Re-looping through an array (PHP) - php

Question

I have a strange array. I get some objects that have children, and then I have some objects that are the id's of the children.
array {
"1": {
"children": [
10,
11,
],
"parent_id": null,
}
}
"2": {
"children": [
12,
13,
]
"parent_id": null,
}
"10": {
"name": Tom,
"parentid": 1,
}
"11": {
"name": Peter,
"parentid": 1,
}
}
I'm trying to first list out the objects if they have children via a foreach.
foreach ($array as $key) {
if (parent_id === null){
echo id;
}
}
So I get a list that looks like this:
1
2
(no 10 and 11)
But now what I want to do is list the name of the children under their parent, so it ends up something like this:
1
Tom
Peter
2
I have an array of the children ids, I'm just not sure how to reloop through the original array for the names.

Answer 1

Will assume your array is one level deep, a parent_id == null signifies a parent and there are no possible orphan elements that should be displayed:
foreach($array as $key => $value) {
if ($value['parent_id'] === null) {
echo $key;
// we got a parent, iterate through it's children
foreach($value['children'] as $childId) {
echo $array[$childId]['name'];
}
}
}
May want to add some empty checks, just to make sure all keys exist in the array.