Adding a class to an image using preprocess function

Question

I am having trouble adding a class to an image using a preprocessor function in Drupal 9. Specifically, I only want certain images to have that class added. The image is being added using paragraphs.

I've tried a few variations of the following and cannot seem to get class added. I've also tried using ['#item'] but it causes an error.

function confluence_preprocess_field__paragraph__field_card_image(&$variables) {    
    foreach($variables['items'] as $key => $item){
        $variables['items'][ $key ]['content']['item']['class'] = 'card-img-top';
    }
}

Answer 1

You can add it via the content's #item_attributes array like so:

foreach($variables['items'] as $key => $item){
  $variables['items'][$key]['content']['#item_attributes']['class'][] = 'card-img-top';
}