Find a key in nested json - php

Question

Below is my JSON and i wan to get all key as "node"and "id" of that node.
[
{
"id": 15,
"title": " Introduction",
"node": {
"id": 15,
"title": " Introduction",
"description": " Introduction on travelling abroad",
"media_info": " Introduction on travelling abroad",
"thumb_url": "test",
"media_url": "test"
},
"children": [
{
"id": 16,
"title": "Travel Preparation",
"node": {
"id": 16,
"title": "Travel Preparation",
"description": " Travel Preparation",
"media_info": "Travel Preparation",
"thumb_url": "test",
"media_url": "test"
},
"children": [
{
"id": 17,
"title": "The Act of Traveling",
"node": {
"id": 17,
"title": "The Act of Traveling",
"description": " The Act of Traveling",
"media_info": "The Act of Traveling",
"thumb_url": "/test",
"media_url": "test"
}
}
]
},
{
"id": 18,
"title": "Arrival at Your Destination Abroad",
"node": {
"id": 18,
"title": "Arrival at Your Destination Abroad",
"description": " Arrival at Your Destination Abroad",
"media_info": "Arrival at Your Destination Abroad",
"thumb_url": "test",
"media_url": "test"
},
"children": [
{
"id": 19,
"title": "In Your Destination Country",
"node": {
"id": 19,
"title": "In Your Destination Country",
"description": " In Your Destination Country",
"media_info": "In Your Destination Country",
"thumb_url": "http:test",
"media_url": "test"
}
}
]
}
]
}
]
========================================================================
I am using below code but it is not giving the correct output.
I want out put should be 15,16,17,18.
$obj = json_decode($config_info, true);
foreach ($obj as $key => $value) {
print_r($value['node']['id']);
}

Answer 1

You could try with array_walk_recursive function :
$ids = array();
$data = json_decode($json, true);
array_walk_recursive($data, function($v, $k) use (&$ids) {
if ($k === 'id') {
$ids[] = $v;
}
});
$ids = array_unique($ids);
var_dump($ids);

Answer 2

In your code, $value['node']['id'] refer to the ['node']['id'] key, so it will give you only one output.
In you want others, you have to fetch "children" key as well. Like this for instance :
$obj = json_decode($json, true);
foreach ($obj as $key => $value) {
echo $value['node']['id']; // return 15
$children = $value['children'];
if(is_array($children)){
foreach ($children as $child){
if(is_array($child['children'])){
foreach($child['children'] as $secondLevelChild){
echo $secondLevelChild['id'];// return 17 and 19;
}
}
echo $child['id']; // return 16 and 18
}
}
}
And you can use the same method to retrieve the 17 result as well in the second level of children key, see the code above.

Answer 3

Check it out:
$arr = json_decode($json, true);
$ids = array();
function get_ids($arr){
global $ids;
foreach($arr as $key => $value){
if($key == 'node')
$ids[] = $value['id'];
if(is_array($value))
get_ids($value);
}
}
get_ids($arr);
echo '<pre>';
print_r(array_unique($ids));
Result:
Array
(
[0] => 15
[2] => 16
[4] => 17
[6] => 18
[7] => 19
)