Filtering nested array of objects

Question

I have the following events array. For every event there is a hash as {organisation name: [{participant 1}, {participant 2}, {...}]}

"events": [
    {
        "Org A": [
            {
                "event_id": 1,
                "id": 432,
                "name": "John Doe",
                "role": null
            },
            {
                "event_id": 1,
                "id": 312,
                "name": "Jane Mow",
                "role": [
                  "speaker"
                ]
            }
        ],
    }
],

I would like to filter this events array to only contain participants whose role contains speaker. Also, when there are no speakers in the participant array, the respective organisation entry needs to be removed from the Hash (object).

To filter the array of objects, I tried using this:

_.each(events, function(event){
  _.filter(event, function(p) { 
   _.filter(p, function(d){ 
     return _.some(d.role, function(r){ 
      return r == "speaker"}) 
    }) 
  }) 
})

This however doesn't work.

d.role is an array and therefore r == speaker will never be true — Alex
– Alex, Commented Oct 22, 2015 at 9:45
filter does return a new array, but you're not doing anything with it. — Bergi
– Bergi, Commented Oct 22, 2015 at 9:49
_.some checks against each element of an array so why shouldn't d.role be an array? — supernova
– supernova, Commented Oct 22, 2015 at 9:50

Oleksandr T. · Accepted Answer · 2015-10-22 10:51:01Z

1

Try this

var data = {
    "events": [{
        "Org A": [{
            "event_id": 1,
            "id": 432,
            "name": "John Doe",
            "role": null
        }, {
            "event_id": 1,
            "id": 312,
            "name": "Jane Mow",
            "role": [
                "speaker"
            ]
        }],
        
        "Org B": [],
        "Org C": []
    }]
};

var SPEAKER = 'speaker';

var result = _.map(data.events, function (events) {
  return _.chain(events)
    .mapObject(function (value, key) {
      return _.filter(value, function (event) {
        return _.isArray(event.role) && _.indexOf(event.role, SPEAKER) >= 0; 
      });
    })
    .pick(function (value) {
      return value && value.length;
    })
    .value();
})

console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore.js"></script>

edited Oct 22, 2015 at 10:51

answered Oct 22, 2015 at 10:25

Oleksandr T.

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