Update Multiple Objects in Nested Arrays

Question

I have an array of multi dimensional objects:

var arr = [
  {
    id: '10c',
    name: 'item 1'
    children: [
      {id: '11v', name: 'Item 1 child 1'},
      {id: '12c', name: 'Item 1 child 2'}
    ]
  },
  {
    id: '13v',
    name: 'item 2'
    children: [
      {id: '26e', name: 'Item 2 child 1'},
      {id: '7a', name: 'Item 2 child 2'}
    ]
  }
]

and another object of data:

var array = [
  {id: '12c', name: 'New name 1'},
  {id: '26e', name: 'New name 2'},
  {id: '11v', name: 'New name 3'},
];

If I want to update the name value of the respective objects in arr, based on the id value in array, how would be the best way of doing that?

arr might be more than 2 levels deep, so I would like to be able to do it without having to nest multiple forEach

github.com/gaearon/normalizr is a library made for your use case b y normalising nested JSON. — krs
– krs, Commented Feb 11, 2016 at 13:36

karaxuna · Accepted Answer · 2016-02-11 13:38:30Z

3

Try this:

function update(items, id, name) {
    var item;
    for (var i = 0; i < items.length; i++) {
        item = items[i];
        if (item.id === id) {
            item.name = name;
            return;
        }
        if (item.children) {
             update(item.children, id, name);
        }
    }
}

Then:

update(arr, '11v', 'test');

Updating by array:

array.forEach(function (item) {
    update(arr, item.id, item.name);
});

edited Feb 11, 2016 at 13:38

answered Feb 11, 2016 at 13:33

karaxuna

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Comments

Dan Prince · Accepted Answer · 2016-02-11 13:32:07Z

Use a recursive solution and make use of the inherent mutability of Javascript.

First build up a flat map representation of all the objects.

function createObjectMap(array) {
  var map = {};

  array.forEach(function(obj) {
    map[obj.id] = obj;

    if(obj.children) {
      Object.assign(map, createObjectMap(obj.children));
    }
  });

  return map;
}

Now you've got a map of id -> object you can use. They reference the same mutable objects, so you can mutate them in place and know that they'll also update in the original data structure.

function update(map, updates) {
  updates.forEach(function(update) {
    map[update.id].name = update.name;
  });
}

This conversion to O(1) lookup time means you don't have to write any searching logic.

Pankaj Parkar · Accepted Answer · 2016-02-11 13:38:20Z

0

You could use angular $filter to do the same

//to get element
function getFiltered(collection, obj){
   var filtered = $filter('filter')(collection, obj, true);
   if(filtered[0])
     return filtered[0]
   if(collection.children)
     return getFiltered(collection.children, obj, true);
}

angular.forEach(array, function(element){
    var filtered = getFiltered(array, { id: element.id })
    if(filtered[0]) filtered.name = element.name;
})

edited Feb 11, 2016 at 13:38

answered Feb 11, 2016 at 13:32

Pankaj Parkar

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