How do I get the current node ID?

Question

In Drupal 7, if I wanted to get the node id of the currently displayed node (e.g. node/145) I could get it with the arg() function. In this case, arg(1) would return 145.

How can I achieve the same in Drupal 8?

Answer 1

The parameter will have been upcasted from nid to full node object by the time you get access to it, so:

$node = \Drupal::routeMatch()->getParameter('node');
if ($node instanceof \Drupal\node\NodeInterface) {
  // You can get nid and anything else you need from the node object.
  $nid = $node->id();
}

See the change record for more information.

Answer 2

It is correct to use \Drupal::routeMatch()->getParameter('node'). If you just need the node ID, you can use \Drupal::routeMatch()->getRawParameter('node').

Answer 3

Note on the node preview page, the following doesn't work:

$node = \Drupal::routeMatch()->getParameter('node');
$nid = $node->id();

For the node preview page, you have to load the node this way:

$node = \Drupal::routeMatch()->getParameter('node_preview');
$nid = $node->id();

How to load node object in node preview page?

Answer 4

if you are using or creating custom block then you have to follow this code to get current url node id.

// add libraries
use Drupal\Core\Cache\Cache;  

// code to get nid

$node = \Drupal::routeMatch()->getParameter('node');
  $node->id()  // get current node id (current url node id)


// for cache

public function getCacheTags() {
  //With this when your node change your block will rebuild
  if ($node = \Drupal::routeMatch()->getParameter('node')) {
  //if there is node add its cachetag
    return Cache::mergeTags(parent::getCacheTags(), array('node:' . $node->id()));
  } else {
    //Return default tags instead.
    return parent::getCacheTags();
  }
}

public function getCacheContexts() {
  //if you depends on \Drupal::routeMatch()
  //you must set context of this block with 'route' context tag.
  //Every new route this block will rebuild
  return Cache::mergeContexts(parent::getCacheContexts(), array('route'));
}

Answer 5

By using Service,

    use Drupal\Core\Routing\RouteMatchInterface;

/**
 * Provides a 'UtilitiesDataService' service.
 */
class MyClass {
 

  /**
   * The route match.
   *
   * @var \Drupal\Core\Routing\RouteMatchInterface
   */
  protected $routeMatch;

  /**
   * Constructs a new service.
   *
   * @param \Drupal\Core\Routing\RouteMatchInterface $route_match
   *   The route match.
   */
  public function __construct(RouteMatchInterface $route_match) {

    $this->routeMatch = $route_match;
  }

  public function getNodeId(){
    $nid = $this->routeMatch->getParameter('node')->id();
  }
}

In services.yml file,

services:
   my_module.get_data_service:
    class: Drupal\my_module\MyClass
    arguments: ['@current_route_match']

Answer 6

Blocks are context aware and you should be using them. This will allow using the blocks in places where the route itself doesn't have a node but some subsystem provides the context anyways.

Example from core:

/**
 * Provides a 'Node Context Test' block.
 *
 * @Block(
 *   id = "node_block_test_context",
 *   label = @Translation("Node Context Test"),
 *   context_definitions = {
 *     "node" = @ContextDefinition("entity:node", label = @Translation("Node"))
 *   }
 * )
 */
class NodeContextTestBlock extends BlockBase {

  public function build() {
    /** @var \Drupal\node\NodeInterface $node */
    $node = $this->getContextValue('node');

You can also see how easy it is to get the node. The test this block is used for is instructional: it tests whether the block appears on the preview page. This is not doable with the route match approach as the /node/preview/{node_preview}/{view_mode_id} route doesn't contain a node at all.

This will also make the node context required so there's no need to check whether there is a node at all. It's possible to make the node optional, of course:

 *     "node" = @ContextDefinition("entity:node", label = @Translation("Node"), required = FALSE)

the order of options after the first argument does not matter.