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Logging ​

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Quick log to watchdog ​

With the Database Logging (dblog) module enabled, you can easily log messages to the database log (watchdog table)

php
//Class with method name 
$method = __METHOD__; 

// Function name only.
$function = __FUNCTION__; 

// Function name, filename, line number.
$str =  __FUNCTION__." in ".__FILE__." at ".__LINE__;

\Drupal::logger('test')->info("method = $method");
\Drupal::logger('test')->info("Something goofed up at $str");
\Drupal::logger('test')->debug("Something goofed up at $str");
\Drupal::logger('test')->critical("Something goofed up at $str");

\Drupal::service('logger.factory')->get('test')->error('This is my error message');

The parameter "test" used above is typically the module name. It is stored in the "type" field.

You can call difference methods such as info, warning etc. which populate the severity field with an integer indicating the severity of the issue.

The methods are defined in Drupal\Core\Logger\RfcLoggerTrait:

  • emergency($message, $context)

  • alert($message, $context)

  • critical($message, $context)

  • error($message, $context)

  • warning($message, $context)

  • notice($message, $context)

  • info($message, $context)

  • debug($message, $context)

More at https://www.drupal.org/docs/8/api/logging-api/overview

Log an email notification was sent to the the email address for the site. ​

php
$email_config = \Drupal::config('system.site');
$to = $email_config->get('mail');
// Display message to screen.
$messenger->addMessage("sent a message to $to");
// Log it.
\Drupal::logger('DIR')->info("Email notification send to $to succeeded");

Incidentally, calling \Drupal::logger like this

php
\Drupal::logger('my_module')->error('This is my error message');

actually does this under the covers:

php
\Drupal::service('logger.factory')->get('my_module')->error('This is my error message');

Logging from a service using dependency injection ​

From a controller e.g. WebsphereAddress.php

In the websphere_commerce.services.yml specify the @logger.factory to be passed into the constructor.

yaml
services:
  websphere_commerce.address:
    class: Drupal\websphere_commerce\WebSphereAddressService
    arguments: ['@config.factory', '@logger.factory']

In the WebsphereAddress.php file specify use statements:

php
use Drupal\Core\Logger\LoggerChannelFactory;
use Drupal\Core\Logger\LoggerChannelFactoryInterface;

Create a protected var to store the logger service:

php
/**
 * Logger factory.
 *
 * @var \Drupal\Core\Logger\LoggerChannelFactoryInterface
 */
protected $logger;

Here is the constructor:

php
/**
 * WebsphereAddress constructor.
 *
 * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
 *   Config factory.
 * @param \Drupal\Core\Logger\LoggerChannelFactoryInterface $channel_factory
 *   Logger factory.
 */
public function __construct(ConfigFactoryInterface $config_factory, LoggerChannelFactoryInterface $channel_factory) {
  $this->websphereConfig = $config_factory->get('websphere_commerce.api_settings');
  $this->logger = $channel_factory;
}

Log errors.

php
if ($response['status'] == API_ERROR) {
  $this->logger->get('websphere_commerce')->alert("Error saving Shipping info to Websphere.");
}

Another example using the logging via dependency injection ​

From the excellent folks at symfonycasts.com who have a sweet Drupal 8 course which is still relevant and worth checking out.

In your dino_roar.services.yml file, add the listener and specify the arguments of ['@logger.factory']

Note. You can find the factory info with Drupal console:

$ drupal debug:container | grep log

one of the results specifies the factory which you can use below:

logger.factory               Drupal\\Core\\Logger\\LoggerChannelFactory

or with Drush and devel

$ drush dcs log

- logger.dblog
- logger.drupaltodrush
- logger.factory

So dino_roar.dino_listener will pass the logger.factory service to your DinoListener class.

yaml
dino_roar.dino_listener:
  class: Drupal\dino_roar\Jurassic\DinoListener
  arguments: ['@logger.factory']
  tags:
    - {name: event_subscriber}

in your DinoListener.php specify a constructor argument of LoggerChannelFactoryInterface and store it.

php
namespace Drupal\dino_roar\Jurassic;


use Drupal\Core\Logger\LoggerChannelFactoryInterface;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\HttpKernel\Event\GetResponseEvent;
use Symfony\Component\HttpKernel\KernelEvents;

class DinoListener implements EventSubscriberInterface {

  /**
   * @var \Drupal\Core\Logger\LoggerChannelFactoryInterface
   */
  private $loggerChannelFactory;

  public function __construct(LoggerChannelFactoryInterface $loggerChannelFactory) {

    $this->loggerChannelFactory = $loggerChannelFactory;
  }

  public function onKernelRequest(GetResponseEvent $event) {
    $request = $event->getRequest();
    $shouldRoar = $request->query->get('roar');
    if ($shouldRoar) {
      $this->loggerChannelFactory->get('default')
        ->debug('Roar Requested ROOOOAAAARRR!');
    }
  }

  public static function getSubscribedEvents() {
    return [
      KernelEvents::REQUEST => 'onKernelRequest',
    ];
  }
}

Logging exceptions from a try catch block ​

In this controller, the try block calls the test() method which throws an exception. The catch block catches the exception and logs the message (and for fun displays a message in the notification area also.)

php
  public function build() {

    try {
      $this->test();
    }
    catch (\Exception $e) {
      watchdog_exception('nuts_connect', $e);
      $messenger->addMessage("No, I got caught!");
    }

    $build['content'] = [

      '#type' => 'item',
      '#markup' => $str,
    ];

    return $build;
  }

  function test() {
    throw new \Exception("blah", 7);
  }

Display a message in the notification area ​

You can display a message with:

php
$messenger = \Drupal::messenger();
$messenger->addMessage("a message");
$messenger->addError("error message");

Or

php
\Drupal::messenger()->addError("migration failed");

\Drupal::messenger()->addMessage($message, $type, $repeat);

Use $repeat = FALSE to suppress duplicate messages.

Specify MessengerInterface::TYPE_STATUS,MessengerInterface::TYPE_WARNING, or MessengerInterface::TYPE_ERROR to indicate the severity.

Don't forget

php
use Drupal\Core\Messenger\MessengerInterface;

Note. addMessage() adds class="messages messages--status" to the div surrounding your message while addError adds class="messages messages--status" . Use these classes to format the message appropriately.

When you need to display a message in a form, use the $this->messenger() that is provided by the Drupal\Core\Messenger\MessengerTrait;

php
$this->messenger()->addStatus($this->t('Running in Destructive Mode - Changes ARE committed to the database!'));

e.g.

php
\Drupal::messenger()->addMessage('Program pending, please assign team and initialize. ', MessengerInterface::TYPE_WARNING);

This example builds a $helpdesk_url, calls a sendMail() function and then depending on the return value $results it displays a message or error with a built in link in the notification area:

php
    $helpdesk_url = Url::fromUri('https://helpdesk.abc..gov/helpme');
    $helpdesk_url->setOptions(['attributes' => ['target' => '_blank']]);
    $helpdesk_link = \Drupal::service('link_generator')->generate('please submit a help ticket here', $helpdesk_url);
    $results = $general_utility->sendEmail([$email_to], $from_email, $subject, $message_body );
    $result = reset($results);
    if ($result['status'] == 'success') {
      $render_array = [
        '#type' => 'markup',
        '#markup' => $this->t('The @submission_type has been created. Should you need to edit your submission, @link. Sent confirmation email to @email_to', [
          '@submission_type' => $values['submission_type'],
          '@link' => $helpdesk_link,
          '@email_to' => $email_to,
        ]),
      ];
      \Drupal::messenger()->addMessage($render_array);
    }
    else {
      $render_array = [
        '#type' => 'markup',
        '#markup' => $this->t('The @submission_type has been created. Should you need to edit your submission, @link. Failed to send confirmation email to @email_to', [
          '@submission_type' => $values['submission_type'],
          '@link' => $helpdesk_link,
          '@email_to' => $email_to,
        ]),
      ];
      \Drupal::messenger()->addError($render_array);
    }

Display a message to an anonymous user after redirect ​

From a slack discussion in the Drupal #Support Slack channel, here is an example of how to display a message to an anonymous user after a redirect. Be aware that this may work for the first user (without the \Drupal::service('session')->save() call, but may fail on subsequent attempts. The session service is used to store the messages in the session.

php
    // Set a message to inform the user
    \Drupal::messenger()->addMessage(t('Thank you for applying for an account. Your account is currently pending approval by the site administrator.<br />In the meantime, a welcome message with further instructions has been sent to your email address.'));

    // Store the messages in the session
    \Drupal::service('session')->save();

    // Perform redirection to the front page
    $url = Url::fromRoute('<front>')->toString();
    $response = new RedirectResponse($url);
    $response->send();
    exit;

Display a variable while debugging ​

You can use var_dump and print_r but sometimes it is difficult to see where they display.

php
$is_front = \Drupal::service('path.matcher')->isFrontPage();
$is_front = $is_front == TRUE ? "YEP" : "NOPE";
$messenger->addMessage("is_front = $is_front");
var_dump($is_front);
print_r($is_front);

Displaying var_dump in Drupal

Reference ​