Convert array of objects with parent / child relationships to array of nested objects

Question

I have a problem transforming an array of objects to another array of nested objects. How can I transform table to look like transformedTable in the example code below?

Input data:

const table = [
  {id: 1, isMain: null, parentId: null, name:"john"},
  {id: 2, isMain: true, parentId: null, name:"sam"},
  {id: 3, isMain: null, parentId: 2, name:"samantha"},
  {id: 4, isMain: true, parentId: null, name:"kate"},
  {id: 5, isMain: true, parentId: 4, name:"jonathan"},
  {id: 6, isMain: null, parentId: 4, name:"walter"},
  {id: 7, isMain: null, parentId: 5, name:"clara"}
]

I want to transform the data above to something like this:

transformedTable = [{
    id: 1,
    isMain: null,
    parentId: null,
    name: "john"
  },
  {
    id: 2,
    isMain: true,
    parentId: null,
    name: "sam",
    kids: [{
      id: 3,
      isMain: null,
      parentId: 2,
      name: "samantha"
    }]
  },
  {
    id: 4,
    isMain: true,
    parentId: null,
    name: "kate",
    kids: [{
        id: 5,
        isMain: true,
        parentId: 4,
        name: "jonathan",
        kids: [{
          id: 7,
          isMain: null,
          parentId: 5,
          name: "clara"
        }]
      },
      {
        id: 6,
        isMain: null,
        parentId: 4,
        name: "walter"
      },
    ]
  },
]

Answer 1

You could nest a couple of loops to compare each object and add the "kids" property where needed. Then, filter the resulting array to leave just the ultimate parents (which contain all the nested children). See working snippet below:

 const table = [ {id: 1, isMain: null, parentId: null, name:"john"}, {id: 2, isMain: true, parentId: null, name:"sam"}, {id: 3, isMain: null, parentId: 2, name:"samantha"}, {id: 4, isMain: true, parentId: null, name:"kate"}, {id: 5, isMain: true, parentId: 4, name:"jonathan"}, {id: 6, isMain: null, parentId: 4, name:"walter"}, {id: 7, isMain: null, parentId: 5, name:"clara"} ]; const kid = (p, c) => { if (p.hasOwnProperty('kids')) { p.kids.push(c); } else { p.kids = [c]; } } for (let i = 0; i < table.length - 1; i++) { let a = table[i]; for (let j = i + 1; j < table.length; j++) { let b = table[j]; if (a.id === b.parentId) { kid(a, b); } else if (b.id === a.parentId) { kid(b, a); } } } let result = table.filter(x => !x.parentId); console.log(result); 

Answer 2

I had implemented same logic as Answer 1 with a little bit of changes code but I'm not getting an expected output. What might be the problem?