How can I get the numeric ID for a block from within the block template or hook_preprocess_block?

Question

How can I get the numeric ID for a block from within the block template or hook_preprocess_block().

By numeric ID, I mean the ID that we see in the edit link for a block. For example, mysite.com/admin/content/block/123

Drupal version: 10

Answer 1

You can check yourself with Xdebug or Kint.

/**
 * Implements hook_preprocess_HOOK().
 */
function MYMODULE_preprocess_block(&$variables) {

  // Check if it's a content block.
  if ($variables['elements']['#base_plugin_id'] === 'block_content') {

    /** @var \Drupal\block_content\Entity\BlockContent $block_content */
    $block_content = $variables['content']['#block_content'];

    // Get the numeric ID.
    $id = $block_content->id();

    // Code on ...
  }
}