Build a multi dimensional array from tree - php

Question

I have some data on a MySQL database representing a tree structure, and I want to convert it into JSON. I have used a recursive function to read all the data but I have no idea on how to convert into an array.
Here is the recursive function:
public function buildTree($parent, $level) {
// retrieve all children of $parent
$results = Department::all()->where('parent_id',$parent);
// display each child
foreach($results as $result)
{
echo $this->buildTree($result['id'], $level+1);
}
}
And the following is the JSON result I'd like to have in the end:
[
{
"id":1,
"text":"Root node",
"children":[
{
"id":2,
"text":"Child node 1",
"children":[
{
"id":4,
"text":"hello world",
"children":[{"id":5,"text":"hello world2"}]
}
]
},
{
"id":3,
"text":"Child node 2"
}
]
}
]
Here is the sample data

Answer 1

public function buildTree($parent, $level) {
// The array which will be converted to JSON at the end.
$json_return = array();
// Get the current element's data.
$results = Department::all()->where('id',$parent);
$json_return['id'] = $parent;
$json_return['text'] = $results[0]['text']; // Or however you access the "text" parameter of the end JSON from the database.
// Retrieve all children of $parent
$results = Department::all()->where('parent_id',$parent);
if (count($results) > 0)
{
$json_return['children'] = array();
foreach($results as $result)
{
$json_return['children'][] = $this->buildTree($result['id'], $level+1);
}
}
// Going to assume that $level by default is 0
if ($level == 0)
{
echo json_encode(array($json_return));
}
return $json_return;
}