Best way for nest child objects from objects array with Javascript

Question

Hi masters i need to find the best way to convert this:

 [
  { "id": 1, "animal": "cat", "age": 6, "name": "loky" },
  { "id": 2, "animal": "cat", "age": 3, "name": "michu", "parent": 1 },
  { "id": 3, "animal": "cat", "age": 2, "name": "boots", "parent": 1 },
  { "id": 4, "animal": "dog", "age": 9, "name": "bones" },
  { "id": 5, "animal": "dog", "age": 6, "name": "chok", "parent": 4 },
  { "id": 6, "animal": "dog", "age": 6, "name": "cofee","parent": 4 }
]

to this:

 [
  { "id": 1,
    "animal": "cat",
    "age": 6,
    "name": "loky",
    "childs":[ { "id": 2, "animal": "cat", "age": 3, "name": "michu", "parent": 1 },
               { "id": 3, "animal": "cat", "age": 2, "name": "boots", "parent": 1 }] 
  }
  ,
  { "id": 4,
    "animal": "dog",
    "age": 9,
    "name": "bones",
    "childs":[{ "id": 5, "animal": "dog", "age": 6, "name": "chok", "parent": 4 },
              { "id": 6, "animal": "dog", "age": 6, "name": "cofee", "parent": 4 }]
  }
 ]

note that the "parent" key must be used to nest "childs" ,i create my way but with several functions is horrible ,i think there may be a more efficient way.

Thanks in advance sorry for my english

Get familiar with how to access and process objects, arrays, or JSON, how to access properties, and use the static and instance methods of Object and Array. Without knowing what “horrible” approach you took, how can we know which approaches constitute an adequate answer to this question? — Sebastian Simon
– Sebastian Simon, Commented Nov 17, 2022 at 13:01
Does Convert array of objects with parent ids to a nested tree structure help? — Sebastian Simon
– Sebastian Simon, Commented Nov 17, 2022 at 13:04

Shawn · Accepted Answer · 2022-11-17 13:32:45Z

1

const rows = [
  { id: 1, animal: 'cat', age: 6, name: 'loky' },
  { id: 2, animal: 'cat', age: 3, name: 'michu', parent: 1 },
  { id: 3, animal: 'cat', age: 2, name: 'boots', parent: 1 },
  { id: 4, animal: 'dog', age: 9, name: 'bones' },
  { id: 5, animal: 'dog', age: 6, name: 'chok', parent: 4 },
  { id: 6, animal: 'dog', age: 6, name: 'cofee', parent: 4 },
];

function map(rows) {
  const categories = Array.from(new Set(rows.map((row) => row.animal)));
  return categories.map((c) => {
    const parent = rows.find((row) => row.animal === c);
    parent.childs = rows
      .filter((r) => r.id !== parent.id && r.animal === c)
      .map((r) => ({ ...r, parent: parent.id }));
    return parent;
  });
}

console.log(map(row));

Simply create a mapper function to do.

answered Nov 17, 2022 at 13:32

Shawn

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4 Comments

Cristian Garate Over a year ago

Thanks a lot this helpme so much ,with your tips a mede other function working fine, but maybe can make some better? <br>

function nester(arr){   parents = rows.filter((row) => row.parent? '' : row.child=[])   parents.forEach(function(e){   arr.forEach((r)=> r.parent == e.id? e.child.push(r) :  '') })   parents = parents.filter(elem => elem.child.length < 1? delete elem.child : elem)   return parents    }

Shawn Over a year ago

@CristianGarate Sorry I didn't get what you expected for this code. Explain more please

Cristian Garate Over a year ago

i do a pen link

Shawn Over a year ago

@CristianGarate, we can optimize, which would make the code uglier. But on the other hand, we can gain the time complexity. You know there are always pros and cons that exist

Shawn · Accepted Answer · 2022-11-17 21:18:56Z

0

Maybe?

const rows = [
  { id: 1, animal: 'cat', age: 6, name: 'loky' },
  { id: 2, animal: 'cat', age: 3, name: 'michu', parent: 1 },
  { id: 3, animal: 'cat', age: 2, name: 'boots', parent: 1 },
  { id: 4, animal: 'dog', age: 9, name: 'bones' },
  { id: 5, animal: 'dog', age: 6, name: 'chok', parent: 4 },
  { id: 6, animal: 'dog', age: 6, name: 'cofee', parent: 4 },
];

function nester(arr) {
  const parents = rows.filter((r) => !r.parent);
  const children = rows.filter((r) => r.parent);
  return parents.map((p) => {
    return {
      ...p,
      children: children.filter((c) => c.parent === p.id),
    };
  });
}
console.log(nester(rows));

answered Nov 17, 2022 at 21:18

Shawn

1317 bronze badges

1 Comment

Cristian Garate Over a year ago

Thanks but supose i put another object like : { "id": 0, "animal": "cat", "age": 10, "name": "oldy" } then with your function add a "children" empty property

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