Promise not working properly when I use inside map using javascript

Question

I'm writing a JavaScript function for handling API calls inside map method, before done all tasks inside map method my function is to execute the wrong result. But it's not working for my expectation.

my code:

function vehicleAndWorker(hook){
  var routeArray = [];
  return new Promise(function(resolve, reject) {
    hook.data.map(d => {
      var routeArray = [];
      delete d.driverId
      delete d.vehicle
      delete d.workers
      return hook.app.service('vehicles')
        .find({ query: {vehicleId: d.vehicleId}})
        .then(result=>{
          var vehicleTypeId = result.data[0].vehicleTypeId;
          return hook.app.service('vehicle-types')
              .find({ query: {vehicleTypeId: vehicleTypeId }})
              .then(result=>{
                  d.vehicle = {
                    vehicleId: d.vehicleId,
                    vehicleTypeId: vehicleTypeId,
                    fixedCost: result.data[0].fixedCost,
                    variableCost: result.data[0].variableCost
                  }
                  return hook.app.service('workers')
                    .find({ query: {assignedVehicleId: d.vehicleId}})
                    .then(result=>{
                        d.workers = [{
                          id:result.data[0].workerId,
                          name:result.data[0].name,
                          type:result.data[0].type
                        }];
                        delete d.vehicleId;
                  })
              })
          })
      })
      resolve(hook)
  })
}

before executing my map job, the return is executed how to resolve this.

Can you try placing **resolve(hook)** after **delete d.vehicleId;** ? — Ketha Kavya, Dec 15 '17 at 13:08
@2oppin, okay you are right. Checked in editor, it's just wrong indentation — Anton Sutarmin, Dec 15 '17 at 13:14

2oppin · Answer 1 · 2017-12-15T13:23:59.323

2

Try to use Promise.all()

Your ".map" call returns a set of Promises. So it returns immidiatly,

function vehicleAndWorker(hook){
    var routeArray = [];
    return new Promise(function(resolve, reject) => 
       Promise.all(hook.data.map(d => {....})
          .then(() => resolve(hook))
    );
 }

As @Akshay mentioned we can even reduce this function code, and move you "map" function in some other, so your vahicle will be single line:

var vehicleAndWorker = (hook) => Promise.all(hook.data.map(d => your_map_function)
              .then(() => hook);

edited Dec 15 '17 at 13:23

answered Dec 15 '17 at 13:16

2oppin

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I think, we can also do without return statement, that's what i did in my answer and move the resolve a line above – Akshay Vijay Jain Dec 15 '17 at 13:18
actually we can convert vehicleAndWorker(hoor) to single line, left so just to keep some similarity – 2oppin Dec 15 '17 at 13:20

score 2 · Accepted Answer · edited Dec 25 '17 at 16:08

first chain your promises and not nest them .if you use nesting then you dont need promise.

second use promise all

function vehicleAndWorker(hook){
    var all = [];
    var i =0;
    hook.data.map(d => {
      delete d.driverId
      delete d.vehicle
      delete d.workers
      all[i] = hook.app.service('vehicles')
        .find({ query: {vehicleId: d.vehicleId}})
        .then(result=>{
              var vehicleTypeId = result.data[0].vehicleTypeId;
              return hook.app.service('vehicle-types').find({ query: {vehicleTypeId: vehicleTypeId }})
         })
        .then(result=>{
            d.vehicle = {
              vehicleId: d.vehicleId,
              vehicleTypeId: vehicleTypeId,
              fixedCost: result.data[0].fixedCost,
              variableCost: result.data[0].variableCost
            }
            return hook.app.service('workers').find({ query: {assignedVehicleId: d.vehicleId}})
         })
        .then(result=>{
            d.workers = [{
              id:result.data[0].workerId,
              name:result.data[0].name,
              type:result.data[0].type
            }];
            delete d.vehicleId;
            return result
         })
          i++;
      })
     return Promise.all(all).then(hook);     
}

score 0 · Answer 3 · answered Dec 15 '17 at 13:12

try this

function vehicleAndWorker(hook){
  var routeArray = [];
  return new Promise(function(resolve, reject) {
    hook.data.map(d => {
      var routeArray = [];
      delete d.driverId
      delete d.vehicle
      delete d.workers
      hook.app.service('vehicles')
        .find({ query: {vehicleId: d.vehicleId}})
        .then(result=>{
          var vehicleTypeId = result.data[0].vehicleTypeId;
          hook.app.service('vehicle-types')
              .find({ query: {vehicleTypeId: vehicleTypeId }})
              .then(result=>{
                  d.vehicle = {
                    vehicleId: d.vehicleId,
                    vehicleTypeId: vehicleTypeId,
                    fixedCost: result.data[0].fixedCost,
                    variableCost: result.data[0].variableCost
                  }
                  hook.app.service('workers')
                    .find({ query: {assignedVehicleId: d.vehicleId}})
                    .then(result=>{
                        d.workers = [{
                          id:result.data[0].workerId,
                          name:result.data[0].name,
                          type:result.data[0].type
                        }];
                        delete d.vehicleId;
                  })
              })
          })
      resolve(hook)
      })
  })
}

Promise not working properly when I use inside map using javascript

3 Answers3