Empty return of variable

Question

I have this code:

    var results_ = ger.recommendations_for_person('movies', query.name, {actions: {likes: 1}});
  var recommendations = results_.recommendations;

  return recommendations;

ger.recommendations_for_person('movies', query.name, {actions: {likes: 1}}); is meant to return something as such.

 {
      "recommendations": [
        {
          "thing": "spiderman",
          "weight": 1.6666666666666667,
          "last_actioned_at": "2019-05-17T23:06:54+01:00",
          "last_expires_at": "2020-06-06T01:00:00+01:00",
          "people": [
            "bob",
            "alice"
          ]
        },
        {
          "thing": "xmen",
          "weight": 1.6666666666666667,
          "last_actioned_at": "2019-05-17T23:06:54+01:00",
          "last_expires_at": "2020-06-06T01:00:00+01:00",
          "people": [
            "alice",
            "bob"
          ]


        },
        {
          "thing": "barbie",
          "weight": 1,
          "last_actioned_at": "2019-05-17T23:06:54+01:00",
          "last_expires_at": "2020-06-06T01:00:00+01:00",
          "people": [
            "alice"
          ]
        },
        {
          "thing": "avengers",
          "weight": 0.6666666666666667,
          "last_actioned_at": "2019-05-17T23:06:54+01:00",
          "last_expires_at": "2020-06-06T01:00:00+01:00",
          "people": [
            "bob"
          ]
        }
      ],
      "neighbourhood": {
        "bob": 0.6666666666666667,
        "alice": 1
      },
      "confidence": 0.002462038997842016
    }

And it works perfectly if I just return results. But why can't I return recommendations.It returns a blank screen.

My question is different from How do I return the response from an asynchronous call? because for one thing ,I am using nodejs not ajax.It is meant to be synchronous. This is the full code for `

recc_.js:

var http = require('http'),
    url = require('url');
// require the ger objects
http.createServer(function (request, response) {
  var query = url.parse(request.url,true).query;

var g = require('../ger')

// Create an Event Store Manager (ESM) that stores events and provides functions to query them
var esm = new g.MemESM()

// Initialize GER with the esm
var ger = new g.GER(esm);

ger.initialize_namespace('movies')
.then( function() {
  return ger.events([


 ////RECCOMMENDATION LISTS



    { 
      namespace: 'movies', 
      person: 'bob', 
      action: 'likes', 
      thing: 'xmen',
      expires_at: '2020-06-06' 
    },
    { 
      namespace: 'movies', 
      person: 'bob', 
      action: 'likes', 
      thing: 'avengers',
      expires_at: '2020-06-06' 
    },

    { 
      namespace: 'movies', 
      person: 'bob', 
      action: 'likes', 
      thing: 'spiderman',
      expires_at: '2020-06-06' 
    },

    { 
      namespace: 'movies', 
      person: 'alice', 
      action: 'likes', 
      thing: 'xmen',
      expires_at: '2020-06-06' 
    },
    { 
      namespace: 'movies', 
      person: 'alice', 
      action: 'likes', 
      thing: 'spiderman',
      expires_at: '2020-06-06' 
    },
    { 
      namespace: 'movies', 
      person: 'alice', 
      action: 'likes', 
      thing: 'barbie',
      expires_at: '2020-06-06' 
    },

 ////RECCOMMENDATION LISTS





  ])
})
.then( function() {
  // What things might alice like?



  var results_ = ger.recommendations_for_person('movies', query.name, {actions: {likes: 1}});
  var recommendations = results_.recommendations;
  //var results = results_[reccomendations.map(({ thing }) => thing)];

  return recommendations;


})
.then( function(recommendations) {
  response.end(JSON.stringify(recommendations,null,2))
  response.end("\nRecommendations For 'alice'")
})

}).listen(8080);


console.log(' server running ok http://127.0.0.1:8080/');

The implementation for var results_ = ger.recommendations_for_person('movies', query.name, {actions: {likes: 1}}) is :

recommendations_for_person: (namespace, person, configuration = {}) ->
    configuration = @default_configuration(configuration)
    actions = configuration.actions

    #first a check or two
    @find_events(namespace, actions: Object.keys(actions), person: person, current_datetime: configuration.current_datetime, size: 100)
    .then( (events) =>

      return {recommendations: [], confidence: 0} if events.length < configuration.minimum_history_required

      return @generate_recommendations_for_person(namespace, person, actions, events.length, configuration)
    )

Possible duplicate of [How do I return the response from an asynchronous call?](https://stackoverflow.com/questions/14220321/how-do-i-return-the-response-from-an-asynchronous-call) — connexo, May 18 '19 at 00:09
I suspect this is the typical async issue, but please show a [mcve]. The code you posted here is pretty incomplete. — Carcigenicate, May 18 '19 at 00:10
@connexo That is the main part but if u like me 2 show u more I can] — Turbo, May 18 '19 at 00:11
Because you misspelled it: `reccomendations` vs `recommendations` there is no `reccomendations` property on your object — Patrick Evans, May 18 '19 at 00:12
_"nodejs not ajax.It is meant to be synchronous."_ nodejs has async methods, network requests and file operation methods that dont have Sync at the end for example are async. Just because that post talks about ajax the principal is still the same you dont wait for .recommendations_for_person() to finish before trying to access the data — Patrick Evans, May 18 '19 at 00:18

score 1 · Answer 1 · answered May 18 '19 at 00:35

I GOT IT!!!

I just had to do:

.then( function() {
  // What things might alice like?



   return results_ = ger.recommendations_for_person('movies', query.name, {actions: {likes: 1}});

})
.then(function(results_) {
  var recommendations = results_.recommendations;
  //var results = results_[reccomendations.m ap(({ thing }) => thing)];

  return recommendations;

  })
.then( function(recommendations) {
  response.end(JSON.stringify(recommendations,null,2))
  response.end("\nRecommendations For 'alice'")
})

ie using Promises

Empty return of variable

1 Answers1