How to get a field value from a custom block?

In Drupal 11, to get a field value from a custom block, we’ll typically be dealing with a block_content entity. Here’s how we can retrieve the field value programmatically.

1. Load the custom block by UUID or ID

use Drupal\block_content\Entity\BlockContent;

// Load by block ID (e.g., 1)
$block = BlockContent::load(1);

if ($block && $block->hasField('field_example_text')) {
  $value = $block->get('field_example_text')->value;
  \Drupal::messenger()->addMessage("Field value: " . $value);
}

2. Load by custom block UUID

use Drupal\block_content\Entity\BlockContent;

$uuid = 'your-block-uuid-here';
$blocks = \Drupal::entityTypeManager()
  ->getStorage('block_content')
  ->loadByProperties(['uuid' => $uuid]);

$block = reset($blocks);

if ($block && $block->hasField('field_example_text')) {
  $value = $block->get('field_example_text')->value;
}

3. Using block plugin in preprocess

function MYTHEME_preprocess_block(array &$variables) {
  $block = $variables['elements']['#block_content'] ?? NULL;

  if ($block instanceof \Drupal\block_content\Entity\BlockContent && $block->hasField('field_example_text')) {
    $variables['example_text'] = $block->get('field_example_text')->value;
  }
}