Drupal-Common-Snippets.php

// Is the current route/path the front page?
if ($is_front = \Drupal::service('path.matcher')->isFrontPage()) {}

// Need to know what the current page's requested path was, as opposed to the route? You can do this:
$current_uri = \Drupal::request()->getRequestUri();

// Need to redirect to a specific page?
use Drupal\Core\Controller\ControllerBase;

class MyControllerClass extends ControllerBase {

  public function foo() {
    //...
    return $this->redirect('user.page');
  }
}

// In Drupal 8, if you need to create links on the fly, utilize the Link class

$link = \Drupal\Core\Link::fromTextAndUrl($text, $url);

// Query for some entities with the entity query service.
$query = \Drupal::entityQuery('node')
  ->condition('status', 1)
  ->condition('type', 'article')
  ->range(0, 10)
  ->sort('created', 'DESC');

$nids = $query->execute();

// If you need to load the actual entities, you can do so a number of ways:
$node = entity_load_multiple('node', $nids);

$nodes = \Drupal::entityTypeManager()->getStorage('node')->loadMultiple($nids);

$node = \Drupal::entityTypeManager()->getStorage('node')->load($nid);

// Link to an entity using the entity's link method.
$author_link = $user->toLink();

// Do the same thing, but customize the link text.
$author_link = $user->toLink('Some Custom Text');

// Given a node object, here's how to determine its type:
$type = $node->getType();

// To get the full user entity of the node's author:
$author = $node->getOwner();

// To get the raw ID of the author of a node:
$author_id = $node->getOwnerId();

// Create an instance of an image using a specific image style, given a path to a file.
$style = \Drupal\image\Entity\ImageStyle::load('yourStyle_image');
$img_path = $user->field_profile_some_image->entity->getFileUri();
$img_style_url = $style->buildUrl($img_path);


// Get $_POST and $_GET parameters

// Post
$name = \Drupal::request()->request->get('name'); // form param

// Get
$query = \Drupal::request()->query->get('name');