Dynamically separate array to subarrays based on property with rx.js?

Question

I have the next input array. It can have different phases.

[
  {
  "id": 1,
  "phase": "Planning",
  },
  {
  "id": 2,
  "phase": "Planning",
  },
  {
  "id": 3,
  "phase": "Done",
  }
]

Based on phases I want to convert it to array with next format.

  [{title: 'Planning',
      datasets: {data: [/* 1st item will be here*/]},
               {data: [/* 2nd item will be here*/]}]},
      {title: 'Done',
          datasets: [{data: [/* 1st item will be here*/]}]
        }
      ];

How can I do this?

Thanks in advance

Do you really need to use RxJS for this?

martin
– martin

2018-07-11 14:08:16 +00:00
Commented Jul 11, 2018 at 14:08 — martin
– martin, Commented Jul 11, 2018 at 14:08

madjaoue · Accepted Answer · 2018-07-11 15:54:11Z

Not sure why you need rxjs for this, you can achieve it using only javascript. Here's a ES6 implementation :

let input = [
      {
      "id": 1,
      "phase": "Planning",
      },
      {
      "id": 2,
      "phase": "Planning",
      },
      {
      "id": 3,
      "phase": "Done",
      }
    ]
    
    let response = {};
    
    
    input.forEach(phaseObj=> {
    
      if(!!response[phaseObj["phase"]])
        response[phaseObj["phase"]].push({data: phaseObj})
      else
        response[phaseObj["phase"]] = [{data: phaseObj}]
    })
    
    response = Object.keys(response).map( key=> { return {title: key, datasets : response[key]}});
    console.log(response)

if you really insist on using rxjs, you can do something like :

let response = {};

Rx.Observable.from(input).map(phaseObj=> {
  if(!!response[phaseObj["phase"]])
    response[phaseObj["phase"]].push({data: phaseObj})
  else
    response[phaseObj["phase"]] = [{data: phaseObj}]
})
  .toArray()
  .subscribe( ()=> {
    response = response = Object.keys(response).map( key=> { return {title: key, datasets : response[key]}});
    console.log(response);
  })

dsych · Accepted Answer · 2018-07-12 20:13:11Z

0

You can use groupBy operator - it will group your data by object property

answered Jul 12, 2018 at 20:13

dsych

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2 Comments

Maks K Over a year ago

And how can I get next format? {'title': 'Planning', 'datasets': {data: [/* 1st item will be here*/]},

dsych Over a year ago

You can map as you want - ...groupBy(data).pipe(toArray()),map( mapFnToDesiredFormat ).... So, for example you have [{title: 'B2', name: "Sue"},{title: 'B2', name: "Frank"}] as first group. Map fn is (v) => ({title: v[0].title, datasets:{data:[v[0]]}}).

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