How can I log(watchdog)?

Question

In D7 is used to log using Watchdog function. In D8, I see its gone and I should use something called the logging API.

What I a trying to do:

1. I have created a menu/route, mysite.com/logmessage
2. When user opens that url in browser, I want to log "hello" to the dblog.

Where should I register the service that D8 documentation says to do? Is it in the services.yml file in sites/default folder?

Can I just load the said class in my controller/module file and call the function for logging? Or should I explicitly extend the class first in my module before using the function?

Answer 1

Can I just load the said class in my controller/module file and call the function for logging?

Yes; well, by "load the said class" you actually mean "get or inject an instance of the service class" in this context, but yes.

should I explicitly extend the class first in my module before using the function?

Not unless you need functionality that the existing service doesn't provide.

In non DI code use:

\Drupal::logger('my_module')->info('Info');

In DI code, inject the service and use:

$this->logger->info('Info');

Answer 2

There are many different types of logging, all called the same way as per the documentation:

\Drupal::logger('my_module')->alert($message);

\Drupal::logger('my_module')->info($message);

\Drupal::logger('my_module')->debug($message);

Just call this code anywhere in your module, if you want to register logmessage as a path you'll need to create my_module.routing.yml, etc.