How to check if block is empty in page.html.twig

Question

In my page.html.twig I have

<h2>{{ 'Block title'|t }}</h2>
<div class="">
  {{ drupal_block('leftblock') }}
  {{ drupal_block('rightblock') }}
</div>

I want to display Block title only if my custom leftblock and rightblock are filled.

Thanks.

---

I tried

If I do in my my_module.module

function my_module_preprocess_page(&$variables) {
  $block = Block::load('leftblock');
  if ($block) {
    $variables['leftblock'] = \Drupal::entityTypeManager()
      ->getViewBuilder('block')
      ->view($block);
  }
  $block = Block::load('rightblock');
  if ($block) {
    $variables['rightblock'] = \Drupal::entityTypeManager()
      ->getViewBuilder('block')
      ->view($block);
  }
}

and in my page.html.twig

{% if leftblock or rightblock %}
  <h2>{{ 'Block title'|t }}</h2>
{% endif %}
<div class="my-class">
  {{ leftblock }}
  {{ rightblock }}
</div>

This {{ rightblock }} display the real content of the block in twig( when is filled ), but It always display Block title because the block have always something

if I do {{ dump(rightblock) }} i got this when the block is empty or filled.

array(3) { ["#cache"]=> array(4) { ["keys"]=> array(3) { [0]=> string(11) "entity_view" [1]=> string(5) "block" [2]=> string(22) "rightblock" } ["contexts"]=> array(2) { [0]=> string(28) "languages:language_interface" [1]=> string(8) "url.site" } ["tags"]=> array(2) { [0]=> string(10) "block_view" [1]=> string(41) "config:block.block.rightblock" } ["max-age"]=> int(-1) } ["#weight"]=> int(0) ["#lazy_builder"]=> array(2) { [0]=> string(42) "Drupal\block\BlockViewBuilder::lazyBuilder" [1]=> array(3) { [0]=> string(22) "rightblock" [1]=> string(4) "full" [2]=> NULL } } }

I have two themes :

block-myLeft.html.twig

block-myRight.html.twig

Answer 1

There is an EASY Solution for this. You need to save the rendered html of drupal_block into a twig variable first and then check the value of the variable :

{% set leftblock %}
  {{ drupal_block('leftblock') }}
{% endset %}
{% if leftblock|striptags|trim %}
  {{ leftblock }}
{% endif %}

{% set rightblock %}
  {{ drupal_block('rightblock') }}
{% endset %}
{% if rightblock|striptags|trim %}
  {{ rightblock }}
{% endif %}

Answer 2

You could preprocess your template

function mytheme_preprocess_page(&$variables) {
  $block = \Drupal\block\Entity\Block::load('leftblock');
  if ($block) {
    $variables['leftblock'] = \Drupal::entityTypeManager()
      ->getViewBuilder('block')
      ->view($block);
  }
  $block = \Drupal\block\Entity\Block::load('rightblock');
  if ($block) {
    $variables['rightblock'] = \Drupal::entityTypeManager()
      ->getViewBuilder('block')
      ->view($block);
  }
}

Than you can do this in your template

{% if rightblock or leftblock %}
  <h2>{{ 'Block title'|t }}</h2>
{% endif %}
<div class="">
  {{ leftblock }}
  {{ rightblock }}
</div>

Answer 3

It seems this is an issue discussed elsewhere. Perhaps one of those proposals will help you?

Without knowing exactly what a "full" lazybuilder array is supposed to look like, I can only offer a speculative suggestion based on the assumption regarding what the lazybuilder array's null value might imply. If it means there's no data, then perhaps you could try:

{% if leftblock['#lazy_builder'][1][2] is not null or rightblock['#lazy_builder'][1][2] is not null %}
    <h2>{{ 'Block title'|t }}</h2>
{% endif %}

For clarity, here is the variable dump formatted:

array(3) { 
    ["#cache"]=> array(4) { 
        ["keys"]=> array(3) { 
            [0]=> string(11) "entity_view" 
            [1]=> string(5) "block" 
            [2]=> string(22) "rightblock" 
        } 
        ["contexts"]=> array(2) { 
            [0]=> string(28) "languages:language_interface" 
            [1]=> string(8) "url.site" 
        } 
        ["tags"]=> array(2) { 
            [0]=> string(10) "block_view" 
            [1]=> string(41) "config:block.block.rightblock" 
        } 
        ["max-age"]=> int(-1) 
    } 
    ["#weight"]=> int(0) 
    ["#lazy_builder"]=> array(2) { 
        [0]=> string(42) "Drupal\block\BlockViewBuilder::lazyBuilder" 
        [1]=> array(3) { 
            [0]=> string(22) "rightblock" 
            [1]=> string(4) "full" 
            [2]=> NULL 
        } 
    } 
}

Answer 4

I couldn't solve my issue like that. What I did was to use only one block and pass 2 variables with a list of content in each. And then in twig I check if there any elements in each variable. So I display the title in that moment.

Block/myBlock.php

$build[] = [
  '#theme' => 'my_block',
  '#left_content' => $itemsL,
  '#right_content' => $itemsR,
];

My my-block.html.twig

{% if left_content is not empty or right_content is not empty %}
  <h2>{{ 'Block title'|t }}</h2>
{% endif %}