Normalize missing value inside an array of objects with nodejs

Question

I have this data scenario:

var data = [
 {
  'name': 'social-button',
  'group': null
 }, {
  'name': 'social-button',
  'group': null
 }, {
  'name': 'social-button',
  'group': 'buttons'
 }, {
  'name': 'social-button',
  'group': null
 }, {
  'name': 'icon',
  'group': 'icons'
 }, {
  'name': 'other',
  'group': null
 }, {
  'name': 'icon',
  'group': null
 }
];

I would like to normalize this data to this:

var data = [
 {
  'name': 'social-button',
  'group': 'buttons'
 }, {
  'name': 'social-button',
  'group': 'buttons'
 }, {
  'name': 'social-button',
  'group': 'buttons'
 }, {
  'name': 'social-button',
  'group': 'buttons'
 }, {
  'name': 'icon',
  'group': 'icons'
 }, {
  'name': 'other',
  'group': null
 }, {
  'name': 'icon',
  'group': 'icons'
 }
];

So basically, I would like to ensure every element which have the same name should also have the same group, if just one of the same have one.

Does exists some node module could help in this?

Or maybe, does exist some smart way to do that?

Nina Scholz · Accepted Answer · 2017-01-06 14:06:27Z

3

You could use two loops, one to collect values in a hash table and one to assign.

var data = [{ 'name': 'social-button', 'group': null }, { 'name': 'social-button', 'group': null }, { 'name': 'social-button', 'group': 'buttons' }, {  'name': 'social-button', 'group': null }, { 'name': 'icon', 'group': 'icons' }, { 'name': 'other', 'group': null }, { 'name': 'icon', 'group': null }],
    hash = Object.create(null);

data.forEach(function (a) {
    hash[a.name] = hash[a.name] || a.group;
});

data.forEach(function (a) {
    a.group = a.group || hash[a.name];
});

console.log(data);

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

edited Jan 6, 2017 at 14:06

answered Jan 6, 2017 at 13:51

Nina Scholz

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3 Comments

OrangeDog Over a year ago

You type faster than me :) Though I was going to use map to avoid changing the original.

Nina Scholz Over a year ago

it looks like a seach for an in-situ solution.

vitto Over a year ago

It worked flawlessly, also didn't changed the order of the items, and finally, it's very easy to read, thank you very much

Nenad Vracar · Accepted Answer · 2017-01-06 13:54:03Z

You could first sort() your array so objects with group values come first and then use map() to create new array. You can use Object.assign() to clone objects so you can don't change your original data.

var data = [{"name":"social-button","group":null},{"name":"social-button","group":null},{"name":"social-button","group":"buttons"},{"name":"social-button","group":null},{"name":"icon","group":"icons"},{"name":"other","group":null},{"name":"icon","group":null}]

var result = data.sort((a, b) => b.group != null).map(function(o) {
  if (!this[o.name]) {
    this[o.name] = o.group
    return o
  } else {
    var obj = Object.assign({}, o);
    obj.group = this[o.name];
    return obj
  }
}, {})

console.log(result)

kukkuz · Accepted Answer · 2017-01-06 14:06:57Z

0

You can do that in one pass by using Array.prototype.reduce and a hash table - see demo below:

var data=[{'name':'social-button','group':null},{'name':'social-button','group':null},{'name':'social-button','group':'buttons'},{'name':'social-button','group':null},{'name':'icon','group':'icons'},{'name':'other','group':null},{'name':'icon','group':null}];

var result = data.reduce((function(hash){
  return function(p,c) {
    hash[c.name] = hash[c.name] || c;
    if(c.group)
      hash[c.name].group = c.group;
    p.push(hash[c.name]);
    return p;
  };
})(Object.create(null)), []);

console.log(JSON.stringify(result));

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answered Jan 6, 2017 at 14:06

kukkuz

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