How can I retrieve the current node ID on a custom route?

Question

I have a new route and the yml file looks like this:

rsvplist.form:
  path: '/rsvplist'
  defaults:
    _form: '\Drupal\rsvplist\Form\RSVPForm'
    _title: 'RSVP to this Event'
  requirements:
    _permission: 'access content'

From the module root directory, I have src/Form/RSVPForm.php, and inside is where I have the build form function that looks like the following:

public function buildForm(array $form, FormStateInterface $form_state) {
    $node = \Drupal::routeMatch()->getParameter('node');
    $nid = $node->nid->value;

    $form['email'] = [
        '#title' => t('Email Address'),
        '#type' => 'textfield',
        '#size' => 25,
        '#description' => t('We will send updates to the email you provide.'),
        '#required' => TRUE,
    ];

    $form['submit'] = [
        '#type' => 'submit',
        '#value' => t('RSVP'),
    ];

    return $form;
}

When I clear the site cache and refresh the page: mylocal.com/rsvplist, I see the following error:

Notice: Trying to get property 'nid' of non-object

I initially used the following code to get the node

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

If I change the last piece of code to this:

$nid = $node->id();

I see the following error:

Error: Call to a member function id() on null

How can I get the node id when am on the new route?

Reference here

Answer 1

Your route doesn't have a parameter called node, so therefore $node is null.

In order to make node available as a parameter you have to be on a route that has node as a parameter.

So to add the node parameter to your route, you can do like this:

rsvplist.form:
  path: '/rsvplist/{node}'
  defaults:
    _form: '\Drupal\rsvplist\Form\RSVPForm'
    _title: 'RSVP to this Event'
  requirements:
    _permission: 'access content'
    _entity_access: 'node.view'
    node: \d+

And then you can add the $node parameter to your buildForm method, like this:

public function buildForm(array $form, FormStateInterface $form_state, NodeInterface $node = NULL) {
  // Your form.
}

Since I added node: \d+ to your form, $node is now the loaded entity in the buildForm method.

Answer 2

You can try code

rsvplist.form:
  path: '/rsvplist/{nid}'
  ....


use Drupal\node\NodeInterface;
....
$nid= \Drupal::routeMatch()->getParameter('nid');
$node = Node::load($nid);