Json formation in typescript (Angular 7)

Question

I have a nested json as below.

{
card:[{
    id:1;
    details:[{id:1},{id:2}],
    sheet:{
        id:1
    }
},{
    id:2;
    details:[{id:3},{id:4}],
    sheet:{
        id:1
    }
}
]
}

---

I need to group details based on sheets as below.

{
sheet:{
    id:1,
    details:[{id:1},{id:2},{id:3},{id:4}]
}
 }

---

How could I achieve this in typescript?

Went through NPM-groupBy but I don't think it really solves my problem. Is there any other way to do this?

Answer 1

If I understand you correctly, this would be a good use case for the array reduce method, like:

const cards = [
  {
    id: 1,
    details: [
      {id:1},
      {id:2}
    ],
    sheet:{
      id:1
    }
  },
  {
    id:2,
    details: [
      {id:3},
      {id:4}
    ],
    sheet:{
      id:1
    }
  },
  {
    id:3,
    details: [
      {id:5},
      {id:6}
    ],
    sheet:{
      id:2
    }
  }
];

const sheets = cards.reduce( (sheets: Array<any>, card: any) => {
  const existingSheet = sheets.find(sheet => card.sheet.id === sheet.id);
    if (existingSheet) {
      existingSheet.details.concat(card.details);
    } else {
      sheets.push({id: card.sheet.id, details: card.details});
    }
    return sheets;
  }, []
);

console.log(sheets);