PHP: Convert Object to Associative Array with Object Property as Key

Question

In PHP, I'd like to convert an array of objects like the following to a PHP array, using one of the properties as the associative array keys.

[
  { "id": 2, "name": "Suzy" },
  { "id": 3, "name": "Joe" },
  { "id": 4, "name": "Sara" }
]

like this...

[
  2 => "Suzy",
  3 => "Joe",
  4 => "Sara"
]

I can't use array_map because you can't set the keys from my understanding, but I'm wondering if there's a one-liner way to do it without a foreach loop.

To be clear, I want to maintain the keys in the output array, not puts the original keys inside the new array values like they do here: PHP's array_map including keys

Possible duplicate of [PHP's array\_map including keys](https://stackoverflow.com/questions/13036160/phps-array-map-including-keys) — marekful, Aug 01 '18 at 18:13
@vivek_23 I just wanted a one liner if possible. All I could come up with was 4 lines. — dmgig, Aug 01 '18 at 18:23
@marekful I don't see how it's the same. They aren't maintaining the keys in the output array, their desired output puts the original keys inside the new array values. — dmgig, Aug 01 '18 at 18:29
I don't really care, I guess I was hoping to find there was some variation of array_map or some PHP function that would allow it to be done. — dmgig, Aug 01 '18 at 18:32
@dgig, I meant to indicate that that post deals with how to work around array_map's inability do handle keys. The plenty of answers there combined with a little imagination should kick you off on some good path. — marekful, Aug 01 '18 at 19:25

score 4 · Accepted Answer · answered Aug 01 '18 at 18:18

4

It appears by "object" you mean a JSON object. Given that, you can use array_column() to pull out a single column from each row, and then array_combine() to use one column for the keys and another for the values:

$json = '[
    { "id": 2, "name": "Suzy" },
    { "id": 3, "name": "Joe" },
    { "id": 4, "name": "Sara" }
]';
$array = json_decode($json, true);
$out = array_combine(array_column($array, 'id'), array_column($array, 'name'));
print_r($out);

Yields:

Array
(
    [2] => Suzy
    [3] => Joe
    [4] => Sara
)

answered Aug 01 '18 at 18:18

Alex Howansky

50,515
8
78
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This is great. It isn't json, just an array of objects. I didn't know another way to show it. But this looks good to me. Thank you. – dmgig Aug 01 '18 at 18:24
1

Note this should work as is on objects if they implement ArrayAccess. – Alex Howansky Aug 01 '18 at 18:25

score 0 · Answer 2 · answered Aug 01 '18 at 18:34

2 liners and has a foreach though.

<?php

$json = '[
  { "id": 2, "name": "Suzy" },
  { "id": 3, "name": "Joe" },
  { "id": 4, "name": "Sara" }
]';

$new_array = [];
foreach(json_decode($json,true) as $each_object) $new_array[$each_object['id']] = $each_object['name'];

print_r($new_array);

score 0 · Answer 3 · answered Mar 16 '20 at 21:32

0

$json = '[
    { "id": 2, "name": "Suzy" },
    { "id": 3, "name": "Joe" },
    { "id": 4, "name": "Sara" }
]';
$array = json_decode($json, true);
$result = array_column($array, 'name', 'id');

answered Mar 16 '20 at 21:32

Rafał Rudowski

1
2

PHP: Convert Object to Associative Array with Object Property as Key

3 Answers3