promise - 使用 sequelize 的 promise 循环

Question

我有一个大数组，我想遍历它并对其执行 promise ，但我的循环在 promise 结束之前结束。他们是我可以通过循环 promise 并能够在 promise 循环结束后执行某些事情的一种方式。这是我的代码。

  Meters.getMetersByResidentId(resident.id)
    .then(function(meters){
      _.each(meters, function(meter){
        var meter_obj = {};
        var meter_obj_arr = [];
        Servers.getServerIdByMeterId(meter.id)
        .then(function(server_id){
          Meters.getNameByMeterId(meter.id)
          .then(function(name){
            Dials[server_id[0].server_id].getPreviousTotalByChannelServerAndSN(server_id[0].server_id,name[0].meter_id,billing_id)
            .then(function(previous_total){
              Dials[server_id[0].server_id].getCurrentTotalByChannelServerAndSN(server_id[0].server_id,name[0].meter_id,billing_id)
              .then(function(current_total){
                Promise.all([Billings.getStartDateById(billing_id),Billings.getEndDateById(billing_id)])
                .then(function(result){
                  meter_obj.meter_no = meter.meter_id;
                  if (meter.type == 1)  meter_obj.meter_type = "EL";
                  else if (meter.type == 0) meter_obj.meter_type = "W";
                  meter_obj.days = Math.round(Math.abs((result[0][0].start_date.getTime() - result[1][0].end_date.getTime())/(24*60*60*1000)));
                  meter_obj.prev_read_date = dateFormat(result[0][0].start_date, "mediumDate");
                  meter_obj.current_read_date = dateFormat(result[1][0].end_date,"mediumDate");
                  meter_obj.code = "MR";
                  meter_obj.current_reading = current_total[0].total;
                  meter_obj.prev_reading = previous_total[0].total;
                  meter_obj.multiplier = meter.multiplier;
                  meter_obj.usage = Math.round((meter_obj.current_reading - meter_obj.prev_reading)*meter_obj.multiplier*100)/100;
                  if (meter.type == 1)  meter_obj.units = "KWh";
                  else if (meter.type ==0)   meter_obj.units = "m3"
                  meter_obj_arr.push(meter_obj);
                  invoice_obj.meters = meter_obj_arr;
                });
              });
            });
          });
        });
      });
    });

一旦将所有仪表数据推送到数组中，我想显示 invoice_obj。

Answer 1

Meters.getMetersByResidentId(resident.id)
  .then(function (meters) {
    var metersLoop = []
    
     _.each(meters, function (meter) {
      metersLoop.push(function () {
        return Servers.getServerIdByMeterId(meter.id)
          .then(function (server_id) {
            return Meters.getNameByMeterId(meter.id)
              .then(function (name) {
                return Dials[server_id[0].server_id].getPreviousTotalByChannelServerAndSN(server_id[0].server_id, name[0].meter_id, billing_id)
                  .then(function (previous_total) {
                    return Dials[server_id[0].server_id].getCurrentTotalByChannelServerAndSN(server_id[0].server_id, name[0].meter_id, billing_id)
                      .then(function (current_total) {
                        return Promise.all([Billings.getStartDateById(billing_id), Billings.getEndDateById(billing_id)])
                          .then(function (result) {
                            var meter_obj = {
                              meter_no: meter.meter_id,
                              days: Math.round(Math.abs((result[0][0].start_date.getTime() - result[1][0].end_date.getTime()) / (24 * 60 * 60 * 1000))),
                              prev_read_date: dateFormat(result[0][0].start_date, "mediumDate"),
                              current_read_date: dateFormat(result[1][0].end_date, "mediumDate"),
                              code: "MR",
                              current_reading: current_total[0].total,
                              prev_reading: previous_total[0].total,
                              multiplier: meter.multiplier,
                              usage: Math.round((meter_obj.current_reading - meter_obj.prev_reading) * meter_obj.multiplier * 100) / 100
                            }

                            if (meter.type == 1) meter_obj.meter_type = "EL";
                            else if (meter.type == 0) meter_obj.meter_type = "W";

                            if (meter.type == 1) meter_obj.units = "KWh";
                            else if (meter.type == 0) meter_obj.units = "m3"

                            return meter_obj
                          })
                      })
                  })
              })
          })
      })
    })

    return Promise.all(metersLoop)
  }).then(function (meter_obj_arr) {
    console.log(meter_obj_arr)
  })
})