How do I properly detect if region is empty? [closed]

Question

I have condition for printing regions in my page template as is not empty, but it will always print empty regions no matter what. What is the proper way to detect empty regions?

For example, {% if page.local_tasks is not empty %}{{ page.local_tasks }}{% endif %} prints out <div class="region region-local-tasks"></div>.

If I render the region in themename_preprocess_page() with var_dump(drupal_render($variables['page']['highlighted'])); I will get SafeString with placeholder token:

<div class="region region-highlighted"><drupal-render-placeholder callback="Drupal\Core\Render\Element\StatusMessages::renderMessages" arguments="0" token="a8c34b5e"></drupal-render-placeholder></div>

So, technically the region is not empty but I can do nothing about it.

Answer 1

try to apply filters after render, like this :

{% set has_sidebar_first = page.sidebar_first|render|striptags|trim is not empty %}
{% if has_sidebar_first %}
    {# ... #}
{% endif %}

Answer 2

TL;DR for this is that there is no way to reliably check if region is empty or not in the template.

In Drupal 8 at the point when we are at the template level we are unable to tell whether the region has content or not because the content is rendered lazily. There is open Drupal 8 issue for this.

What you probably will have to do to achieve this is to write CSS that tests whether the region is empty. You can try using using :empty pseudo-selector.

Answer 3

This worked for me.

{% if page.sidebar_first|render|striptags %}
<aside id="sidebar-first" class="sidebar sidebar-first layout-sidebar-first" role="complementary">{{ page.sidebar_first }}</aside>
{% endif %}

Simple enough.

Answer 4

In twig you should really be able to do:

{% if page.local_tasks %}{{ page.local_tasks }}{% endif %}

However perhaps there is something within page.local_tasks (like empty markup). Please try the following:

{% if page.local_tasks|striptags|trim %}{{ page.local_tasks }}{% endif %}

Answer 5

try this :

 {% if page.local_tasks|render|striptags|trim  is not empty %}
    {{ page.local_tasks }}
 {% endif %}

Answer 6

This actually works in my case

{% if page.sidebar_second|render|striptags('<drupal-render-placeholder>')|trim|length > 0 %}

striptags accepts a string of tags to keep, so you can also add whatever contentless tags you expect to have, like <form><img> etc.

Answer 7

You should use Renderer service instead of drupal_render() which is deprecated, so:

$output = \Drupal::service('renderer')->renderRoot($some_array)

This will avoid generating drupal-render-placeholder tag in the output.

Similar issue: How to replace drupal-render-placeholder manually?

Answer 8

The following does also work when twig debugging is enabled:

{% set sidebarLength = page.sidebar_first|render|trim|striptags|length %}
{% if sidebarLength > 1 %}
  {% set has_sidebar_first = page.sidebar_first %}
{% else %}
  {% set has_sidebar_first = null %}
{% endif %}

Answer 9

To detect if region is empty or not code like this:

{% if page.local_tasks %}
   {{ page.local_tasks }}
{% endif %}

In above code it checks if local_tasks region is empty or not and if empty then it will not print that region