I'm trying to connect to a LDAP server using Laravel. It is important to say that I'm using the PHP functions ldap_connect and ldap_bind instead of using a package to handle it.
The point is that when I provide wrong user and password, the ldap_bind function gives to us a PHP warning. I'm OK with this warning and, as is in the documentation, the function returns false when the bind does not occur.
But, Laravel is throwing an exception when this warning is triggered. This is not an exception, Laravel should not throw an exception and I wouldn't like to handle this as an exception; I just have to build an if condition that will return a message to the user.
Does Laravel catch all warnings as an Exception?
This is the intended behavior for Laravel. Laravel will turn any error into an ErrorException instance. Here's the bootstrap() method inside the Illuminate/Foundation/Bootstrap/HandleExceptions.php class.
public function bootstrap(Application $app)
{
$this->app = $app;
error_reporting(-1);
set_error_handler([$this, 'handleError']);
set_exception_handler([$this, 'handleException']);
register_shutdown_function([$this, 'handleShutdown']);
if (! $app->environment('testing')) {
ini_set('display_errors', 'Off');
}
}
The error_reporting(-1); will set PHP to report all errors (read more here).
While this part of code:
set_error_handler([$this, 'handleError']);
Will set a custom error handler. If you check the handleError() method, it's pretty clear that Laravel will turn any error into an ErrorException instance.
public function handleError($level, $message, $file = '', $line = 0, $context = [])
{
if (error_reporting() & $level) {
throw new ErrorException($message, 0, $level, $file, $line);
}
}
Read more about user-defined error handler here.
Hope this clear things up. :)
Not sure exactly the reason because I didn't write it but I assume having it work this way makes logging much easier.
Warnings get logged in php's error log but it's not possible to pass additional information along with it as context.
If that warning gets turned into an exception though, then you can pass the exception to the logger as well as other information such as the route which was hit, the request variables, etc... and log everything together. You also get to dictate the severity of the issue by designating it as log, debug, info, notice, warning, error, critical, alert, and emergency and through monolog, handle each of those as you see fit. This creates a log which is much easier to read and makes your code much easier to debug.
Additionally, as others have pointed out, it also allows you to do your work in try catch blocks which I believe also creates neater and cleaner code than trying to check if some variable === false
Shorter explanation:
I've realised I posted this as a really long-winded explanation - I've left the previous explanation below but added a shorter summary.
In my CodeIgniter application, the error reporting level is set to 0. If I try to reference an undefined index (for example) in a controller or view, no error is outputted which is as expected.
However, I have a library, which loads in a third party class (NuSoap).
If the NuSoap class experiences an error - it will still output the error in my application.
Errors will also be outputted if the error is encountered in the library file itself.
Why is this? If it's being loaded in through CodeIgniter, through a library surely it should inherit the error reporting level?
Previous (long-winded) explanation:
I'm having some trouble understanding how the error reporting is working throughout my CodeIgniter application.
In index.php my error reporting is set up as follows:
if (defined('ENVIRONMENT'))
{
switch (ENVIRONMENT)
{
case 'development':
error_reporting(E_ALL);
break;
case 'testing':
case 'production':
error_reporting(0);
break;
default:
exit('The application environment is not set correctly.');
}
}
I'm using the production environment, so my expected output when an error/warning/notice is due would be that nothing is displayed, but this isn't the case.
It's taken a while to get this far but I've made a couple of discoveries.
The reason I've picked up on this is during testing. My aim was to catch any errors connecting to an API we use which we connect to using a NuSoap client.
When I changed the username/password to make them deliberately incorrect, I found that PHP notices were being outputted from the NuSoap class - however my error reporting level is set to 0.
The error is a PHP Notice (Undefined index)
I have a library which included the main NuSoap class:
<?php
if(!defined('BASEPATH')) {
exit('No direct script access allowed');
}
class NuSoap {
var $nusoap_client;
public function __construct() {
/* Load the NuSoap class */
require_once('../httpdocs/application/libraries/nusoap/nusoap.php');
/* Initialise the NuSoap client */
$this->nusoap_client = new nusoap_client(NUSOAP_WSDL_FILE, 'wsdl', '', '', '', '', 120, 120);
/* Set the credentials */
$this->nusoap_client->set_credentials(USERNAME, PASSWORD);
$this->nusoap_client = $this->nusoap_client->getProxy();
}
}
?>
And the error is coming from the included file /application/libraries/nusoap/nusoap.php
In a seperate controller, which doesn't use the NuSoap library, I placed the following code in the index function:
$arr = array(); $arr['exists'] = true;
echo 'deliberate error - ' . $arr['not_exists'];
die(phpinfo());
Now going on the fact that the NuSoap class is outputting a notice for an undefined error, I would also expect the above to, but it doesn't.
Also - in the PHP Info output the following doesn't make sense to me:
Directive Local Value Master Value
display_errors On On
If display_errors is on - why are they not being outputted here?
To suppress the errors being generated in nusoap.php, I've found that putting error_reporting(0) at the top of the file will do this. What I can't understand is why the error reporting configuration in CodeIgniter isn't affecting this file even though it is loaded in by a CodeIgniter library?
It seems that it was only happening in a library when another library was loaded before the library in question.
The library causing the issue was PHPGrid, which was setting display_errors to 1.
In my project to catch all the PHP errors I have set up my error handling mechanism as follows:
I have set error_reporting() in index.php file which overrides
anything in the php.ini file
An error handler is set in system/codeigniter/CodeIgniter.php using
set_error_handler - this error handler, _exception_handler, is
found in system/codeigniter/Common.php
The _exception_handler function ignores E_STRICT errors, calls the
show_php_error function From the Exceptions system library if the
severity is that specified by your error_reporting() function in
index.php and logs the error according to whatever you have set up in your config.php file
The handler returns FALSE so after this PHP goes on to handle the
error however it normally would according your error_reporting level
and display_errors setting.
The thing that is puzzling me is that E_ERROR errors i.e. fatal errors don’t seem to be being caught by _exception_handler at all. It’s not just that show_php_error isn’t being called, it looks like the function just isn’t being called for them. This is obviously a problem as it means that they aren’t get handled by show_php_error or logged. For example if I deliberately mistype $this->load->views('foo'); in a controller, the handler doesn’t get called.
Any suggestion about error handling would be much appreciated, thanks!
Now this is a rather big debate:
Whether you should catch the fatal errors or not.
Some say that they are FATAL so you dont know in which condition is the system but I will go with the "try to do the cleanup if the error occured".
In order to catch ALL fatal errors you will need to setup a pre_system hook.
go to application/config/hooks.php and enter
$hook['pre_system'][] = array(
'class' => 'PHPFatalError',
'function' => 'setHandler',
'filename' => 'PHPFatalError.php',
'filepath' => 'hooks'
);
after that go to hooks directory and add your handling of the error:
<?php
class PHPFatalError {
public function setHandler() {
register_shutdown_function('handleShutdown');
}
}
function handleShutdown() {
if (($error = error_get_last())) {
ob_start();
echo "<pre>";
var_dump($error);
echo "</pre>";
$message = ob_get_clean();
sendEmail($message);
ob_start();
echo '{"status":"error","message":"Internal application error!"}';
ob_flush();
exit();
}
}
as you can see we are using the register_shutdown_function to run a function that checks if an error had occured and if it had send it via email to the developer.
This setup is working flawlessly for over 2 years in several CI projects that I have been working with.
I've found this answer under an other question (https://stackoverflow.com/a/3675357), and i think it is also useful for anyone reading this question.
"For codeigniter specific error handling, you can override its 'Exception' library class by creating My_Exception class in your application/libraries folder. Copy original library function signatures into it and put in your code. It will surely work."
Simply you can handle all type of error in one file which is display
your client because of php error or any other error is not good to
display client.
Simply place file Common_Exceptions.php in core folder . Common is my because in config file I have declare $config['subclass_prefix'] = 'Common_';
Copy system\core\Exceptions.php file and paste in core\Common_Excepions file (class Common_Exceptions extends CI_Exceptions) and do your change in this file and call view for your want and display to client when error come.
NOTE: $config['log_threshold'] = 1; enable in config file for errorlog write and after you see what error come.
One more suggestion on view file which is display when error is come there place time so when you see in log then match this time and find which error is come that time
I've been reading on in particular 'error logging' And I have come up with the function 'error_log' which seem to be a good tool to use to handle the error logging. But how is the smoothest and best way to use it?
If I have a
try {
//try a database connection...
} catch (PDOException $e) {
error_log($e->getMessage(), 3, "/var/tmp/my-errors.log");
}
This would log the error in the my-errors.log file. But what If I sometime need to change the position of where the file is, a new folder, or something. If I have tons of files I need to change them all.
Now I started of thinking to use a variable to set the path to the error log. Sure that could work, but what If I want to use the error_log in a function or class method? Then I would need to set the variable as global, but that is considered bad practise! But what If I shouldn't use the function deep in a class, wouldn't that also be considered bad practise? What is a good solution here?
<?php
function legit() {
try {
if (1 == 1) {
throw new Exception('There was an error here');
}
} catch (Exception $e) {
throw new Exception('throw the error to the try-catch outside the function...');
}
}
try {
legit();
} catch (Exception $e) {
echo 'error here' . $e->getMessage();
//log it
}
This is an example of what I was talking about above (Not having the logging deep in a class/function... Is it a good way?)
Furtheron:
I am not quite sure how I should use the Exceptions in general. Let's say I want to do a INSERT to a database with SQL inside a method, would I use a try/catch and then rethrow the exception if it fails? Is that considered good practise? Examples please.
Firstly, I'd like to commend you for looking at the standard error methods within PHP. Unfortunately error_log has some limitations as you found out.
This is a long answer, read on to find out about:
Errors
Logging the error directly vs trigger_error and set_error_handler
Where good errors go bad - Fatal Errors.
Exceptions
SPL
What to do with them?
Code
Setup
Usage
TL;DR Use trigger_error for raising errors and set_error_handler for logging them.
Errors
=========
When things don't go as expected in your program, you will often want to raise an error so that someone or something is notified. An error is for a situation where the program may continue, but something noteworthy, possibly harmful or erroneous has occurred. At this point many people want to log the error immediately with their logging package of choice. I believe this is exactly the wrong thing to do. I recommend using trigger_error to raise the error so that it can be handled with a callback set by set_error_handler. Lets compare these options:
Logging the error directly
So, you have chosen your logging package. Now you are ready to spread the calls to your logger wherever an error occurs in your code. Lets look at a single call that you might make (I'll use a similar logger to the one in Jack's answer):
Logger::getLogger('standard')->error('Ouch, this hurts');
What do you need in place to run this code?
Class: Logger
Method: getLogger
Return: Object with method 'error'
These are the dependencies that are required to use this code. Everyone who wants to re-use this code will have to provide these dependencies. This means that a standard PHP configuration will no longer be sufficient to re-use your code. With the best case, using Dependency Injection you still require a logger object to be passed into all of your code that can emit an error.
Also, in addition to whatever the code is responsible for, it also has responsibility for logging the error. This goes against the Single Responsibility Principle.
We can see that logging the error directly is bad.
trigger_error to the rescue
PHP has a function called trigger_error which can be used to raise an error just like the standard functions do. The error levels that you use with it are defined in the error level constants. As a user you must use one of the user errors: E_USER_ERROR, E_USER_WARNING or the default value E_USER_NOTICE (other error levels are reserved for the standard functions etc.). Using a standard PHP function to raise the error allows the code to be re-used with any standard PHP installation! Our code is no longer responsible for logging the error (only making sure that it is raised).
Using trigger_error we only perform half of the error logging process (raising the error) and save the responsibility of responding to the error for the error handler which will be covered next.
Error Handler
We set a custom error handler with the set_error_handler function (see the code setup). This custom error handler replaces the standard PHP error handler that normally logs messages in the web server error log depending on the PHP configuration settings. We can still use this standard error handler by returning false within our custom error handler.
The custom error handler has a single responsibility: to respond to the error (including any logging that you want to do). Within the custom error handler you have full access to the system and can run any sort of logging that you want. Virtually any logger that uses the Observer design pattern will be ok (I'm not going to go into that as I believe it is of secondary importance). This should allow you to hook in new log observers to send the output to where you need it.
You have complete control to do what you like with the errors in a single maintainable part of your code. The error logging can now be changed quickly and easily from project to project or within a single project from page to page. Interestingly even # suppressed errors make it to the custom error handler with an errno of 0 which if the error_reporting mask is respected should not be reported.
When Good Errors go Bad - Fatal Errors
It is not possible to continue from certain errors. The following error levels can not be handled from a custom error handler: E_ERROR, E_PARSE, E_CORE_ERROR, E_CORE_WARNING, E_COMPILE_ERROR, E_COMPILE_WARNING. When these sorts of errors are triggered by a standard function call the custom error handler is skipped and the system shuts down. This can be generated by:
call_this_function_that_obviously_does_not_exist_or_was_misspelt();
This is a serious mistake! It is impossible to recover from, and the system is about to shut down. Our only choice is to have a register_shutdown_function deal with the shutdown. However this function is executed whenever a script completes (successful, as well as unsuccessful). Using this and error_get_last some basic information can be logged (the system is almost shutdown at this point) when the last error was a fatal error. It can also be useful to send the correct status code and show an Internal Server Error type page of your choosing.
Exceptions
=============
Exceptions can be dealt with in a very similar way to basic errors. Instead of trigger_error an exception will be thrown by your code (manually with throw new Exception or from a standard function call). Use set_exception_handler to define the callback you want to use to handle the exception with.
SPL
The Standard PHP Library (SPL) provides exceptions. They are my preferred way of raising exceptions because like trigger_error they are a standard part of PHP which does not introduce extra dependencies to your code.
What to do with them?
When an exception is thrown there are three choices that can be made:
Catch it and fix it (the code then continues as if nothing bad happened).
Catch it, append useful information and re-throw it.
Let it bubble up to a higher level.
At each level of the stack these choices are made. Eventually once it bubbles up to the highest level the callback you set with set_exception_handler will be executed. This is where your logging code belongs (for the same reasons as the error handling) rather than spread throughout catch statements in your code.
3. Code
Setup
Error Handler
function errorHandler($errno , $errstr, $errfile, $errline, $errcontext)
{
// Perform your error handling here, respecting error_reporting() and
// $errno. This is where you can log the errors. The choice of logger
// that you use is based on your preference. So long as it implements
// the observer pattern you will be able to easily add logging for any
// type of output you desire.
}
$previousErrorHandler = set_error_handler('errorHandler');
Exception Handler
function exceptionHandler($e)
{
// Perform your exception handling here.
}
$previousExceptionHandler = set_exception_handler('exceptionHandler');
Shutdown Function
function shutdownFunction()
{
$err = error_get_last();
if (!isset($err))
{
return;
}
$handledErrorTypes = array(
E_USER_ERROR => 'USER ERROR',
E_ERROR => 'ERROR',
E_PARSE => 'PARSE',
E_CORE_ERROR => 'CORE_ERROR',
E_CORE_WARNING => 'CORE_WARNING',
E_COMPILE_ERROR => 'COMPILE_ERROR',
E_COMPILE_WARNING => 'COMPILE_WARNING');
// If our last error wasn't fatal then this must be a normal shutdown.
if (!isset($handledErrorTypes[$err['type']]))
{
return;
}
if (!headers_sent())
{
header('HTTP/1.1 500 Internal Server Error');
}
// Perform simple logging here.
}
register_shutdown_function('shutdownFunction');
Usage
Errors
// Notices.
trigger_error('Disk space is below 20%.', E_USER_NOTICE);
trigger_error('Disk space is below 20%.'); // Defaults to E_USER_NOTICE
// Warnings.
fopen('BAD_ARGS'); // E_WARNING fopen() expects at least 2 parameters, 1 given
trigger_error('Warning, this mode could be dangerous', E_USER_WARNING);
// Fatal Errors.
// This function has not been defined and so a fatal error is generated that
// does not reach the custom error handler.
this_function_has_not_been_defined();
// Execution does not reach this point.
// The following will be received by the custom error handler but is fatal.
trigger_error('Error in the code, cannot continue.', E_USER_ERROR);
// Execution does not reach this point.
Exceptions
Each of the three choices from before are listed here in a generic way, fix it, append to it and let it bubble up.
1 Loggable. Let it bubble up:
// Don't catch it.
// Either it will be caught by error handler
// Or PHP will log it as a fatal error
2 Fixable:
try
{
$value = code_that_can_generate_exception();
}
catch (Exception $e)
{
// We decide to emit a notice here (a warning could also be used).
trigger_error('We had to use the default value instead of ' .
'code_that_can_generate_exception\'s', E_USER_NOTICE);
// Fix the exception.
$value = DEFAULT_VALUE;
}
// Code continues executing happily here.
3 Append:
Observe below how the code_that_can_generate_exception() does not know about $context. The catch block at this level has more information which it can append to the exception if it is useful by rethrowing it.
try
{
$context = 'foo';
$value = code_that_can_generate_exception();
}
catch (Exception $e)
{
// Raise another exception, with extra information and the existing
// exception set as the previous exception.
throw new Exception('Context: ' . $context, 0, $e);
}
It has been requested to make this answer more applicable to a larger audience, so here goes.
Preamble
Error handling is usually not the first thing you will want to think about when writing an application; as an indirect result it gets bolted on as the need arises. However, it doesn't have to cost much to leverage existing mechanisms in PHP either.
It's a fairly lengthy article, so I've broken it down into logical sets of text.
Triggering errors
Within PHP there are two distinct ways for errors to get triggered:
Errors from PHP itself (e.g. using undefined variables) or internal functions (e.g. imagecreatefromjpeg could not open a file),
Errors triggered by user code using trigger_error,
These are usually printed on your page (unless display_errors is switched off or error_reporting is zero), which should be standard for production machines unless you write perfect code like me ... moving on); those errors can also be captured, giving you a glimpse into any hitch in the code, by using set_error_handler explained later.
Throwing exceptions
Exceptions are different from errors in three main ways:
The code that handles them may be far removed from the place where they are thrown from. The variable state at the origin must be explicitly passed to the Exception constructor, otherwise you only have the stack trace.
The code between the exception and the catch is skipped entirely, whereas after an error occurs (and it was not fatal) the code still continues.
They can be extended from the main Exception class; this allows you to catch and handle specific exceptions but let others bubble down the stack until they're caught by other code. See also: http://www.php.net/manual/en/language.exceptions.php
An example of throwing exceptions is given later on.
Handling errors
Capturing and handling errors is pretty straightforward by registering an error handler, e.g.:
function my_error_handler($errno, $errstr, $errfile = 'unknown', $errline = 0, array $errcontext = array())
{
// $errcontext is very powerful, it gives you the variable state at the point of error; this can be a pretty big variable in certain cases, but it may be extremely valuable for debugging
// if error_reporting() returns 0, it means the error control operator was used (#)
printf("%s [%d] occurred in %s:%d\n%s\n", $errstr, $errno, $errfile, $errline, print_r($errcontext, true));
// if necessary, you can retrieve the stack trace that led up to the error by calling debug_backtrace()
// if you return false here, the standard PHP error reporting is performed
}
set_error_handler('my_error_handler');
For kicks, you can turn all the errors into an ErrorException as well by registering the following error handler (PHP >= 5.1):
function exception_error_handler($errno, $errstr, $errfile, $errline)
{
throw new ErrorException($errstr, $errno, 0, $errfile, $errline);
}
set_error_handler("exception_error_handler");
Handling exceptions
In most cases you handle exceptions as close as possible to the code that caused it to allow for backup plans. For instance, you attempt to insert a database record and a primary key constraint exception is thrown; you can recover by updating the record instead (contrived as most databases can handle this by themselves). Some exceptions just can't be handled locally, so you want those to cascade down. Example:
function insertRecord($user, $name)
{
try {
if (true) {
throw new Exception('This exception should not be handled here');
}
// this code is not executed
$this->db->insert('users', array('uid' => $user, 'name' => $name));
} catch (PDOException $e) {
// attempt to fix; an exception thrown here will cascade down
throw $e; // rethrow exception
// since PHP 5.3.0 you can also nest exceptions
throw new Exception("Could not insert '$name'", -1, $e);
} catch (WhatEverException $e) {
// guess what, we can handle whatever too
}
}
The slippery exception
So what happens when you don't catch an exception anywhere? You can catch that too by using set_exception_handler.
function my_exception_handler(Exception $exception)
{
// do your stuff here, just don't throw another exception here
}
set_exception_handler('my_exception_handler');
This is not encouraged unless you have no meaningful way to handle the exception anywhere in your code.
Logging the error / exception
Now that you're handling the error you have to log it somewhere. For my example, I use a project that Apache ported from Java to PHP, called LOG4PHP. There are others, but it illustrates the importance of a flexible logging facility.
It uses the following concepts:
Loggers - named entities that perform logging upon your behalf; they can be specific to a class in your project or shared as a common logger,
Appenders - each log request can be sent to one or more destinations (email, database, text file) based on predefined conditions (such as log level),
Levels - logs are classified from debug messages to fatal errors.
Basic usage to illustrate different message levels:
Logger::getLogger('main')->info('We have lift off');
Logger::getLogger('main')->warn('Rocket is a bit hot');
Logger::getLogger('main')->error('Houston, we have a problem');
Using these concepts you can model a pretty powerful logging facility; for example, without changing above code, you can implement the following setup:
Collect all debug messages in a database for developers to look at; you might disable this on the production server,
Collect warnings into a daily file that you might email at the end of the day,
Have immediate emails sent on fatal errors.
Define it, then use it :)
define('ERRORLOG_PATH', '/var/tmp/my-errors.log');
error_log($e->getMessage(), 3, ERRORLOG_PATH);
Alternatively just make the third parameter of error_log optional, defaulting it to the path you want.
As an addition, for error logging (and in fact all logging) I would use event dispatcher, in a way that symfony framework does.
Take a look at this sf component (its very lightweight dependency, entire framework is not required, there are maybe 3 relevant php classes and 2 interfaces)
https://github.com/symfony/EventDispatcher
this way you can create dispatcher somewhere in your application bootstrap:
use Symfony\Component\EventDispatcher\EventDispatcher;
use Symfony\Component\EventDispatcher\Event;
$dispatcher = new EventDispatcher();
//register listeners
$dispatcher->addListener('application.log', function (Event $event) {
//do anything you want
});
Then you can raise an event in any place of your code by something like
$dispatcher->dispatch(new GenericEvent('application.log', array('message' => 'some log', 'priority' => 'high'));
Of course you can subclass event class with your own events:
class LogEvent extends GenericEvent {
public function __construct($message, $priority = 'INFO') {
parent::__construct('application.log', array('message'=>$message,'priority'=>$priority));
}
public function getMessage() { return $this->getArgument('message'); }
public function getPriority() { return $this->getArgument('priority'); }
}
// now raising LogEvent is much cleaner:
$dispatcher->dispatch(new LogEvent('some log'));
This will also allow you to create more customized events like ExceptionEvent
class ExceptionEvent extends GenericEvent {
public function __construct(Exception $cause) {
parent::__construct('exception.event', array('cause' => $cause));
}
}
And handle them accordingly.
Advantages
you separate logging logic from your application
you can easily add and remove loggers in runtime
you can easily register as many loggers you want (i.e. DebugLogger which logs everything into text file, ErrorLogger which logs only errors to error_log, CriticalLogger which logs only critical errors on production environment and sends them by email to administrator, etc.)
you can use event dispatcher for more things than just logging (in fact for every job for which observer pattern is appropriate)
actual logger becomes nothing more than 'implementation detail' - it's so easy to replace that it doesn't matter where your logs go - you will be able to replace log destination at any time without having to refactor names of your methods, or changing anything in code.
it will be easy to implement complex log routing logic or globally change log format (by configuring loggers)
everything becomes even more flexible if you use dependency injection for both listeners (loggers) and dispatcher (into classes that notifies log event)
Actual Logging
As someone already stated, I would advice to go with out-of-the-box library, like mentioned Monolog, Zend_Log or log4php, there is probably no reason to code these things by hand (and the last thing you want is broken error logger!)
PS: Treat code snippets as pseudo-code, I didn't test them. Details can be found in docs of mentioned libraries.
If you still need a custom way of handling logs (i.e. you don't want to use standard trigger_error()), I'd recommend looking at Zend_Log (http://framework.zend.com/manual/en/zend.log.overview.html) for these reasons:
this can be used as a standalone component, ZF is not a full-stack framework. You may copy only Zend_Loader and Zend_Log namespaces , instantiate Zend_Loader and use it. See below:
require_once('Zend/Loader/Autoloader.php');
$loader = Zend_Loader_Autoloader::getInstance();
$logger = new Zend_Log();
$writer = new Zend_Log_Writer_Stream('php://output');
$logger->addWriter($writer);
$logger->log('Informational message', Zend_Log::INFO);
You were offered many logging libraries, but I believe that Zend team (founders of PHP lang) know what they do
You may use any writers (database, STDOUT - see above, file, whatever, you may customize it to write your own to post log messages to a web service even)
log levels
may change log format (but the one that is out-of-box is great to my mind). The above example with standard formatter will produce something like this:
2012-05-07T23:57:23+03:00 INFO (6): Informational message
just read the reference, it may be configured to catch php errors
If the PHP way of handling errors is not flexible enough for you (e.g. sometimes you want to log to database, sometimes to file, sometimes whatever else), you need to use / create a custom PHP logging framework.
You can browse through the discussion in https://stackoverflow.com/questions/341154/php-logging-framework or just go and give the top choice, KLogger, a try. I am not sure, though, if it supports custom destinations for logging. But at the very least, it's a small and easy-to-read class and you should be able to extend it further for your own needs.
I'd go with Tom vand der Woerdt's logging solution, simplest and most effective for your requirements.
As for the other question:
You do not need to catch / rethrow the exception inside the function unless there is a specific kind of exception you have a solution for.
Somewhat simplistic example:
define('ERRORLOG_PATH', '/var/tmp/my-errors.log');
function do_something($in)
{
if (is_good($in))
{
try {
return get_data($in);
} catch (NoDataException $e) {
// Since it's not too big a deal that nothing
// was found, we just return false.
return false;
}
} else {
throw new InvalidArguementException('$in is not good');
}
}
function get_data($data)
{
if (!is_int($data))
{
InvalidArguementException('No');
}
$get = //do some getting.
if (!$get)
{
throw new NoDataException('No data was found.');
} else {
return $get;
}
}
try {
do_something('value');
} catch (Exception $e) {
error_log($e->getMessage(), 3, ERRORLOG_PATH);
die ('Something went wrong :(');
}
Here you'd only catch the NoDataException because you have some other logic to sort that out, all other errors fall though to the first catch and are handled by the top catch because all thrown exceptions must at some point in their hierarchy inherit from Exception.
Obviously if you throw an Exception again (outside the initial try {} or in the top catch {}) your script will exit with an Uncaught Exception error and error logging is lost.
If you wanted to go all the way, you could also implement a custom error handling function using set_error_handler() and put your logging in there too.
There are two challenges to meet. The first is to be flexible in logging to different channels. In this case you should take a look at for example Monolog.
The second challenge is to weave in that logging into your application. Imho the best case is no to use logging explicitly. Here for example aspect orientation comes in handy. A good sample is flow3.
But this is more a bird's eye view on the problem...
I use my own function which allows me to write multiple types of log files by setting or changing the second parameter.
I get past the conceptual questions you are asking about "what is the right way" to do it, by including the log function in a library of functions that I consider "native" to my development projects.
That way I can consider those functions to be just part of "MY" php core, like date() or time()
In this basic version of dlog, I also handle arrays. while I originally used this to log errors, I ended up using it for other 'quick and dirty' short term tracking such as logging the times that the code entered a certain section, and user logins, etc.
function dlog($message,$type="php-dlog")
{
if(!is_array($message) )
$message=trim($message);
error_log(date("m/d/Y h:i:s").":".print_r($message,true)."\n",3, "/data/web/logs/$_SERVER[HTTP_HOST]-$type.log");
}
Most error loggers and exception loggers are useless to most people because they haven't got access to the log files.
I prefer to use a custom error handler and a custom exception handler and have those, during production, log errors directly to the database if the system is running on a database.
During development, when display_errors are set, they log nothing as all errors gets raised in the browser.
And as a side note to that: Don't make your custom error handler throw exceptions! It's a really bad idea. It can cause bugs in the buffer handler and in some of the extensions. Also some core PHP functions like fopen() causes a warning or notice on failure, these should be dealt with accordingly and should not halt the application has an exception would do.
The mention of having the error handler throwing exceptions in the PHP documentation is a note bug.
As KNL states, which is quite right, but unfortunately as of yet undocumented, having errors throwing exceptions is not something recommended by the PHP developers and someone made a mistake in the documentation. It can indeed cause bugs with many extensions so don't do it.
This has already been debated on #PHP on irc.
The "However, errors can be simply translated to exceptions with ErrorException." on http://php.net/manual/en/language.exceptions.php is going to be removed.
I used a class that converts errors to exceptions in PHP 5 and it logs the errors to a file and/or emails them to a specified account. Is there a better way to do this? There is something about this I know can be better. I am using set_error_handler.
set_error_handler("exception_error_handler");
My code does what it should in that it logs and emails errors but am I doing the process the best way. Would it be better to log it to a Database - assuming a data connection would be present in an error. What is the industry standard for web sites?
Your code for dealing with errors must be absolutely bulletproof.
Sometimes it will kick in because of a really obscure reason that you forgot to test for, but you still want it to run when when its struggling through the code version of the apocalypse.
Writing its output to a database creates a huge dependency for you code - and the absence of the database is most likely to be a major cause of problems which would be reported.
Relying on mail is still a dependency, however the most immediate objective in the event of an outage should be to get the system working again - so sending an email is a very effective way of alerting you that you need to fix something.
PHP's file handling facilities do not lend themselves to concurrent access - so although I'd recommend logging any events locally, do not write the files from your code - use the syslog interface. By all means send an email with the relevant details after you've sent it to the syslog.
HTH
C.
I wouldn't dump that logic into the error handler.
Take a look at this method from Kohana.
/**
* PHP error handler, converts all errors into ErrorExceptions. This handler
* respects error_reporting settings.
*
* #throws ErrorException
* #return TRUE
*/
public static function error_handler($code, $error, $file = NULL, $line = NULL)
{
if (error_reporting() & $code)
{
// This error is not suppressed by current error reporting settings
// Convert the error into an ErrorException
throw new ErrorException($error, $code, 0, $file, $line);
}
// Do not execute the PHP error handler
return TRUE;
}
Clean and does what the method describes. You can now move your handling into an exception handler or inside a catch block.