Code

Select:

    $con = \Drupal\Core\Database\Database::getConnection();

    $query = $con->select('table_name', 't')

        ->fields('t', ['field_1', 'field_2']);



Cache configuration of a renderer array (Just an exaple)

What is drupal behaviors ?

Drupal behaviors allow to execute javascpts in particular context and / or pass data from drupal to client side java script.

This system allow you to invalidate drupal cache using a 'tag'

Exapples:

Example 1. Basic inline template

    $output[] = [

      '#type' => 'inline_template',

      '#template' => '{{ yourvar }}',

      '#context' => [



You can't change the body of this block fron the user interface. But you can do that using a small custom module using hook_block_view_alter().

You can find any entity using Drupal 8 EntityQuery System.

Example:

1. in yourmodule.links.menu.yml

yourmodule.test:

  title: Test

  parent: system.admin_config_development

  route_name: yourmodule.test

Site URL

1. Go to Administration > Configuration > Development > Performance

 (/admin/config/development/performance)

2. Click on "Clear all caches"

Example 1, with FieldPluginBase (\Drupal\views\Plugin\views\field\FieldPluginBase)