raphaellarrinaga/drupal_8_twig_cheatsheet.md

## drupal_8_twig_cheatsheet.md

      
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              drupal_8_twig_cheatsheet.md
            
          
    Drupal 8 Twig cheatsheet
Please note I created that sheet as a personal side note/draft and not everything is fully tested.
There could be errors or better things to do.
So if you spot something wrong or something that can be improved, feel free to comment below and I will do the changes.
Getting Drupal 8 field values in Twig
Image path: {{ file_url(content.field_name['#items'].entity.uri.value) }}
Image title text: {{ node.field_name.title }}
Entity Reference path: {{ content.field_tags[0]['#url'] }}
@see https://blog.usejournal.com/getting-drupal-8-field-values-in-twig-22b80cb609bd
Check if field is filled
{% if not node.field_name.isEmpty() %}

Old solution below (does not work), will be true most of the time since the render array is not empty (e.g. gets #cache or #weight rows).
  {% if content.field_image|length %}
  <div class="banner">{{ content.field_image[0] }}</div>
  {% endif %}

Credit @lincoln-chawora 🙏
Check for some content existence
Those solutions are not perfect.
@see https://www.drupal.org/project/drupal/issues/953034?page=1

e.g. for a region or a field that contains text content.field_fee|render|striptags|trim
e.g. for a field image using field value module content.header.field_image|field_value

Custom date format
{% set date = node.createdtime|format_date('long') %}
@see http://agileadam.com/2017/08/drupal-8-formatting-a-date-field-in-twig/
Use Twig date filter + a defined Drupal date format
{{ node.field_blog_date.value|date('U')|format_date('short_mdyyyy') }}
Use Twig date filter
{{ node.field_blog_date.value|date('n/j/Y') }}
Set variables in a translated twig variable
<p class="submitted">{{ "Submitted by !author on @date"|t({ '!author': author, '@date': date }) }}</p>
or
  {% set front_uri = path('<front>') %}
  {% set search_uri = path('view.solr_search_content.page_1') %}
  <p>{% trans %}Return to the <a href="{{ front_uri }}">homepage</a> or <a href="{{ search_uri }}">search articles</a>.{% endtrans %}</p>
  <p>{{ 'Return to the <a href="@front">homepage</a> or <a href="@search">search articles</a>.'|t({'@front': front_uri, '@search': search_uri}) }}</p>

or
{% set  url_1 = path('entity.node.canonical', {'node': 1050}) %}
{% set  url_2 = path('entity.node.canonical', {'node': 2010}) %}
{% trans %}I will have <a href="{{ url_1 }}">one link</a> and <a href="{{ url_2 }}">a second link.</a>{% endtrans %}

@see - more on twig translation https://getlevelten.com/blog/mark-carver/drupal-8-twig-templates-and-translations
Create a link
<a href="{{ path('contact.site_page') }}">{{ 'Contact'|t }}</a>    
<a href="{{ url('contact.site_page') }}">{{ 'Contact'|t }}</a>
{{ link('Contact'|t, 'base:contact', { 'class':[] }) }}

@see - https://drupal.stackexchange.com/a/208107/30331
Render a field to use it eg, in a translated string
{% set number = "Duo @number"|t({ '@number': number|render|striptags }) %}
@see https://www.drupal.org/project/drupal/issues/2728915#comment-11208967
Loop through child elements in Twig like Element::children()
! First @see https://www.drupal.org/node/2776307
And https://www.drupal.org/project/twig_extender
{% for key, child in parent if key|first != '#' %}
  {{ child }}
{% endfor %}

@see https://drupal.stackexchange.com/questions/174742/loop-through-child-elements-in-twig-like-elementchildren/174743
or
{% for key, item in items %}
  {% if key matches '/^\\d+$/' %}
    {{ item }}
  {% endif %}
{% endfor %}

Be carreful, this bypasses theme and will print without template and any html field wrappers
@see https://www.drupal.org/forum/support/theme-development/2015-12-16/entity-reference-values-in-twig-template#comment-10900706
Merge arrays
That synthax avoid errors if classes is initialy empty.
{% set classes = { 'class' : 'teaser' }|merge({ (classes) : classes }) %}
<article class="{{ classes|join(' ') }}" role="article">

Override custom layout templates (eg for a specific node)

Be carreful to set

et_twocols_hero:
  class: '\Drupal\ds\Plugin\DsLayout'


Also name the template as the machine name otherwise suggestions provided by DS will not follow the same convention bu the one from machine name then Entity, bundle, view mode

et_twocols_hero:
  template: templates/et-twocols-hero

Provide splited views More link and title vars
/**
 * Implements template_preprocess_views_view()
 * @param array $variables
 */
function hook_preprocess_views_view(&$variables){
  $view = $variables['view'];

  $variables['more_url'] = $variables['more']['#url'];
  $variables['more_text'] = $variables['more']["#title"];

  // @todo see usage of `title`, maybe combined with twig if on default template
  $variables['custom_title'] = [
    '#markup' => $view->getTitle(),
  ];
}

Provide block classes from id

plugin_id : unique identifier provided for all blocks (duplicated one, displayed by context module)
elements['#id'] : unique identifier depending on block id defined via block layout UI, NULL is returned by context module

{%
  set classes = [
    'block-' ~ plugin_id|clean_class,
    'block--' ~ (elements['#id'] ? elements['#id']|clean_class),
  ]
%}

Provide Custom block bundle templates / or classes (block types from custom block library)
use \Drupal\block_content\BlockContentInterface;

/**
 * Implements hook_theme_suggestions_block_alter().
 */
function hops_theme_suggestions_block_alter(array &$suggestions, array $variables) {
  $content = $variables['elements']['content'];
  if (isset($content['#block_content']) and $content['#block_content'] instanceof BlockContentInterface) {
    $bundle = $content['#block_content']->bundle();
    $view_mode = $content['#view_mode'];
    $suggestions[] = 'block__' . $bundle;
    $suggestions[] = 'block__' . $view_mode;
    $suggestions[] = 'block__' . $bundle . '__' . $view_mode;
  }
}

Display a block entity reference field
{% block content %}
  {% set node_1_teaser = content.field_node_reference.0|merge({'#view_mode': 'compact'}) %}
  {% set node_2_teaser = content.field_node_reference.1|merge({'#view_mode': 'compact'}) %}
  {{ node_1_teaser }}
  <a href="{{ path('entity.node.canonical', {'node': content.field_node_reference.0['#node'].id}) }}">{{ 'Learn more'|t }}</a>
  {{ node_2_teaser }}
  <a href="{{ path('entity.node.canonical', {'node': content.field_node_reference.1['#node'].id}) }}">{{ 'Learn more'|t }}</a>
{% endblock %}

Render referenced entity field as text
Example here for a referenced paragraph but could work with a node with tab['#node'].
{% for key, tab in content.field_reference_tab if key|first != '#' %}
  {% set body = {
    '#type': 'processed_text',
    '#text': tab['#paragraph'].get('field_body').getValue.0.value,
    '#format': tab['#paragraph'].get('field_body').getValue.0.format,
  } %}
  {{ body }}
{% endfor %}