How can I programmatically display a block?

Question

I'm developing a site using Drupal 8 beta-14. I've created a view block of different terms and now I want to display it using code. How can I display it programatically? I used to do it in Drupal 7 using this code but I'm confused about Drupal 8.

$block = module_invoke('block', 'block_view', '4');
$text_block = render($block['content']);

Answer 1

There are two types of blocks, and the method for rendering the two is a bit different:

Content Blocks

Content blocks are blocks that you create in the interface. They are much like nodes configurable data structures, with fields etc. If you want to render one of these, you can do what you would normally do with entities, load them and render them with the view builder:

$bid = ??? // Get the block id through config, SQL or some other means
$block = \Drupal\block_content\Entity\BlockContent::load($bid);
$render = \Drupal::entityTypeManager()->
  getViewBuilder('block_content')->view($block);
return $render;

Plugin blocks

Blocks can also be plugin, defined in various modules. An example could be the breadcrumb block. If you want to render these, you will need to use the block plugin manager.

$block_manager = \Drupal::service('plugin.manager.block');
// You can hard code configuration or you load from settings.
$config = [];
$plugin_block = $block_manager->createInstance('system_breadcrumb_block', $config);
// Some blocks might implement access check.
$access_result = $plugin_block->access(\Drupal::currentUser());
// Return empty render array if user doesn't have access.
// $access_result can be boolean or an AccessResult class
if (is_object($access_result) && $access_result->isForbidden() || is_bool($access_result) && !$access_result) {
  // You might need to add some cache tags/contexts.
  return [];
}
$render = $plugin_block->build();
// Add the cache tags/contexts.
\Drupal::service('renderer')->addCacheableDependency($render, $plugin_block);
return $render;

Config entities

Shared for the two types are blocks, are that once you insert them into a region, you will create a config entity that has all of the settings for the block. In some cases it will be more useful handling config entities. Since the same block can be place in multiple regions with and with different configuration, it can get more tricky using the block config entities. The nice thing is that you might want to render a block with specific configuration, the bad thing is that config ids can change by messing with the interface, so the code might end up not working after letting users use the block interface.

$block = \Drupal\block\Entity\Block::load('config.id');
$render = \Drupal::entityTypeManager()
  ->getViewBuilder('block')
  ->view($block);
return $render;

Answer 2

For display only your block in your templates with preprocess the best way is

$block = \Drupal\block\Entity\Block::load('my_block_id');
$variables['My_region'] = \Drupal::entityTypeManager()
          ->getViewBuilder('block')
          ->view($block); // Works in Drupal 9

And in your page.html.twig or node.html.twig or xxx.html.twig use your variable My_region like this :

{% if page.My_region %}
    {{ page.My_region }}
{% endif %}

And in renderable array (custom module) by example into an controller custom in content() :

public function content() {
    $block = \Drupal\block\Entity\Block::load('my_block_id');
    $block_content = \Drupal::entityManager()
      ->getViewBuilder('block')
      ->view($block);

          return array(
        '#type' => 'container',
        '#attributes' => array(
          'class' => array("Myclass"),
        ),
        "element-content" => $block_content,
        '#weight' => 0,
      );
}

Using drupal_render is not useful as Drupal already assume the render in D8 and this is deprecated. You should use \Drupal::service('renderer')->renderRoot() instead.

It's a bit heavy, it is better to use the maximum area system and does not add load block from the preprocess. In the case of using a controller in your modules this seems a justified use.

Answer 3

I needed to get the HTML of a custom block and got it using:

$con = \Drupal\block\BlockViewBuilder::lazyBuilder('bartik_search', 'full');
$d   = \Drupal::service('renderer')->renderPlain($con);

print $d->__toString();

Answer 4

In addition to the top answer... If you want to render a block from a view, you may have to do things a little differently.

$view = views_embed_view('my_view_name', 'my_display_name');

(display name eg -> block_1)

Since we're going to pass it to twig, we don't need to render (using render service).

So you can just pass it as a variable to twig (for this example, its the return of a Controller):

return [
  ['description' => [
    '#theme' => 'your_theme_hook',
    '#your_variable => $view
  ]
]

in your module you need a hook_theme() for your variable:

function hook_theme($existing, $type, $theme, $path) {
  return array(
    'your_theme_hook' => array(
      'variables' => [
        'your_variable' => NULL,
      ]
    )
  )
}

And finally in your twig template:

{{ your_variable }}

Answer 5

Basically, there are two types of renders.

1. When there is an existing instance of the block in the layout. the block can be rendered in twig using preprocess as

   $block = Block::load('BLOCK_ID');
   $variables['social_links'] = \Drupal::entityTypeManager()
     ->getViewBuilder('block')
     ->view($block);
   

2. There is no instance or configurations for the block. Then in the preprocessor, we need to create the instance, build the block and then render it

   $block_manager = \Drupal::service('plugin.manager.block');
   $config = [];
   $plugin_block = $block_manager->createInstance('farmjournal_social_sharing', $config);
   $render = $plugin_block->build();
   $variables['farmjournal_social_sharing'] = render($render);
   

Answer 6

The following code works for blocks.

$block = \Drupal\block\Entity\Block::load('some_block_id_3');
$plugin = $block->getPlugin();
$build = $plugin->build();
$build['#weight'] = 4;
$form['block'] = $build;

Answer 7

// You need a block_id! to get it just click configure in the desire block and you'll get url like this /admin/structure/block/manage/bartik_search   the last part of the parameter is the block id
$block = \Drupal\block\Entity\Block::load('bartik_search');
$block_content = \Drupal::entityManager()
  ->getViewBuilder('block')
  ->view($block);

return array('#markup' => \Drupal::service('renderer')->renderRoot($block_content));

Answer 8

You get the block output and then you may return it.

$block = \Drupal\block\Entity\Block::load ('my_bock_id');
block_content = \Drupal::entityManager()->getViewBuilder('block')->view($block);

return [
  '#type' => 'container',
  'element-content' => $block_content
];

Answer 9

Adding an additional answer here for better visitbility:

There is now a module that allows you to render a plugin block called Block plugin view builder: https://www.drupal.org/project/block_plugin_view_builder.

You can of course still use Drupals render service, however that returns a \Drupal\Component\Render\MarkupInterface object. In some cases, you need a render array. For example if wanting to render the block in the lazy builder.

Example of using that modules service once that module is installed:

$block_view_builder = \Drupal::service('block_plugin.view_builder');
$block = $block_view_builder->view('bid', []);
return $block;

Answer 10

Based on my research, you could base the code from How to render a block programmatically in drupal 8. You could also change

return array('#markup' => \Drupal::service('renderer')->renderRoot($block_content));

into something as simple as:

$output .= \Drupal::service('renderer')->renderRoot($block_content);

to attach it for example into a page's return variable.