PHP警告：count（）：参数必须是数组或实现Countable的对象？

Question

On my website I allow people to upload image galleries. When they click an image there is a next and previous button at the bottom so they can easily scroll back and forth through the images.

I am getting the below error in my log located at /opt/cpanel/ea-php72/root/usr/var/log/php-fpm/

NOTICE: PHP message: PHP Warning:  count(): Parameter must be an array or an object that implements Countable in . . . on line 12

It is talking about the line below in my code:

$max = count($photos);

Below is the other code that comes with that line:

$photos = get_field('gallery');
$max = count($photos);    <------- error line here -------->
$current = (isset($_GET['image'])) ? intval($_GET['image']) : false;
if ($current !== false) {
    if ($current > $max) $current = $max;
    if ($current < 1) $current = 1;
}

$next = (($current + 1) < $max) ? ($current + 1) : $max;
$prev = (($current - 1) > 1) ? ($current - 1) : 1;
?>

Basically this code uses get_field('gallery') to get the total amount of photos in the gallery and the number is assigned to variable max .

The rest of the code is how the next and previous buttons work.

I do not know what is wrong. Can somebody help with this?

Answer 1

In the general, solution is simple:

First debbug with var_dump() what $photos return. Than you will know what's the issue.

count() accept array and if you have false , null or anything else you will have error.

Just do something like this:

$photos = get_field('gallery');
if(!is_array($photos) || empty($photos)) $photos = array(); // FIX ERROR!!!
$max = count($photos);    <------- error line here -------->
$current = (isset($_GET['image']) && !empty($_GET['image']) && is_numeric($_GET['image'])) ? intval($_GET['image']) : 0;
if ($current > 0) {
    if ($current > $max) $current = $max;
    if ($current < 1) $current = 1;
}

$next = (($current + 1) < $max) ? ($current + 1) : $max;
$prev = (($current - 1) > 1) ? ($current - 1) : 1;
?>

With if(!is_array($photos) || empty($photos)) $photos = array(); before $max = count($photos); you fixing your issue and anything what is not array or empty (0, NULL, FALSE, '') will be fixed and you will have in the count $max result 0 because array is empty.

---

IMPORTANT!!!

You should not work like this. You need to know what information you receive and expect in variables. The code must remain clean and correcting such errors is a bad practice. If you receive an array, then the array is expected and you must have checks before any calculating.

---

UPDATE:

Also you have error in

$current = (isset($_GET['image'])) ? intval($_GET['image']) : false;
if ($current !== false)

I fix it to work like this:

$current = (isset($_GET['image']) && !empty($_GET['image']) && is_numeric($_GET['image'])) ? intval($_GET['image']) : 0;
if ($current > 0)

Reason for that is that you have calculations below and you not expect (false + 1) to be something good. false can be translated to 0 but in your case you can also get error. For that case I replace false with 0 , add empty() and is_numeric() check and you have no errors there.