I am trying to override block content by using hook_preprocess_block(&$variables). I was expecting to find bundle type in $variable, but not getting anything related to this.

Here is kint display of $variable inside the function - enter image description here

More Info - This is a block type (say content_slider) created from Drupal UI & a block (say content_slider_homepage) is added.

2 Answers 2


The UUID from the custom block is in the variable derivative_plugin_id. You can use this UUID to load the block and get the bundle:

$block = \Drupal::service('entity.repository')->loadEntityByUuid('block_content', $uuid);

if ($block) {
  $block_type = $block->bundle();

Or look in $variables['elements']. Here you'll find the custom block entity loaded in the variables and probably the block type as well. You can also use hook_block_content_view() if this is for a module. See the comments from @Berdir.

  • there is no preprocess_block_content because there is no block_content template, but there is hook_block_content_view() and .. view_alter() and you can get it in preprocess_block() too
    – Berdir
    Commented Feb 24, 2017 at 10:47
  • Specifically, what you are looking for is in elements, so dump that key to see its content
    – Berdir
    Commented Feb 24, 2017 at 10:47

This is how I would do it:

use \Drupal\block_content\BlockContentInterface;

 * Implements HOOK_preprocess_block().
 * @param $variables
function mymodule_preprocess_block(&$variables) {
  $content = $variables['elements']['content'];
  if (isset($content['#block_content']) && $content['#block_content'] instanceof BlockContentInterface) {

    if ($content['#block_content']->bundle() == 'xxx') {
      // ...


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