Getting form variables data into twig templates

Question

I want to pass an array and a form to a template file, using this code.

public function buildForm(array $form, FormStateInterface $form_state) {
  $form['job_locations'] = $job_locations;
  $form['#theme'] = 'search_form';
  $form['#method'] = 'get';
  // Omissis
  return  $form;
}

The value of $job_locations is the following.

Array(
  [0] => Array(
    [city] => Singapore
    [count] => 5
  )
  [1] => Array(
    [city] => Toronto
    [count] => 3
  )
)

The content of the template file is the following.

{% for location in form.job_locations %}
  {% if location.city  %}
    <li data-original-index="0">
      <a tabindex="0" class="location-list-item" data-tokens="null" role="option" aria-disabled="false" aria-selected="false">
        <span class="text">{{ location.city }}</span>
      </a>
    </li>
  {% endif %}
{% endfor %}

Everything is shown correctly, but the code I am using causes these errors.

User error: "count" is an invalid render array key in Drupal\Core\Render\Element::children()
User error: "city" is an invalid render array key in Drupal\Core\Render\Element::children()

How can I avoid to get these errors?

Answer 1

Three possible solutions:

1. Valid render array

   You get a valid render array by putting the content of city and count in #markup elements:

     'city' => [
       '#markup' => 'Singapore',
   

2. Form variable with a #

   Or start the variable name with a hash, so that it is no longer considered to be a form element which needs to be rendered:

   $form['#job_locations'] = ...
   

   Twig:

   {% for location in form['#job_locations'] %}
     ...
   {% endfor %}
   

3. Separate template

   Or create a custom template with a variable for the locations array to theme the list separately from the form:

   $form['job_locations'] = [
     '#theme' => 'job_location_list',
     '#locations' => $job_locations,
   ];