Create custom twig templates for custom module in Drupal 8

Example 1

Create mymodule.module file

/**
 * Implements hook_theme() to add the template definition.
 **/
function mymodule_theme($existing, $type, $theme, $path) {
    return array(
        'mymodule_template' => array(
            'variables' => array('test_var' => NULL),
        ),
    );
}

Create src/Controller/MyModuleController.php file

<?php
namespace Drupal\mymodule\Controller;

use Drupal\Core\Controller\ControllerBase;

class MyModuleController extends ControllerBase {
    public function content() {

        return array(
            '#theme' => 'mymodule_template',
            '#test_var' => $this->t('Test Value'),
        );

    }
}

Create in the templates folder the mymodule-template.html.twig file

<p> This is the lotus template with a value of {{ test_var }} </p>

Example 2

I will use the two examples below to show you how to add custom template to our codimth_controller module.

https://codimth.com/blog/drupal8-get-user-list-role-programmatically

https://codimth.com/blog/drupal-8-create-custom-page-programmatically

Create  hook_theme() in codimth_controller.module 

<?php

/**
 * @param $existing
 * @param $type
 * @param $theme
 * @param $path
 * @return array
 */
function codimth_controller_theme($existing, $type, $theme, $path) {
    return [
        'codimth' => [
            'variables' => ['users' => NULL],
        ],
    ];
}

Create src/Controller/CodimthController.php file

<?php

namespace Drupal\codimth_controller\Controller;

use Drupal\Core\Controller\ControllerBase;
use Drupal\user\Entity\User;

class CodimthController extends ControllerBase
{
    public function index()
    {
        $userlist = [];
        $ids = \Drupal::entityQuery('user')
            ->condition('status', 1)
            ->condition('roles', 'administrator')
            ->execute();
        $users = User::loadMultiple($ids);
        foreach ($users as $user) {
            $username = $user->get('name')->getString();
            $mail = $user->get('mail')->getString();
            $userlist[] = ['mail' => $mail, 'username' => $username];
        }

        return array(
            '#theme' => 'codimth',
            '#users' => $userlist
        );
    }
}

Create twig template templates/codimth.html.twig 

<p>Test twig template!</p>

{% for user in users %}
    <p>{{ user.mail }}: {{ user.username }}</p>
{% endfor %}

Next steps

• Clear your Drupal 8 caches. To do this I use this Drush command: drush cr if you don’t currently use Drush, I highly recommend using it, or the Drupal Console.
• Now, go back to your site, and you should be able to see the new custom template you have just created.
• I hope you found this article useful. let me know if you have any questions and I’ll be happy to answer them.
• This code can be found and downloaded from https://github.com/codimth/codimth_controller.