后我得到了这个，

最终调制解调器：

 [{"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??

这是我的完整代码，

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 循环是同步的，而findOne 是异步的。 findOne 的回调可能不会按照findOne 被触发的顺序被触发。

我会为此使用async.js，尤其是async#mapSeries，因为您似乎正在尝试将一个数组中的每个元素转换为另一个数组，并且您还希望保留顺序。

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);
});