Map array to array of objects

Question

I have an changing array with selected items, where key is id:

[1, 2, 4, 6]

And array of objects:

items = [
  {
    id: 1,
    selected: false
  },
  {
    id: 2,
    selected: false
  },
  {
    id: 3,
    selected: false
  },
  {
    id: 4,
    selected: false
  },
  {
    id: 5,
    selected: true
  },
  {
    id: 6,
    selected: false
  }
]

How can I map selected array to items and change 'selected' to true and for other items change it to false?

There are a variety of ways you can accomplish this, however could you provide more details on your use case as there might be a better approach, then to simply iterating through all items and updating the value? For example you could change the items array to be a hashmap/object and to look similar to this: items: {1: {id: 1, selected: false}}, but it all depends — Vasil Dininski
– Vasil Dininski, Commented Dec 9, 2016 at 10:56

user663031 · Accepted Answer · 2016-12-09 11:07:30Z

3

items.forEach(item => item.selected = array.contains(item.id))

Simply loop through items, setting the selected property based on whether or not the id is contained in the array.

answered Dec 9, 2016 at 11:07

user663031

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Comments

RaR · Accepted Answer · 2016-12-09 11:05:33Z

2

var items = [
  {
    id: 1,
    selected: false
  },
  {
    id: 2,
    selected: false
  },
  {
    id: 3,
    selected: false
  },
  {
    id: 4,
    selected: false
  },
  {
    id: 5,
    selected: true
  },
  {
    id: 6,
    selected: false
  }
];
var array = [1, 2, 4, 6];

items.forEach(function(item) {
  item.selected = (array.indexOf(item.id) !== -1);
})

answered Dec 9, 2016 at 11:05

RaR

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Comments

Nina Scholz · Accepted Answer · 2016-12-09 11:49:18Z

1

You could use a Map and iterate the array and set all false, and then the selected to true.

var selected = [1, 2, 4, 6],
    items = [{ id: 1, selected: false }, { id: 2, selected: false }, { id: 3, selected: false }, { id: 4, selected: false }, { id: 5, selected: true }, { id: 6, selected: false }],
    map = new Map;

items.forEach(a => (map.set(a.id, a), a.selected = false));
selected.forEach(a => map.get(a).selected = true);

console.log(items);

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

A version with Set.

var selected = [1, 2, 4, 6],
    items = [{ id: 1, selected: false }, { id: 2, selected: false }, { id: 3, selected: false }, { id: 4, selected: false }, { id: 5, selected: true }, { id: 6, selected: false }],
    set = new Set(selected);

items.forEach(a => a.selected = set.has(a.id));

console.log(items);

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

edited Dec 9, 2016 at 11:49

answered Dec 9, 2016 at 10:58

Nina Scholz

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1 Comment

user663031 Over a year ago

It seems that selected changes, but items does not? In that case, the solution should build the map once from items, and then have a way to update items based on the new selected.

Maciej Kasprzak · Accepted Answer · 2016-12-09 10:55:58Z

0

var arr = [1,2,4,6];
var items = [
  {
    id: 1,
    selected: false
  },
  {
    id: 2,
    selected: false
  },
  {
    id: 3,
    selected: false
  },
  {
    id: 4,
    selected: false
  },
  {
    id: 5,
    selected: true
  },
  {
    id: 6,
    selected: false
  }
];

var notSelected = $.grep(items, function(e) { return arr.indexOf(e.id) == -1 }).map(function(e) { e.selected = false; return e;});
var selected = $.grep(items, function(e) { return arr.indexOf(e.id) != -1 }).map(function(e) { e.selected = true; return e;});

Result:

notSelected.concat(selected);

answered Dec 9, 2016 at 10:55

Maciej Kasprzak

9596 silver badges18 bronze badges

1 Comment

user663031 Over a year ago

usually better not to provide jQuery solutions unless requested.

Hikmat Sijapati · Accepted Answer · 2016-12-09 11:02:34Z

-1

Please Try it. I think it will works...

$new=array();
foreach($items as $item){
   if($item['selected']==false){
$new.=array_merge($item['id']);
    }
}
print_r($new);

And to change non selected items true.

foreach($items as $item){
if($item['selected']==false){
$item['selected']=true;
 }
}

edited Dec 9, 2016 at 11:02

answered Dec 9, 2016 at 10:55

Hikmat Sijapati

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1 Comment

user663031 Over a year ago

What language is this?

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