Making a nested array in php

Probably my question is too much common or easy for you, but I really have no idea how to do it. Trying all everything I know and lots of googling didn't help me.

I just need a nested array.

Here is my PHP code:

EDITED
Corrected: $data['product_names'][$language['language_id']][] = array(

$data['product_names'] = array();

foreach ($data['languages'] as $language) {
    $product_names_info = $this->model_catalog_category->getCategoryMultiLang($this->request->get['product_id'], $language['language_id']);

    if ($product_names_info) {
        $data['product_names'][$language['language_id']][] = array(
            'category_id' => $product_names_info['category_id'],
            'language_id' => $product_names_info['language_id'],
            'name'        => $product_names_info['name']
        );
    }
}

print_r($data['product_names']);

The result that I get:

Array
(
    [5] => Array
        (
            [0] => Array
                (
                    [category_id] => 
                    [language_id] => 
                    [name] => 
                )

        )

    [2] => Array
        (
            [0] => Array
                (
                    [category_id] => 
                    [language_id] => 
                    [name] => 
                )

        )

    [4] => Array
        (
            [0] => Array
                (
                    [category_id] => 
                    [language_id] => 
                    [name] => 
                )

        )

    ... 

The result should look like this:

Array
(
    [0] => Array
        (
            [language_id] => 1
            [category_id] => 8
            [name] => book
        )

    [1] => Array
        (
            [language_id] => 5
            [category_id] => 188
            [name] => magazine
        )

...
)
Array
(
    [0] => Array
        (
            [language_id] => 1
            [category_id] => 8
            [name] => buch
        )

...

UPDATED
The result of print_r($product_names_info); inside foreach ($data['languages'] as $key => $language) {

Array
(
    [0] => Array
        (
            [language_id] => 5
            [category_id] => 8
            [name] => Gecelik
        )

    [1] => Array
        (
            [language_id] => 5
            [category_id] => 188
            [name] => Sabahlık
        )

    ...

)
Array
(
    [0] => Array
        (
            [language_id] => 2
            [category_id] => 8
            [name] => لباس خواب
        )

    [1] => Array
        (
            [language_id] => 2
            [category_id] => 188
            [name] => Sabahlık
        )

Thanks for any kind help.

Option 1:

$data['product_names'] = [];

foreach ($data['languages'] as $language) {
    $languageId = (int) $language['language_id'];

    // Fetch once per language
    $rows = $this->model_catalog_category
        ->getCategoryMultiLang(
            (int) $this->request->get['product_id'],
            $languageId
        );

    if (empty($rows)) {
        continue; // skip empty results early
    }

    // Direct assignment instead of pushing in nested loop
    $data['product_names'][$languageId] = array_map(
        static function ($row) {
            return [
                'category_id' => $row['category_id'],
                'language_id' => $row['language_id'],
                'name'        => $row['name'],
            ];
        },
        $rows
    );
}

print_r($data['product_names']);
/*
Before: O(L × N)
After: O(L × N) (same big-O, lower constant cost)

Same O(L × N)
But:
Fewer intermediate array operations
No repeated [] pushes
Cleaner memory allocation
*/

I think you were missing foreach for the data you fetched into var $product_names_info

---

Option 2:

If you want maximum performance

If getCategoryMultiLang() can be changed, best possible solution is:

Fetch everything in ONE query

$results = $this->model_catalog_category
    ->getCategoryMultiLangForAllLanguages($productId);

foreach ($results as $row) {
    $data['product_names'][$row['language_id']][] = [
        'category_id' => $row['category_id'],
        'language_id' => $row['language_id'],
        'name'        => $row['name'],
    ];
}

✅ DB calls reduced from L → 1
Biggest real-world performance win.