How to convert php array to tree structure

How to convert php array to tree structure: 1. Create a PHP sample file; 2. Construct a function with the syntax "function buildTree(array $elements, $parentId = 0)" Parameter 1 is to be converted Array, parameter 2 is the specified root node; 3. Define the $branch empty array in the function to store the tree structure and traverse it; 4. After traversing, add the modified elements to the $branch array and return the tree structure Just use the structure array $branch.

Operating system for this tutorial: Windows 10 system, php8.1.3 version, Dell G3 computer.

Convert PHP array to tree structure, which can be achieved through recursive method.

The following is an example of a PHP function:

function buildTree(array $elements, $parentId = 0) {
    $branch = array();
    foreach ($elements as $element) {
        if ($element['parent_id'] == $parentId) {
            $children = buildTree($elements, $element['id']);
            if ($children) {
                $element['children'] = $children;
            }
            $branch[] = $element;
        }
    }
    return $branch;
}

In this function, the parameter $elements is the array to be converted, and $parentId is the specified root node (default is 0) . The function first defines an empty array named $branch to store and traverse the tree structure.

In each loop, the function checks whether the current element has the specified parent ID. If so, it means that it is a child node of the current node. It then calls its own buildTree() function to add child nodes and assigns the child nodes to the $children variable. The function continues to check whether $children is empty, and if not, assigns the child node to the 'children' key of the current element. Finally, the function adds the modified elements to the $branch array.

When all elements are processed, the function will return the tree structure array $branch.

Suppose we have the following data:

$elements = [
    ['id' => 1, 'name' => 'Parent 1', 'parent_id' => 0],
    ['id' => 2, 'name' => 'Child 1', 'parent_id' => 1],
    ['id' => 3, 'name' => 'Grandchild 1', 'parent_id' => 2],
    ['id' => 4, 'name' => 'Grandchild 2', 'parent_id' => 2],
    ['id' => 5, 'name' => 'Parent 2', 'parent_id' => 0],
];

This function can be called to generate a tree structure.

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