woutersf

<?php
//The submit handler function:
public function reImportAllFiles(array &$form, FormStateInterface $form_state){
    $form_state->setRedirect('vrt_dram.batch', array());
}

woutersf

<?php

//use...

class MySettingsForm extends ConfigFormBase {

  public function buildForm(array $form, FormStateInterface $form_state) {
    //The form
    //..

woutersf

<?php

//If anonymous
if (\Drupal::currentUser()->isAnonymous()) {
  // Do something..
}

//if user has role
$roles = \Drupal::currentUser()->getRoles();
if(!in_array("administrator", $roles)) {

woutersf

<?php

///////////////////JSON

//How to render Json from Drupal 8
$response = new Response();
$response->setContent(json_encode($mydata));
$response->headers->set('Content-Type', 'application/json');
return $response;

woutersf

<?php

//For nodes.
if ($node = \Drupal::routeMatch()->getParameter('node')) {
  if ($node->getType() == 'article') { // Test the node type.
    $is_video = $node->get('field_is_video')->value; // Get the field value of on of the node fields.
    $class_suffix = $is_video ? 'video' : 'no-video';
    $vars['attributes']['class'][] = Html::getClass($node->getType() . '--' . $class_suffix); //Add Class to the variables.
  }
}

woutersf

<?php
//If is frontpage
$on_frontpage = \Drupal::service('path.matcher')->isFrontPage();

//Match canonical route
$route_match = \Drupal::routeMatch();
if ($route_match->getRouteName() == 'entity.node.canonical') {
  // Do something..
}