CODEWITHSUNDEEP
javascriptlodash
David Draper
David Draper

Reputation: 79

lodash unable to flatten array

I am trying to unnest an array currently using this code:

var mapped = _.flatMap(payload, ({GroupId,Learners}) =>
    _.map(Learners, LearnerId => ({GroupId:GroupId,Learner:LearnerId}))
);

however the value return still produces and array: e.g

{"GroupId":1246574,"Learner":{"Forename":"George","Surname":Bob",,"StartDate":"2020-09-01","EndDate":"2021-08-27"}}

How can I adapt the script above to only return the GroupId and the Surname?

Example of the payload is here:

var payload = 
{
    "GroupId": 1208864,
    "Code": "Ext-StuOth",
    "GroupType": "AcademicHouseGroup",
    "Learners": [
        {
            "LearnerId": 245218,
            "LearnerCode": "2009-0017",
            "Forename": "Sanelisiwe",
            "Surname": "Nazi-Angileh",
            "LearnerGroupLearnerId": 14719301,
            "StartDate": "2017-03-09",
            "EndDate": null
        },
        {
            "LearnerId": 246638,
            "LearnerCode": "2013-0076",
            "Forename": "Randal",
            "Surname": "Bodziarczyk",
            "LearnerGroupLearnerId": 14650361,
            "StartDate": "2017-02-20",
            "EndDate": null
        },
        {
            "LearnerId": 245253,
            "LearnerCode": "109056",
            "Forename": "Wafah",
            "Surname": "Dadisman",
            "LearnerGroupLearnerId": 14650360,
            "StartDate": "2017-02-20",
            "EndDate": null
        }
},{
            "GroupId": 1226419,
            "Code": "U6-JD",
            "GroupType": "RegistrationGroup",
            "Learners": [
                {
                    "LearnerId": 245507,
                    "LearnerCode": "110015",
                    "Forename": "Nahomy",
                    "Surname": "Osburn",
                    "LearnerGroupLearnerId": 14918706,
                    "StartDate": "2017-09-07",
                    "EndDate": "2018-07-31"
                },
                {
                    "LearnerId": 245994,
                    "LearnerCode": "111624",
                    "Forename": "Sherhona",
                    "Surname": "Dobritoiu",
                    "LearnerGroupLearnerId": 14707593,
                    "StartDate": "2017-08-01",
                    "EndDate": "2018-07-31"
                }
}

Upvotes: 0

Views: 108

Answers (2)

ziganotschka
ziganotschka

Reputation: 26806

It is not an array, it is a JSON object (that contains arrays)

You can access access the elements as following:

  console.log(payload.GroupId);
  var learners = payload.Learners;
  learners.forEach(function(learner){    
  console.log(learner.Surname);

Upvotes: 0

Madhu Magar
Madhu Magar

Reputation: 445

var result = _.flatMap(payload, ({GroupId, Learners}) => {
    return _.map(Learners, learner => ({GroupId, LearnerId: learner.LearnerId}))
})

Upvotes: 1

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