drupal tag filter ajax content code example

Example: drupal tag filter ajax content

<?php

/**
 * @file
 * Module file for Popolo Custom.
 */

/**
 * Implements hook_form_alter().
 */
function popolo_custom_form_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id){
    
  // Apply the form_alter to a specific form #id
  // the form #id can be found through inspecting the markup.
  if($form['#id'] == 'views-exposed-form-filter-articles-page-1') {
  
    // Include js and css, which was defined in libraries.yml.
    $form['#attached']['library'][] = 'popolo_custom/popolo_custom.enable';	
    $form['#attached']['library'][] = 'popolo_custom/popolo_custom.forms';
	
    // Extract the options from the Views Exposed Filter <select>-list. 
    $links = $form['field_tags_target_id']['#options'];

    // Iterate over the options ($links) to build an array ($pop_array) of links.
    $i = 0; // Initiate counter/index
    $pop_array = array();
	foreach ($links as $tid => $term_name) {
		if ($tid == 'All') {
			$pop_array[$i]['#markup'] = '<span class="filter-tab"><a href="" class="active" id="' . $tid . '">' . $term_name . '</a></span>';
		}
		else {
			$pop_array[$i]['#markup'] = '<span class="filter-tab"><a href="" id="' . $tid . '">' . $term_name . '</a></span>';
		}
		$i++; // Increase counter/index
	} 
	
	// Create the item-list the form should render.
	$form['links'] = [
	  '#theme' => 'item_list',
	  '#items' => $pop_array,
	  '#attributes' => ['class' => ['pop-list']],
    ]; 
  } 
}