How to compare number of array elements with each other in validation?

Question

Laravel

There are 2 fields with multiple filled values. How can it be compared that the number of elements in the first array is equal to the number of elements in the second array?

class MyRequest extends FormRequest
{
    public function rules(): array
    {
        return [
           // 'categories' => 'required|same:titles', // Тут бы equal:field какой-нибудь... Нашёл только qte:field и lte:field
            'categories.*' => 'required|string|exists:categories,slug',
            'titles.*' => 'required|string|max:255',
        ];
    }
}

UPDATE: Did this:

$rules = [
    'categories' => 'required|array|min:1',
    'titles' => 'required|array|min:1',
];

foreach($this->request->get('categories') as $key => $val) {
    $rules['categories.' . $key] = 'required|integer|exists:categories,id';
    $rules['titles.' . $key] = 'required|string|max:255';
}
return $rules;

Answer 1

https://laravel.com/docs/5.8/validation#custom-val...