At some point of my coding, I need to build ‘menu – submenu’ or a tree from my database query result. I faced this problem couple weeks before and realized this is hard to achieved. I have tried the if else statement and foreach loop but failed. Just now, I found a way to solve this. We can use recursive function to build a tree. Here is my solution.
This is the original array:
$original = [
['parent_id' => 0, 'category_id' => 1, 'name' => 'cat 1'],
['parent_id' => 0, 'category_id' => 2, 'name' => 'cat 2'],
['parent_id' => 0, 'category_id' => 3, 'name' => 'cat 3'],
['parent_id' => 1, 'category_id' => 4, 'name' => 'cat 4'],
['parent_id' => 1, 'category_id' => 5, 'name' => 'cat 5'],
['parent_id' => 2, 'category_id' => 6, 'name' => 'cat 6'],
['parent_id' => 2, 'category_id' => 7, 'name' => 'cat 7']
];
This is what I want to achieved:
$result = [
['parent_id' => 0, 'category_id' => 1, 'name' => 'cat 1', ['children'=>
['parent_id'=> 1, 'category_id' => 4, 'name' => 'cat 4'],
['parent_id'=> 1, 'category_id' => 5, 'name' => 'cat 5']
]
],
['parent_id' => 0, 'category_id' => 2, 'name' => 'cat 1', ['children'=>
['parent_id'=> 2, 'category_id' => 6, 'name' => 'cat 6'],
['parent_id'=> 2, 'category_id' => 7, 'name' => 'cat 7']
]
],
['parent_id' => 0, 'category_id' => 3, 'name' => 'cat 1']
];
We can use recursive function to achieved this.
function buildTree(array $elements, $parentId = 0) {
$branch = array();
foreach ($elements as $element) {
if ($element['parent_id'] == $parentId) {
$children = buildTree($elements, $element['category_id']);
if ($children) {
$element['children'] = $children;
}
$branch[] = $element;
}
}
return $branch;
}
$result = buildTree($original);