When to use ErrorException vs Exception? - php

PHP 5.1 has introduced ErrorException. The constructor of the two functions differs
public __construct ([ string $message = "" [, int $code = 0 [, Exception $previous = NULL ]]] )
public __construct ([ string $message = "" [, int $code = 0 [, int $severity = 1 [, string $filename = __FILE__ [, int $lineno = __LINE__ [, Exception $previous = NULL ]]]]]] )
Is there a difference when to use either?
I suspect that the above use case is incorrect:
<?php
class Data {
public function save () {
try {
// do something
} catch (\PDOException $e) {
if ($e->getCode() == '23000') {
throw new Data_Exception('Foo Bar', $e);
}
throw $e
}
}
}
class Data_Exception extends ErrorException /* This should not be using ErrorException */ {}
It isn't documented well, but it appears that ErrorException is designed to be used explicitly from the custom error handler as in the original example, http://php.net/manual/en/class.errorexception.php.
function exception_error_handler($errno, $errstr, $errfile, $errline ) {
throw new ErrorException($errstr, $errno, 0, $errfile, $errline);
}
set_error_handler("exception_error_handler");

ErrorException is mostly used to convert php error (raised by error_reporting) to Exception.
You should avoid using directly Exception which is too wide. Subclass it with specific Exception or use predefined SPL Exception
To follow your edit : Yes extends Exception rather than ErrorException.

Related

Why does PHPUnit "receives" an Error object instead of an Exception object

When I test a constructor that throws an exception using expectExceptionMessage('exception message') the test fails and the actual message text is prefixed with "Class 'namespace\Class_Name'".
It also states that an exception of type Error was thrown instead of type Exception as expected.
Am I throwing my exception incorrectly?
I was able to make the test pass by leaving out the expectExceptionMessage function and enclosing the code in a try catch statement.
Which doesn't make sense to me.
Using the annotations
/**
* #expectedException Exception
* #expectedExceptionMessage no_file.json not found
*/
Also didn't solve the problem.
PHPUnit test code:
public function testNonExistingFileInConstructor() {
$this->expectException( 'Exception' );
$this->expectExceptionMessage( 'no_file.json not found');
new Json_File('no_file.json');
}
Code throwing the exception:
public function __construct( $path_to_file ) {
$json_file = file_get_contents( $path_to_file );
if( false === $json_file ) {
throw new Exception( $json_file . ' not found', 500 );
}
$data = json_decode( $json_file, true );
if ( is_null( $data) ) {
throw new Exception( 'invalid json in ' . $json_file, 600 );
}
$this->data = $data;
}
Do not use annotations to expect exceptions.
Always use fully qualified class names with expectException(), for instance $this->expectException(YourNamespace\Exception::class); instead of $this->expectException('Exception');. 'Exception' is just a string that cannot be resolved to the correct, fully qualified name of the exception you're expecting.

set_error_handler, catch all function returning error

I have a custom exception class.
And I've set my error handler to call a custom catchall function, which would then throw an error.
class customError extends exception {}
function catchall($number, $message, $file, $line) {
throw new customError($number, $message, 0, $file, $line);
}
set_error_handler('catchall', -1 & ~E_NOTICE & ~E_USER_NOTICE);
I get the following error: Wrong parameters for Exception([string $exception [, long $code [, Exception $previous = NULL]]])

Why not output I hope result in PHP7 using try and catch? [duplicate]

I need to catch some warnings being thrown from some php native functions and then handle them.
Specifically:
array dns_get_record ( string $hostname [, int $type= DNS_ANY [, array &$authns [, array &$addtl ]]] )
It throws a warning when the DNS query fails.
try/catch doesn't work because a warning is not an exception.
I now have 2 options:
set_error_handler seems like overkill because I have to use it to filter every warning in the page (is this true?);
Adjust error reporting/display so these warnings don't get echoed to screen, then check the return value; if it's false, no records is found for hostname.
What's the best practice here?
Set and restore error handler
One possibility is to set your own error handler before the call and restore the previous error handler later with restore_error_handler().
set_error_handler(function() { /* ignore errors */ });
dns_get_record();
restore_error_handler();
You could build on this idea and write a re-usable error handler that logs the errors for you.
set_error_handler([$logger, 'onSilencedError']);
dns_get_record();
restore_error_handler();
Turning errors into exceptions
You can use set_error_handler() and the ErrorException class to turn all php errors into exceptions.
set_error_handler(function($errno, $errstr, $errfile, $errline) {
// error was suppressed with the #-operator
if (0 === error_reporting()) {
return false;
}
throw new ErrorException($errstr, 0, $errno, $errfile, $errline);
});
try {
dns_get_record();
} catch (ErrorException $e) {
// ...
}
The important thing to note when using your own error handler is that it will bypass the error_reporting setting and pass all errors (notices, warnings, etc.) to your error handler. You can set a second argument on set_error_handler() to define which error types you want to receive, or access the current setting using ... = error_reporting() inside the error handler.
Suppressing the warning
Another possibility is to suppress the call with the # operator and check the return value of dns_get_record() afterwards. But I'd advise against this as errors/warnings are triggered to be handled, not to be suppressed.
The solution that really works turned out to be setting simple error handler with E_WARNING parameter, like so:
set_error_handler("warning_handler", E_WARNING);
dns_get_record(...)
restore_error_handler();
function warning_handler($errno, $errstr) {
// do something
}
Be careful with the # operator - while it suppresses warnings it also suppresses fatal errors. I spent a lot of time debugging a problem in a system where someone had written #mysql_query( '...' ) and the problem was that mysql support was not loaded into PHP and it threw a silent fatal error. It will be safe for those things that are part of the PHP core but please use it with care.
bob#mypc:~$ php -a
Interactive shell
php > echo #something(); // this will just silently die...
No further output - good luck debugging this!
bob#mypc:~$ php -a
Interactive shell
php > echo something(); // lets try it again but don't suppress the error
PHP Fatal error: Call to undefined function something() in php shell code on line 1
PHP Stack trace:
PHP 1. {main}() php shell code:0
bob#mypc:~$
This time we can see why it failed.
I wanted to try/catch a warning, but at the same time keep the usual warning/error logging (e.g. in /var/log/apache2/error.log); for which the handler has to return false. However, since the "throw new..." statement basically interrupts the execution, one then has to do the "wrap in function" trick, also discussed in:
Is there a static way to throw exception in php
Or, in brief:
function throwErrorException($errstr = null,$code = null, $errno = null, $errfile = null, $errline = null) {
throw new ErrorException($errstr, 0, $errno, $errfile, $errline);
}
function warning_handler($errno, $errstr, $errfile, $errline, array $errcontext) {
return false && throwErrorException($errstr, 0, $errno, $errfile, $errline);
# error_log("AAA"); # will never run after throw
/* Do execute PHP internal error handler */
# return false; # will never run after throw
}
...
set_error_handler('warning_handler', E_WARNING);
...
try {
mkdir($path, 0777, true);
} catch (Exception $e) {
echo $e->getMessage();
// ...
}
EDIT: after closer inspection, it turns out it doesn't work: the "return false && throwErrorException ..." will, basically, not throw the exception, and just log in the error log; removing the "false &&" part, as in "return throwErrorException ...", will make the exception throwing work, but will then not log in the error_log... I'd still keep this posted, though, as I haven't seen this behavior documented elsewhere.
Combining these lines of code around a file_get_contents() call to an external url helped me handle warnings like "failed to open stream: Connection timed out" much better:
set_error_handler(function ($err_severity, $err_msg, $err_file, $err_line, array $err_context)
{
throw new ErrorException( $err_msg, 0, $err_severity, $err_file, $err_line );
}, E_WARNING);
try {
$iResult = file_get_contents($sUrl);
} catch (Exception $e) {
$this->sErrorMsg = $e->getMessage();
}
restore_error_handler();
This solution works within object context, too. You could use it in a function:
public function myContentGetter($sUrl)
{
... code above ...
return $iResult;
}
Normaly you should never use # unless this is the only solution. In that specific case the function dns_check_record should be use first to know if the record exists.
If dns_get_record() fails, it should return FALSE, so you can suppress the warning with # and then check the return value.
You should probably try to get rid of the warning completely, but if that's not possible, you can prepend the call with # (i.e. #dns_get_record(...)) and then use any information you can get to figure out if the warning happened or not.
try checking whether it returns some boolean value then you can simply put it as a condition. I encountered this with the oci_execute(...) which was returning some violation with my unique keys.
ex.
oci_parse($res, "[oracle pl/sql]");
if(oci_execute){
...do something
}
As of PHP8, you can do the following instead of setting error handlers to catch Errors and Warnings. I Believe in PHP 7.something you could catch some Errors.
try {
call_user_func('sprintf', array_merge([$string], $args));
} catch (Throwable $e) {
$logger->info('mesage...');
}
You should generally be somewhere that you can pass or access a logger if you bulkhead in this way, as it can obfuscate coder errors, such as passing incorrectly typed parameters to a method, and mask a variety of other problems.
https://php.watch/versions/8.0/internal-function-exceptions
Not sure if notices are caught (likely not), but you can likely solve around examples like this one, by thinking a little more about what you are looking to do.
Both builder pattern, and options patterns provide solutions for this where prior to the site of call, which can be a private function or just after validity checks, you can throw a real custom exception that is attributable only to your code. That will make even built-in functions very safe to use.
One other nice practice is to use either debug_backtrace, with DEBUG_BACKTRACE_IGNORE_ARGS or use the getTrace or getTraceAsString methods on the Throwable so that some of the context is preseved.
FolderStructure
index.php //Script File
logs //Folder for log Every warning and Errors
CustomException.php //Custom exception File
CustomException.php
/**
* Custom error handler
*/
function handleError($code, $description, $file = null, $line = null, $context = null) {
$displayErrors = ini_get("display_errors");;
$displayErrors = strtolower($displayErrors);
if (error_reporting() === 0 || $displayErrors === "on") {
return false;
}
list($error, $log) = mapErrorCode($code);
$data = array(
'timestamp' => date("Y-m-d H:i:s:u", time()),
'level' => $log,
'code' => $code,
'type' => $error,
'description' => $description,
'file' => $file,
'line' => $line,
'context' => $context,
'path' => $file,
'message' => $error . ' (' . $code . '): ' . $description . ' in [' . $file . ', line ' . $line . ']'
);
$data = array_map('htmlentities',$data);
return fileLog(json_encode($data));
}
/**
* This method is used to write data in file
* #param mixed $logData
* #param string $fileName
* #return boolean
*/
function fileLog($logData, $fileName = ERROR_LOG_FILE) {
$fh = fopen($fileName, 'a+');
if (is_array($logData)) {
$logData = print_r($logData, 1);
}
$status = fwrite($fh, $logData . "\n");
fclose($fh);
// $file = file_get_contents($filename);
// $content = '[' . $file .']';
// file_put_contents($content);
return ($status) ? true : false;
}
/**
* Map an error code into an Error word, and log location.
*
* #param int $code Error code to map
* #return array Array of error word, and log location.
*/
function mapErrorCode($code) {
$error = $log = null;
switch ($code) {
case E_PARSE:
case E_ERROR:
case E_CORE_ERROR:
case E_COMPILE_ERROR:
case E_USER_ERROR:
$error = 'Fatal Error';
$log = LOG_ERR;
break;
case E_WARNING:
case E_USER_WARNING:
case E_COMPILE_WARNING:
case E_RECOVERABLE_ERROR:
$error = 'Warning';
$log = LOG_WARNING;
break;
case E_NOTICE:
case E_USER_NOTICE:
$error = 'Notice';
$log = LOG_NOTICE;
break;
case E_STRICT:
$error = 'Strict';
$log = LOG_NOTICE;
break;
case E_DEPRECATED:
case E_USER_DEPRECATED:
$error = 'Deprecated';
$log = LOG_NOTICE;
break;
default :
break;
}
return array($error, $log);
}
//calling custom error handler
set_error_handler("handleError");
just include above file into your script file like this
index.php
error_reporting(E_ALL);
ini_set('display_errors', 'off');
define('ERROR_LOG_FILE', 'logs/app_errors.log');
include_once 'CustomException.php';
echo $a; // here undefined variable warning will be logged into logs/app_errors.log
Since PHP7 you can catch most errors and warnings like so:
try {
whatever();
} catch (Throwable $e) {
}
More: https://www.php.net/manual/en/language.errors.php7.php
I would only recommend using # to suppress warnings when it's a straight forward operation (e.g. $prop = #($high/($width - $depth)); to skip division by zero warnings). However in most cases it's better to handle.

custom error handler: this phpunit test fails. Why? (PHP7)

I'm studying PHP and, meanwhile, writing toy code to understand what I study.
These are my "error and exception handler" functions.
My intention is:
to convert any "old style" PHP error in an Exception
to display the Exception
to log an error message in the syslog
function display_exception($exception)
{
print_r($exception);
}
function log_error_or_exception($error_type, $error_message, $error_number = null, $file_name = null, $line_number = null)
{
$text = 'Message: ' . $error_message . ' - ErrorType: ' . $error_type;
if ($error_number) {
$text .= ' - Error#: ' . $error_number;
}
if ($file_name) {
$text .= ' -> ' . $file_name;
}
if ($line_number) {
$text .= ':' . $line_number;
}
syslog(LOG_ERR, $text);
}
/**
* This function logs any uncaught exception that has been thrown.
* If in the "dev" environment it also displays the Exception
*
* #var Exception $exception
* #return void
*/
function custom_exception_handler($exception)
{
if (ENV == 'dev') {
display_exception($exception);
}
log_error_or_exception(get_class($exception), $exception->getMessage(), $exception->getCode(), $exception->getFile(), $exception->getLine());
}
/**
* This function converts an "old style" PHP Error in an ErrorException
*
* #var int $errno
* #var string $errstr
* #var string|null $errfile
* #var int|null $errline
* #var array $errcontext
* #return false|void
*/
function custom_error_handler(int $errno, string $errstr, string $errfile = null, int $errline = null, array $errcontext = array())
{
// if error_reporting() is false it means that the error was trigger by a line having
// the error control operator "#" so the error should never be displayed.
// Sometimes thought it's convenient to log it
if (!error_reporting()) {
if (ENV == 'dev') {
log_error_or_exception('Error', $errstr, $errno, $errfile, $errline);
}
return false;
}
throw new ErrorException($errstr, $errno, 1, $errfile, $errline);
echo "this should not be displayed";
}
set_exception_handler('custom_exception_handler');
set_error_handler('custom_error_handler');
Now I have an object
<?php
require_once 'app/src/ErrorExceptionHandlers.php';
class Obj
{
public function method($value){
$result = preg_match('/#/', $value);
}
}
If I run this code everything works as expected:
define('ENV', 'dev');
$object = new Obj;
$object->method(array());
I get:
ErrorException Object
(
[message:protected] => preg_match() expects parameter 2 to be string, array given
[string:Exception:private] =>
...
)
If I try to run this phpunit test
<?php
require_once 'app/src/models/obj.php';
define('ENV', 'dev');
class ObjTest extends \PHPUnit_Framework_TestCase
{
/**
* #ExpectedException ErrorException
*/
public function test_method(){
$object = new Obj();
$object->method(array());
}
}
I get:
There was 1 error:
1) ObjTest::test_method
ErrorException: preg_match() expects parameter 2 to be string, array given
Why does the test fail?
So, the annotation names are case sensitive.#ExpectedException should be #expectedException

Can I try/catch a warning?

I need to catch some warnings being thrown from some php native functions and then handle them.
Specifically:
array dns_get_record ( string $hostname [, int $type= DNS_ANY [, array &$authns [, array &$addtl ]]] )
It throws a warning when the DNS query fails.
try/catch doesn't work because a warning is not an exception.
I now have 2 options:
set_error_handler seems like overkill because I have to use it to filter every warning in the page (is this true?);
Adjust error reporting/display so these warnings don't get echoed to screen, then check the return value; if it's false, no records is found for hostname.
What's the best practice here?
Set and restore error handler
One possibility is to set your own error handler before the call and restore the previous error handler later with restore_error_handler().
set_error_handler(function() { /* ignore errors */ });
dns_get_record();
restore_error_handler();
You could build on this idea and write a re-usable error handler that logs the errors for you.
set_error_handler([$logger, 'onSilencedError']);
dns_get_record();
restore_error_handler();
Turning errors into exceptions
You can use set_error_handler() and the ErrorException class to turn all php errors into exceptions.
set_error_handler(function($errno, $errstr, $errfile, $errline) {
// error was suppressed with the #-operator
if (0 === error_reporting()) {
return false;
}
throw new ErrorException($errstr, 0, $errno, $errfile, $errline);
});
try {
dns_get_record();
} catch (ErrorException $e) {
// ...
}
The important thing to note when using your own error handler is that it will bypass the error_reporting setting and pass all errors (notices, warnings, etc.) to your error handler. You can set a second argument on set_error_handler() to define which error types you want to receive, or access the current setting using ... = error_reporting() inside the error handler.
Suppressing the warning
Another possibility is to suppress the call with the # operator and check the return value of dns_get_record() afterwards. But I'd advise against this as errors/warnings are triggered to be handled, not to be suppressed.
The solution that really works turned out to be setting simple error handler with E_WARNING parameter, like so:
set_error_handler("warning_handler", E_WARNING);
dns_get_record(...)
restore_error_handler();
function warning_handler($errno, $errstr) {
// do something
}
Be careful with the # operator - while it suppresses warnings it also suppresses fatal errors. I spent a lot of time debugging a problem in a system where someone had written #mysql_query( '...' ) and the problem was that mysql support was not loaded into PHP and it threw a silent fatal error. It will be safe for those things that are part of the PHP core but please use it with care.
bob#mypc:~$ php -a
Interactive shell
php > echo #something(); // this will just silently die...
No further output - good luck debugging this!
bob#mypc:~$ php -a
Interactive shell
php > echo something(); // lets try it again but don't suppress the error
PHP Fatal error: Call to undefined function something() in php shell code on line 1
PHP Stack trace:
PHP 1. {main}() php shell code:0
bob#mypc:~$
This time we can see why it failed.
I wanted to try/catch a warning, but at the same time keep the usual warning/error logging (e.g. in /var/log/apache2/error.log); for which the handler has to return false. However, since the "throw new..." statement basically interrupts the execution, one then has to do the "wrap in function" trick, also discussed in:
Is there a static way to throw exception in php
Or, in brief:
function throwErrorException($errstr = null,$code = null, $errno = null, $errfile = null, $errline = null) {
throw new ErrorException($errstr, 0, $errno, $errfile, $errline);
}
function warning_handler($errno, $errstr, $errfile, $errline, array $errcontext) {
return false && throwErrorException($errstr, 0, $errno, $errfile, $errline);
# error_log("AAA"); # will never run after throw
/* Do execute PHP internal error handler */
# return false; # will never run after throw
}
...
set_error_handler('warning_handler', E_WARNING);
...
try {
mkdir($path, 0777, true);
} catch (Exception $e) {
echo $e->getMessage();
// ...
}
EDIT: after closer inspection, it turns out it doesn't work: the "return false && throwErrorException ..." will, basically, not throw the exception, and just log in the error log; removing the "false &&" part, as in "return throwErrorException ...", will make the exception throwing work, but will then not log in the error_log... I'd still keep this posted, though, as I haven't seen this behavior documented elsewhere.
Combining these lines of code around a file_get_contents() call to an external url helped me handle warnings like "failed to open stream: Connection timed out" much better:
set_error_handler(function ($err_severity, $err_msg, $err_file, $err_line, array $err_context)
{
throw new ErrorException( $err_msg, 0, $err_severity, $err_file, $err_line );
}, E_WARNING);
try {
$iResult = file_get_contents($sUrl);
} catch (Exception $e) {
$this->sErrorMsg = $e->getMessage();
}
restore_error_handler();
This solution works within object context, too. You could use it in a function:
public function myContentGetter($sUrl)
{
... code above ...
return $iResult;
}
Normaly you should never use # unless this is the only solution. In that specific case the function dns_check_record should be use first to know if the record exists.
If dns_get_record() fails, it should return FALSE, so you can suppress the warning with # and then check the return value.
You should probably try to get rid of the warning completely, but if that's not possible, you can prepend the call with # (i.e. #dns_get_record(...)) and then use any information you can get to figure out if the warning happened or not.
try checking whether it returns some boolean value then you can simply put it as a condition. I encountered this with the oci_execute(...) which was returning some violation with my unique keys.
ex.
oci_parse($res, "[oracle pl/sql]");
if(oci_execute){
...do something
}
As of PHP8, you can do the following instead of setting error handlers to catch Errors and Warnings. I Believe in PHP 7.something you could catch some Errors.
try {
call_user_func('sprintf', array_merge([$string], $args));
} catch (Throwable $e) {
$logger->info('mesage...');
}
You should generally be somewhere that you can pass or access a logger if you bulkhead in this way, as it can obfuscate coder errors, such as passing incorrectly typed parameters to a method, and mask a variety of other problems.
https://php.watch/versions/8.0/internal-function-exceptions
Not sure if notices are caught (likely not), but you can likely solve around examples like this one, by thinking a little more about what you are looking to do.
Both builder pattern, and options patterns provide solutions for this where prior to the site of call, which can be a private function or just after validity checks, you can throw a real custom exception that is attributable only to your code. That will make even built-in functions very safe to use.
One other nice practice is to use either debug_backtrace, with DEBUG_BACKTRACE_IGNORE_ARGS or use the getTrace or getTraceAsString methods on the Throwable so that some of the context is preseved.
FolderStructure
index.php //Script File
logs //Folder for log Every warning and Errors
CustomException.php //Custom exception File
CustomException.php
/**
* Custom error handler
*/
function handleError($code, $description, $file = null, $line = null, $context = null) {
$displayErrors = ini_get("display_errors");;
$displayErrors = strtolower($displayErrors);
if (error_reporting() === 0 || $displayErrors === "on") {
return false;
}
list($error, $log) = mapErrorCode($code);
$data = array(
'timestamp' => date("Y-m-d H:i:s:u", time()),
'level' => $log,
'code' => $code,
'type' => $error,
'description' => $description,
'file' => $file,
'line' => $line,
'context' => $context,
'path' => $file,
'message' => $error . ' (' . $code . '): ' . $description . ' in [' . $file . ', line ' . $line . ']'
);
$data = array_map('htmlentities',$data);
return fileLog(json_encode($data));
}
/**
* This method is used to write data in file
* #param mixed $logData
* #param string $fileName
* #return boolean
*/
function fileLog($logData, $fileName = ERROR_LOG_FILE) {
$fh = fopen($fileName, 'a+');
if (is_array($logData)) {
$logData = print_r($logData, 1);
}
$status = fwrite($fh, $logData . "\n");
fclose($fh);
// $file = file_get_contents($filename);
// $content = '[' . $file .']';
// file_put_contents($content);
return ($status) ? true : false;
}
/**
* Map an error code into an Error word, and log location.
*
* #param int $code Error code to map
* #return array Array of error word, and log location.
*/
function mapErrorCode($code) {
$error = $log = null;
switch ($code) {
case E_PARSE:
case E_ERROR:
case E_CORE_ERROR:
case E_COMPILE_ERROR:
case E_USER_ERROR:
$error = 'Fatal Error';
$log = LOG_ERR;
break;
case E_WARNING:
case E_USER_WARNING:
case E_COMPILE_WARNING:
case E_RECOVERABLE_ERROR:
$error = 'Warning';
$log = LOG_WARNING;
break;
case E_NOTICE:
case E_USER_NOTICE:
$error = 'Notice';
$log = LOG_NOTICE;
break;
case E_STRICT:
$error = 'Strict';
$log = LOG_NOTICE;
break;
case E_DEPRECATED:
case E_USER_DEPRECATED:
$error = 'Deprecated';
$log = LOG_NOTICE;
break;
default :
break;
}
return array($error, $log);
}
//calling custom error handler
set_error_handler("handleError");
just include above file into your script file like this
index.php
error_reporting(E_ALL);
ini_set('display_errors', 'off');
define('ERROR_LOG_FILE', 'logs/app_errors.log');
include_once 'CustomException.php';
echo $a; // here undefined variable warning will be logged into logs/app_errors.log
Since PHP7 you can catch most errors and warnings like so:
try {
whatever();
} catch (Throwable $e) {
}
More: https://www.php.net/manual/en/language.errors.php7.php
I would only recommend using # to suppress warnings when it's a straight forward operation (e.g. $prop = #($high/($width - $depth)); to skip division by zero warnings). However in most cases it's better to handle.

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