searching a nested javascript object, getting an array of ancestors

Question

I have a nested array like this:

array = [
    {
        "id": "67",
        "sub": [
            {
                "id": "663",
            },
            {
                "id": "435",
            }
        ]
    },
    {
        "id": "546",
        "sub": [
            {
                "id": "23",
                "sub": [
                 {
                     "id": "4",
                 }
             ]
            },
            {
                "id": "71"
            }
        ]
    }
]

I need to find 1 nested object by its id and get all its parents, producing an array of ids.

find.array("71")
=> ["546", "71"]

find.array("4")
=> ["546", "23", "4"]

What's the cleanest way to do this? Thanks.

Use recursion to walk down the tree and build the parent list each iteration. — user166390
– user166390, Commented Sep 11, 2011 at 21:25
What's your goal with this type of data-structure? It feels like you're going to have to loop through everything to get what you want. — rwilliams
– rwilliams, Commented Sep 11, 2011 at 21:25

Guffa · Accepted Answer · 2011-09-11 21:41:29Z

9

Recursively:

function find(array, id) {
  if (typeof array != 'undefined') {
    for (var i = 0; i < array.length; i++) {
      if (array[i].id == id) return [id];
      var a = find(array[i].sub, id);
      if (a != null) {
        a.unshift(array[i].id);
        return a;
      }
    }
  }
  return null;
}

Usage:

var result = find(array, 4);

Demo: http://jsfiddle.net/Guffa/VBJqf/

answered Sep 11, 2011 at 21:41

Guffa

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Comments

Paul Grime · Accepted Answer · 2011-09-11 21:47:12Z

1

Perhaps this - jsonselect.org.

EDIT: I've just had a play with JSONSelect and I don't think it's appropriate for your needs, as JSON does not have an intrinsic 'parent' property like xml.

It can find the object with the matching id, but you can't navigate upwards from that. E.g.

JSONSelect.match(':has(:root > .id:val("4"))', array)

returns me:

[Object { id="4"}]

which is good, it's just that I can't go anywhere from there!

edited Sep 11, 2011 at 21:47

answered Sep 11, 2011 at 21:25

Paul Grime

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2 Comments

Harry Over a year ago

Thanks, I really don't think this is the way to go, it's a rather large library for something simple

Paul Grime Over a year ago

Yes I understand and I agree! I just thought I'd edit my answer with the reasons why I didn't think it was appropriate in case folk wanted to see my reasoning :)

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