Convert an object to a array in PHP

Question

I received this from an Ajax call in my PHP page:

[{"id":8},{"id":10},{"id":11},{"id":12}]

How can I parse it in order to have something like this :

array(8, 10, 11, 12)

Thanks.

Answer 1

You can use array_map for that:

<?php
$array = json_decode( '[{"id":8},{"id":10},{"id":11},{"id":12}]' );
function getId($n) {
    return($n->id);
}
$mapped = array_map("getId", $array);
var_dump($mapped);
?>

http://sandbox.onlinephpfunctions.com/code/e74f6252bcf9b321115af8626ca7ebc192414730

Answer 2

First of all you need to decode your json to an array, then iterate it and grab your values. Something like this.

<?php

$json = '[{"id":8},{"id":10},{"id":11},{"id":12}]';

$array = json_decode($json, true);

$result = array_map(static function ($el) {
    return $el['id'];
}, $array);

print_r($result);

Answer 3

First, let's look what you have here.

[{"id":8},{"id":10},{"id":11},{"id":12}] is the json representation of an array that contains objects. We can use the function json_decode to get the data out of such a json representation. var_dump(json_decode($json)); would look like this:

array(4) {
  [0]=>
  object(stdClass)#1 (1) {
    ["id"]=>
    int(8)
  }
  [1]=>
  object(stdClass)#2 (1) {
    ["id"]=>
    int(10)
  }
  [2]=>
  object(stdClass)#3 (1) {
    ["id"]=>
    int(11)
  }
  [3]=>
  object(stdClass)#4 (1) {
    ["id"]=>
    int(12)
  }
}

But now let's have a look a the docs. json_decode has more than one parameter. The second parameter states if objects should be converted to associative arrays. So var_dump(json_decode($json, true)); would give us something like this:

array(4) {
  [0]=>
  array(1) {
    ["id"]=>
    int(8)
  }
  [1]=>
  array(1) {
    ["id"]=>
    int(10)
  }
  [2]=>
  array(1) {
    ["id"]=>
    int(11)
  }
  [3]=>
  array(1) {
    ["id"]=>
    int(12)
  }
}

But now we want to have the value of every of these arrays. While we could do this with a simple loop, PHP has a lot of inbuilt array functions. So let's look, what could be working for us.

Let's take array_map. This function takes a callable (could be function) and an array and returns an array. (For details visit the docs.)

$result = array_map(function ($value) {
    return $value['id'];
}, json_decode($json, true));

var_dump($result);

This would give us

array(4) {
  [0]=>
  int(8)
  [1]=>
  int(10)
  [2]=>
  int(11)
  [3]=>
  int(12)
}

Explanation: We replace every array in the array with the id value in the array.