如何实现array_filter（）以使其更清晰

I need a little help in the PHP, because I'm trying to use the array_filter() to prevent to many lines and make it simply and clear, but I'm struggling in this one, even if I'm reading this documentation: Array_Filter so I need a correct way to implement, because sometimes the getCategoryTree() comes empty or with null values, which I'm trying to not show it, I thought to create other function to show only specific things without category, but I feel that it is not efficient:

What I'm trying is to populate from the url www.foobar.com/checkout/payments, and this is the original code:

$page['eData'] = [
    'codeMoneyFormatter' => $this->moneyFormatter->getcodeMoneyFormatter(),
    'checkout' => [
        'actionField' => ['step' => 3, 'option' => 'Review Order'],
        // ---------------- THIS ONE MUST REFACTOR -------
        'products' => $this->getCartFromOrder($order),
    ],
];

// --------------------- REFACTOR ------------------
$itemData['category'] = $category ? $this->getCategoryTree($category->getId()) : '';
// -------------------------------------------------

This function is where it shows the category, but I don't like it because at all, because in some pages it comes empty/null which it's not correct, so I want to use the array_filter()

// --------------------- ARRAY_FILTER ------------------
$itemData['category'] = array_filter($category ? $this->getCategoryTree($category->getId()) : '');
// -------------------------------------------------

The function that I created to show only specific thing, it's correct because it does not show the category, but I feel that it's unnecessary because its repeating the same from the original one:

$page['eData'] = [
    'codeMoneyFormatter' => $this->moneyFormatter->getcodeMoneyFormatter(),
    'checkout' => [
        'actionField' => ['step' => 3, 'option' => 'Review Order'],
        'products' => $this->getCheckoutFromOrder($order),
    ],
];

It's repeating almost the same functions and it's not the correct standard of DRY (Don't repeat yourself) that's why I thought to implement the array_filter() but how???

Array_Filter so I need a correct way to implement, because sometimes the getCategoryTree() comes empty or with null values

Easy, don't change types and feed array filter something it shouldn't eat.

 array_filter($category ? $this->getCategoryTree($category->getId()) : '');

Should be (something like)

 $data = $category ? $this->getCategoryTree($category->getId()) : [];
 if(!is_array($data)) $data = [];

 array_filter($data);

You can probably do it simpler then this. But, type changes in PHP can be troublesome because the language is loosely typed and won't complain to much.

This can be easly tested

var_dump(array_filter(''));

output

<br />
<b>Warning</b>:  array_filter() expects parameter 1 to be array, string given in <b>[...][...]</b> on line <b>3</b><br />
NULL

Sandbox

This on the other hand

 var_dump(array_filter([]));

Simply returns an empty array.

The last thing I will say is about 80% of the code you put in the question was unnecessary to answer the question and just serves to confuse other users.