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);