How to log error message in drupal

How to log our **own error messages**(for ex: error due to invalid user date entry) which is generated in *php* program to **drupal error log**.

You can use the [`watchdog` function][1] :

watchdog($type, $message, $variables = array(), $severity = WATCHDOG_NOTICE, $link = NULL)

Quoting the manual, the parameters are :

- `$type` The category to which this message belongs.
- `$message` The message to store in the log.
- `$variables` Array of variables to replace in the message on display or NULL if message is already translated or not possible to translate.
- `$severity` The severity of the message, as per RFC 3164
- `$link` A link to associate with the message.

And the error levels can be found on the page of [`watchdog_severity_levels`][2]. For an error, you'll most probably use `WATCHDOG_ERROR`, or maybe even something more "critical", depending on the kind of error.


[1]:

[To see links please register here]

[2]:

[To see links please register here]

Watchdog is the way to go for a production system no doubt but during debugging I find the `drupal_set_message` function useful.

It outputs the message to the screen where the 'Operation Successful'-type messages are normally displayed (so make sure you remove them before making the site Live).

[To see links please register here]

1) Indeed, watchdog is a standard way to record own PHP errors.

2) Alternatively, if you need to immediately see error messages while debugging your Drupal pages, you may want to see them logged/printed right at the related page - in FireBug console.
Sometimes is this very convenient when you can see page-related just-in-time logs.
This requires - [Devel][1] module, [Firebug][2] extension to FireFox and possibly [Firephp][3].

You can use the dfb() function to write log messages directly to the general Firebug console.

dfb($input, $label = NULL)

If you want to keep your Drupal-related log messages out of the normal Firebug console, you can write messages to the [Drupal for Firebug][4] log with the firep() function:

firep($item, $optional_title)


[1]:

[To see links please register here]

[2]:

[To see links please register here]

[3]:

[To see links please register here]

[4]:

[To see links please register here]

[padding]: padding_for_edit

In drupal 7 we can log message by following method:

drupal watchdog function we can use to log message in database , make sure we have enabled optional core module for Database Logging at /admin/build/modules.



watchdog($type, $message, $variables = array(), $severity = WATCHDOG_NOTICE, $link = NULL)



**$type:**
The category to which this message belongs , Example: PHP,cron.., we can filter message by type.

**$message :**
The message to store in the log,Example: 'The following module is missing from the file system: security_review'

**$variables :**
Array of variables to replace in the message on display or NULL if message is already translated or not possible to translate.
to make message translated , do not pass dynamic value pass variables in the message should be added by using placeholder strings.

**Example:**
watchdog('cg_volunteer', 'cg in form_alter %formly', array('%formly' => $form['#id']), WATCHDOG_NOTICE, $link = NULL);

**$severity**
The severity of the message,logs can be filter by severity as per RFC 3164. Possible values are WATCHDOG_ERROR, WATCHDOG_WARNING, etc.
For more example see

[To see links please register here]

**$link**:
A link to associate with the message.

**Example**

// for logs notices

watchdog('my_module', $message, array());

// for Loging Error

watchdog('my_module', $message, array(), WATCHDOG_ERROR);

**In drupal 8 we used following method:**

// For Logs a notice.

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

// For Logs an error.

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

// For Alert, action must be taken immediately.


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

// For Critical message.

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

// For Debug-level messages.

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

//For Emergency, system is unusable.

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

//For Warning

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

//For Informational messages.

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

Also for translate we should not use t() function.

\Drupal::logger('my_module')->alert('Message from @module: @message.', [
'@module' => $module,
'@message' => $message,
]);

this will be translated on run time.

**Example :**

\Drupal::logger('content_entity_example')->notice('@type: deleted %title.',
array(
'@type' => $this->entity->bundle(),
'%title' => $this->entity->label(),
));

Both `watchdog` for D7 & `\Drupal::logger` for D8 will write log in `watchdog` table (in your database), and with **HUGE data logged**, you can imagine performance impact.

You can use `error_log` php function to do it (see [PHP manual][1]).


error_log("Your message", 3, "/path/to/your/log/file.log");

> You need to have permission to write in your log file (`/path/to/your/log/file.log`)

[tag:drupal-8][tag:drupal][tag:php][tag:log]

[1]:

[To see links please register here]

// Get logger factory.
$logger = \Drupal::service('logger.factory');

// Log a message with dynamic variables.
$nodeType = 'Article';
$userName = 'Admin';
$logger->get($moduleName)->notice('A new "@nodeType" created by %userName.', [
'@nodeType' => $nodeType,
'%userName' => $userName,
]);

[Source][1]


[1]:

[To see links please register here]

Drupal 8+

// Logs a notice
\Drupal::logger('my_module')->notice($message);
// Logs an error
\Drupal::logger('my_module')->error($message);

See more examples at [How to Log Messages in Drupal 8][1].


[1]:

[To see links please register here]