Find specific element from multidimensional array in PHP

Question

I have a multidimensional array that I use to build a navigation menu. It may consist of any number of submenus (or children). The menu works just fine. When someone clicks on a menu link, the product category with id "menuid" opens. However, I also need to know the menuid of all the children of the current menuid (but not it's grandchildren and so forth).

This is an example of the array:

    Array
(
   [0] => Array
      (
         [menutype] => url
         [menuid] => 46
      )
   [1] => Array
      (
         [menutype] => product_category
         [menuid] => 55
         [children] => Array
            (
               [0] => Array
                  (
                     [menutype] => product_category
                     [menuid] => 69
                     [children] => Array
                        (
                           [0] => Array
                              (
                                 [menutype] => product_category
                                 [menuid] => 211
                              )
                           [1] => Array
                              (
                                 [menutype] => product_category
                                 [menuid] => 57
                              )
                           [2] => Array
                              (
                                 [menutype] => product_category
                                 [menuid] => 166
                              )
                        )
                  )
               [1] => Array
                  (
                     [menutype] => product_category
                     [menuid] => 57
                  )
               [2] => Array
                  (
                     [menutype] => product_category
                     [menuid] => 94
                  )
            )
      )
   [2] => Array
      (
         [menutype] => posts_category
         [menuid] => 45
      )
)

For example, I would like to know how to get the menuid value of the elements in children for the element with menuid 69. (Should return an array with 211, 57 and 166).

The easiest way is to build a recursive function Basically a function that you will pass an array into, and then if there's a child array you'll call the function from within the function. There's many examples online. — Zak
– Zak, Commented Mar 19, 2019 at 18:04
AbraCadaver The code for the menu is too extensive to post here, especially since it's not relevant. :) The array in my post has been edited, there are a lot more data in each element of the original array (in addition to menutype, menuid and children). — Endre Ottem
– Endre Ottem, Commented Mar 19, 2019 at 18:50

khartnett · Accepted Answer · 2019-03-19 19:04:47Z

1

You can accomplish this with a recursive function like so:

function getChildIds($menuItems, $parentId) {
    foreach ($menuItems as $menuItem) {
        if (isset($menuItem['children'])) {
            $result = getChildIds($menuItem['children'], $parentId);
            if ($result !== false) {
                return $result;
            }
        }
        if ($menuItem['menuid'] == $parentId) {
            $result = [];
            if (isset($menuItem['children'])) {
                foreach ($menuItem['children'] as $childItem) {
                    $result[] = $childItem['menuid'];
                }
            }
            return $result;
        }
    }
    return false;
}

Note this will return an empty array if the menuid is found but has no children, or false if the id is not found.

edited Mar 19, 2019 at 19:04

answered Mar 19, 2019 at 18:04

khartnett

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1 Comment

Endre Ottem Over a year ago

Wow, that was quick. Worked right out of the box (had to correct the misspelling of "children", though). :-)

kavindalb · Accepted Answer · 2019-03-19 19:07:21Z

Also You can use recursive function with more efficient way like this:

$menu = [
    [
        'menutype' => 'url',
        'menuid'   => 46,
    ],
    [
        'menutype' => 'product_category',
        'menuid'   => 55,
        'children' => [
            [
                'menutype' => 'product_category',
                'menuid'   => 69,
                'children' => [
                    [
                        'menutype' => 'product_category',
                        'menuid'   => 211
                    ],
                    [
                        'menutype' => 'product_category',
                        'menuid'   => 57
                    ],
                    [
                        'menutype' => 'product_category',
                        'menuid'   => 166
                    ]
                ]
            ],
            [
                'menutype' => 'product_category',
                'menuid'   => 57
            ],
            [
                'menutype' => 'product_category',
                'menuid'   => 94
            ]
        ]
    ],
    [
        'menutype' => 'posts_category',
        'menuid'   => 45
    ]
];

function getMenu(array $menu, $menuId, $children = true)
{
    foreach ($menu as $menuItem) {
        if (array_key_exists('menuid', $menuItem) && $menuItem['menuid'] == $menuId) {
            if ($children === true && array_key_exists('children', $menuItem)){
                return $menuItem['children'];
            }

            return $menuItem;
        }

        if (array_key_exists('children', $menuItem)) {
            return getMenu($menuItem['children'], $menuId, $children);
        }
    }
}

getMenu($menu, 69);

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