How can I get a find an object in an array by a property?

Question

I have the following array returned from a php script.

$data =  [
    {
        "id": "1",
        "created_at": "2015-01-02 15:17:29",
        "updated_at": "2015-01-02 15:17:29",
        "name": "Minecraft",
        "description": "",
        "location": "ideaLab",
        "cost": "20.00",
        "min_age": "7",
        "max_age": null,
        "start_date": "2014-11-06",
        "end_date": "2014-12-11",
        "start_time": "16:30:00",
        "end_time": "17:30:00",
        "registration_start_date": "2014-10-28",
        "registration_end_date": "0000-00-00",
        "program_id": "1",
        "max_attendees": "12"
    },
    {
        "id": "2",
        "created_at": "2015-01-02 15:17:29",
        "updated_at": "2015-01-02 15:17:29",
        "name": "Mini Makers",
        "description": "",
        "location": "ideaLab",
        "cost": "18.00",
        "min_age": "9",
        "max_age": "7",
        "start_date": "2014-11-04",
        "end_date": "2014-12-09",
        "start_time": "16:30:00",
        "end_time": "17:30:00",
        "registration_start_date": "2014-10-28",
        "registration_end_date": "0000-00-00",
        "program_id": "2",
        "max_attendees": "20"
    }
];

How do I select the object by id? something like the SQL equivalent of $obj = select * where id=$id if that makes sense.

Traverse the array? Btw is is only JSON as long as it is a string. After you parse it is a mere JavaScript object. — Sirko, Jan 09 '15 at 15:58
just put them all into a list iterate through them until you find it or use map. — Lucas, Jan 09 '15 at 15:59
You can use [JSONPath](http://goessner.net/articles/JsonPath/) as a more elegant solution — Lukas Hajdu, Jan 09 '15 at 16:02

Fabrizio Calderan · Accepted Answer · 2015-01-09T16:20:00.793

5

You could use a generic function that accepts the id as argument and return the object (if the id exists)

function getObjectById(id) {
   for (var i = 0; i < $data.length; i++) {
      if ($data[i]['id'] === id) {
         return $data[i];
      }
   }
   return {};
}

but if your output it's exactly what you posted and you have not missing id in the sequence you could just reduce the body of the function to

return (id > 0 && id <= $data.length) ? $data[id - 1] : {}

(in this scenario I assume you pass an integer number as id)

edited Jan 09 '15 at 16:20

answered Jan 09 '15 at 15:59

Fabrizio Calderan

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1

The most straight forward answer, but I would probably return `null` if not found – Rhumborl Jan 09 '15 at 16:01
1

I would do == instead of === because id is a string and may be used as a number ? – Hacketo Jan 09 '15 at 16:02
1

@Hacketo I just prefer by default strict comparison. as long as the values are all strings and you pass a string as parameter then `===` is fine – Fabrizio Calderan Jan 09 '15 at 16:05
Is this PHP or JavaScript? – Praveen Kumar Purushothaman Jan 09 '15 at 16:07
it's vanillaJS @PraveenKumar – Fabrizio Calderan Jan 09 '15 at 16:09
@FabrizioCalderan Your use of `$` in front of the variable name was the confusion. Thanks for the clarification. – Praveen Kumar Purushothaman Jan 09 '15 at 16:10
Thanks my output is as posted. I was not aware that it was missing a id in the sequence. I will see if there is a way to add that to the php output. I used Laravel framework .toJson() function. I would have to ensure that the id of the object will always align to the id inside the object though which I would rather not do. – Phil Jan 09 '15 at 17:19
@Hacketo thanks == is better for me, it is stored as a number in my database but from my research some databases might output as string so I think it best to be as type agnostic as possible here. – Phil Jan 09 '15 at 18:25

score 3 · Answer 2 · edited Jan 09 '15 at 16:06

3

You can use a small script like this:

function findJSONById(needle, jsonString)
{
  var finalJSON = {};
  $.each(JSON.parseJSON(jsonString), function (key, value) {
    if (value["id"] == needle)
    {
      finalJSON = value;
      return false; // break the loop
    }
  });
  return finalJSON;
}

edited Jan 09 '15 at 16:06

Rhumborl

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answered Jan 09 '15 at 16:00

Praveen Kumar Purushothaman

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2

The `return` does not return from the outer function, though. – Sirko Jan 09 '15 at 16:01
1

I furthermore added a few keywords. – Sirko Jan 09 '15 at 16:03
Shit! How did I even miss that? `:O` Okay I am drowsy, I need to sleep! `:P` – Praveen Kumar Purushothaman Jan 09 '15 at 16:06

score 1 · Answer 3 · answered Jan 09 '15 at 16:07

1

If you are using jQuery there is a nice function: $.grep

It filters input array based on filter function.

var objectWithId2 = $.grep(data, function (obj) { 
    return obj.id == 2; 
})[0];

answered Jan 09 '15 at 16:07

Rev

57
4

score 0 · Answer 4 · answered Jan 09 '15 at 16:25

0

Try

var filtered = function(data, id) {
  return data.filter(function(items, i) {
    return items.id === id
  })
};

console.log(filtered("1"));

answered Jan 09 '15 at 16:25

guest271314

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rm-vanda · Answer 5 · 2015-01-09T17:37:14.973

-2

You would use :

$data[0].id

So, to get the object by it's id:

$data[$id+1]  //so long as their position in the array is not shuffled.

Or, so long as you are using jQuery, something like this should be helpful:

$.each(data, function(index) {  console.log(data[i].id); });

edited Jan 09 '15 at 17:37

answered Jan 09 '15 at 15:59

rm-vanda

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3

This gets the id of each object. OP wants to find the entire object by its id. – Rory McCrossan Jan 09 '15 at 16:00
1

Should be $id - 1 i guess. – Hacketo Jan 09 '15 at 16:20

How can I get a find an object in an array by a property?

5 Answers5