Create tree structure from javascript array of object

Question

I have an array of objects like this..

var obj_1 = {id:1, title:"Title 1", unitId:0, line: 0};
var obj_2 = {id:2, title:"Title 1.1", unitId:1, line: 0};
var obj_3 = {id:3, title:"Title 1.2", unitId:1, line: 1};
var obj_4 = {id:4, title:"Title 1.1.1", unitId:0, line: 1};
var obj_5 = {id:5, title:"Title 2", unitId:0, line: 1};

var obj_list = [obj_1,obj_2,obj_3,obj_4,obj_5];

I want to convert the json to tree structure, my result structure like this

Unit 0: {
  Line 0: {
     children: {
        {id:1, title:"Title 1", unitId:0, line: 0}
     }
  },
  Line 1: {
     children: {
        {id:4, title:"Title 1.1.1", unitId:0, line: 1},
        {id:5, title:"Title 2", unitId:0, line: 1}
     }
  }
}
Unit 1: {
  Line 0: {
     children: {
        {id:2, title:"Title 1.1", unitId:1, line: 0}
     }
  },
  Line 1: {
     children: {
        {id:2, title:"Title 1.2", unitId:1, line: 2}
     }
  }
}

If anyone know how to do, please answer. Thanks in advance

I have tried using foreach and array reduce but its didn't work. — Raj
– Raj, Commented Oct 15, 2019 at 7:34

Nina Scholz · Accepted Answer · 2019-10-15 07:53:48Z

2

You could take an array of the wanted keys for nesting and build new object with this keys and push at the end the object to the children property.

var data = [{ id: 1, title: "Title 1", unitId: 0, line: 0 }, { id: 2, title: "Title 1.1", unitId: 1, line: 0 }, { id: 3, title: "Title 1.2", unitId: 1, line: 1 }, { id: 4, title: "Title 1.1.1", unitId: 0, line: 1 }, { id: 5, title: "Title 2", unitId: 0, line: 1 }],
    keys = [['unitId', 'Unit'], ['line', 'Line']],
    result = data.reduce((r, o) => {
        var target = keys.reduce((q, [k, t]) => {
                var key = [t, o[k]].join(' ');
                return q[key] = q[key] || {};
            }, r);
        (target.children = target.children || []).push(o);
        return r;
    }, {});

console.log(result);

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The same with letters for a special key.

var data = [{ id: 1, title: "Title 1", unitId: 0, line: 0 }, { id: 2, title: "Title 1.1", unitId: 1, line: 0 }, { id: 3, title: "Title 1.2", unitId: 1, line: 1 }, { id: 4, title: "Title 1.1.1", unitId: 0, line: 1 }, { id: 5, title: "Title 2", unitId: 0, line: 1 }],
    keys = [['unitId', 'Unit'], ['line', 'Line', v => (10 + v).toString(36).toUpperCase()]],
    result = data.reduce((r, o) => {
        var target = keys.reduce((q, [k, t, fn = v => v]) => {
                var key = [t, fn(o[k])].join(' ');
                return q[key] = q[key] || {};
            }, r);
        (target.children = target.children || []).push(o);
        return r;
    }, {});

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

edited Oct 15, 2019 at 7:53

answered Oct 15, 2019 at 7:41

Nina Scholz

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5 Comments

Raj Over a year ago

If I want Line 0 to Line A and Line 1 to Line B...then what will I do ?

Nina Scholz Over a year ago

only for lines?

Raj Over a year ago

Now I want to push Line o and Line 1 into Unit 0.children..please reply me

Nina Scholz Over a year ago

please ask a new question.

Raj Over a year ago

stackoverflow.com/questions/58391221/…

zendka · Accepted Answer · 2019-10-15 07:48:04Z

0

First: get the structure you desire:

const structure = [];
for (obj of obj_list) {
  if (!structure[obj.unitId]) {
    structure[obj.unitId] = [];
  }
  if (!structure[obj.unitId][obj.line]) {
    structure[obj.unitId][obj.line] = [];
  }
  structure[obj.unitId][obj.line].push(obj);
}

Next: output this in the format you desire. You can probably handle this last step.

answered Oct 15, 2019 at 7:48

zendka

1,38713 silver badges11 bronze badges

Comments

Mauro Insacco · Accepted Answer · 2019-10-15 07:51:44Z

There's probably a cleaner way, just wanted to give a quick answer

const obj_1 = { id: 1, title: 'Title 1', unitId: 0, line: 0 };
const obj_2 = { id: 2, title: 'Title 1.1', unitId: 1, line: 0 };
const obj_3 = { id: 3, title: 'Title 1.2', unitId: 1, line: 1 };
const obj_4 = { id: 4, title: 'Title 1.1.1', unitId: 0, line: 1 };
const obj_5 = { id: 5, title: 'Title 2', unitId: 0, line: 1 };

const obj_list = [obj_1, obj_2, obj_3, obj_4, obj_5];

newJson = {};
obj_list.forEach(el => {
    newJson[`unit${el.unitId}`] ? null : (newJson[`unit${el.unitId}`] = {});
    newJson[`unit${el.unitId}`][`line${el.line}`]
        ? null
        : (newJson[`unit${el.unitId}`][`line${el.line}`] = {});
    newJson[`unit${el.unitId}`][`line${el.line}`].children
        ? null
        : (newJson[`unit${el.unitId}`][`line${el.line}`].children = []);

    newJson[`unit${el.unitId}`][`line${el.line}`].children.push(el);
});

console.log(newJson);

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