CODEWITHSUNDEEP
phprecursionmultidimensional-arraytree
Teretto
Teretto

Reputation: 655

Recursion on subarrays with "child" key

I have array of arrays - tree structure of main menu. I try to find in this tree one node with needed slug and return this node with all it's childs. I write little recurcive function

<?php
$tree = '[{"id":1,"structure":1,"parent":0,"slug":"medicinskaya-ge","child":{"2":{"id":2,"structure":1.1,"parent":1,"slug":"dnk-diagnostika","child":{"3":{"id":3,"structure":"1.1.1","parent":2,"slug":"dnk-diagnostika","datafile":"ssz","template":"ssz"},"4":{"id":4,"structure":"1.1.2","parent":2,"slug":"dnk-diagnostika","child":{"5":{"id":5,"structure":"1.1.2.1","parent":4,"slug":"dnk-diagnostika"},"6":{"id":6,"structure":"1.1.2.2","parent":4,"slug":"testirovanie-ge"},"7":{"id":7,"structure":"1.1.2.3","parent":4,"slug":"dnk-diagnostika"}}},"8":{"id":8,"structure":"1.1.3","parent":2,"slug":"dnk-diagnostika"},"9":{"id":9,"structure":"1.1.4","parent":2,"slug":"texnologiya-kol"}}}}}]';
$tree = json_decode($tree, true);


function getSlugData(string $slug, array $data)
{
    foreach ($data as $row) {
        if ($row['slug'] == $slug) {
            return $row;
        }
        if (isset($row['child'])) {
            //return $this->getSlugData($slug, $row['child']);
        }
    }

    return [];
}


$result = getSlugData('testirovanie-ge', $tree);
print_r($result);

But as a result I have an empty array. If I print_r($row) when $row['slug'] == $slug - It appears on screen.

if ($row['slug'] == $slug) {
    exit(print_r($row));
    return $row;
}

What's my mistake?

Upvotes: 0

Views: 102

Answers (2)

Benilson
Benilson

Reputation: 734

In programming, recursion is a useful and powerful mechanism that allows a function to call itself directly or indirectly, that is, a function is said to be recursive if it contains at least one explicit or implicit call to itself.

I modified your code a bit and got the solution below.

$tree = '[{"id":1,"structure":1,"parent":0,"slug":"medicinskaya-ge","child":{"2":{"id":2,"structure":1.1,"parent":1,"slug":"dnk-diagnostika","child":{"3":{"id":3,"structure":"1.1.1","parent":2,"slug":"dnk-diagnostika","datafile":"ssz","template":"ssz"},"4":{"id":4,"structure":"1.1.2","parent":2,"slug":"dnk-diagnostika","child":{"5":{"id":5,"structure":"1.1.2.1","parent":4,"slug":"dnk-diagnostika"},"6":{"id":6,"structure":"1.1.2.2","parent":4,"slug":"testirovanie-ge"},"7":{"id":7,"structure":"1.1.2.3","parent":4,"slug":"dnk-diagnostika"}}},"8":{"id":8,"structure":"1.1.3","parent":2,"slug":"dnk-diagnostika"},"9":{"id":9,"structure":"1.1.4","parent":2,"slug":"texnologiya-kol"}}}}}]';
$tree = json_decode($tree, true);

//print_r($tree);
//die();

function getSlugData(string $slug, array $data, string $key = 'slug')
{
    $result = [];
    foreach ($data as $row) {
        // Checks if the key exists and is the desired value for that key in the array
        if (isset($row[$key]) && $row[$key] === $slug) {
            return $row;
        }

        // If it is an array, apply recursion by calling getSlugData again
        if (is_array($row)) {
            $result = getSlugData($slug, $row, $key);
            if ($result !== []) {
                return $result;
            }
        }
    }

    return $result;
}

print_r(getSlugData('testirovanie-ge', $tree));
print_r(getSlugData('texnologiya-kol', $tree));
print_r(getSlugData('nothing-here', $tree));
die();

Upvotes: 2

mickmackusa
mickmackusa

Reputation: 47764

In the recursive function, you must not break the loop early unless you find your slug match. If a non-slug-match has a child element, you must iterate it and potentially pass up a match in subsequent recursive calls.

Code: (Demo)

function getSlugData(string $slug, array $data): array
{
    foreach ($data as $row) {
        if ($row['slug'] === $slug) {
            return $row;
        }
        if (isset($row['child'])) {
            $deeper = getSlugData($slug, $row['child']);
            if ($deeper) {
                return $deeper;
            }
        }
    }
    return [];
}

P.s. you aren't calling a class method, so $this-> is inappropriate.

Upvotes: 1

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