When catching an exception inside a namespace it is important that you escape to the global space:
<?php
namespace SomeNamespace;
class SomeClass {
function SomeFunction() {
try {
throw new Exception('Some Error Message');
} catch (\Exception $e) {
var_dump($e->getMessage());
}
}
}
?>
Excepciones
Tabla de contenidos
PHP 5 tiene un modelo de excepciones similar al de otros lenguajes de programación.
Una excepción puede ser lanzada ("thrown"), y atrapada ("catched") dentro de
PHP. El código puede estar dentro de un bloque try para facilitar la captura
de excepciones potenciales. Cada bloque try debe tener al menos un
bloque catch o finally correspondiente.
El objeto lanzado debe ser una instancia de la clase Exception o una subclase de Exception. Intentar lanzar un objeto que no lo sea resultará en un Error Fatal de PHP.
catch
Se pueden usar múltiples bloques catch para atrapar diferentes clases de
excepciones. La ejecución normal (cuando no es lanzada ninguna excepción dentro del bloque
try) continuará después del último bloque catch definido en la sencuencia.
Las excepciones pueden ser lanzadas ("thrown") (o relanzadas) dentro de un bloque catch.
Cuando una excepción es lanzada, el código siguiente a la declaración no será
ejecutado, y PHP intentará encontrar el primer bloque catch coincidente.
Si una excepción no es capturada, se emitirá un Error Fatal de PHP con un
mensaje "Uncaught Exception ..." ("Excepción No Capturada"), a menos que se haya
definido un manejador con set_exception_handler().
finally
En PHP 5.5 y posterior, se puede utilizar un bloque finally después o
en lugar de los bloques catch. El código de dentro del bloque finally siempre se
ejecutará después de los bloques try y catch, independientemente de que se haya
lanzado una excepción o no, y antes de que la ejecución normal continúe.
Notas
Nota:
Las funciones internas de PHP utilizan principalmente la Información de Errores, sólo las extensiones Orientadas a objetos modernas utilizan excepciones. Sin embargo, los errores se pueden traducir a excepciones simplemente con ErrorException.
Sugerencia
La Biblioteca Estádar de PHP (SPL) proporciona un buen número de excepciones internas.
Ejemplos
Ejemplo #3 Lanzar una Excepción
<?php
function inverso($x) {
if (!$x) {
throw new Exception('División por cero.');
}
return 1/$x;
}
try {
echo inverso(5) . "\n";
echo inverso(0) . "\n";
} catch (Exception $e) {
echo 'Excepción capturada: ', $e->getMessage(), "\n";
}
// Continuar la ejecución
echo 'Hola Mundo\n';
?>
El resultado del ejemplo sería:
0.2 Excepción capturada: División por cero. Hola Mundo
Ejemplo #4 Manejo de excepciones con un bloque finally
<?php
function inverse($x) {
if (!$x) {
throw new Exception('División por cero.');
}
return 1/$x;
}
try {
echo inverse(5) . "\n";
} catch (Exception $e) {
echo 'Excepción capturada: ', $e->getMessage(), "\n";
} finally {
echo "Primer finally.\n";
}
try {
echo inverse(0) . "\n";
} catch (Exception $e) {
echo 'Excepción capturada: ', $e->getMessage(), "\n";
} finally {
echo "Segundo finally.\n";
}
// Continuar ejecución
echo 'Hola Mundo\n';
?>
El resultado del ejemplo sería:
0.2 Primer finally. Excepción capturada: División por cero. Segundo finally. Hola Mundo
Ejemplo #5 Excepciones anidadas
<?php
class MiExcepción extends Exception { }
class Prueba {
public function probar() {
try {
try {
throw new MiExcepción('foo!');
} catch (MiExcepción $e) {
// relanzarla
throw $e;
}
} catch (Exception $e) {
var_dump($e->getMessage());
}
}
}
$foo = new Prueba;
$foo->probar();
?>
El resultado del ejemplo sería:
string(4) "foo!"
add a note
User Contributed Notes 32 notes
zmunoz at gmail dot com ¶
13 years ago
ohcc at 163 dot com ¶
7 years ago
If a TRY has a FINALLY, a RETURN either in the TRY or a CATCH won't terminate the script. Code in the same block after the RETURN will not be executed, and the RETURN itself will be "copied" to the bottom of the FINALLY block to be executed.
a RETURN in the FINALLY block will override value(s) returned from the TRY or a CATCH block.
An EXIT or a DIE always terminate the script after themselves.
code 1
<?php
function foo(){
$bar = 1;
try{
throw new Exception('I am Wu Xiancheng.');
}catch(Exception $e){
return $bar;
$bar--; // this line will be ignored
}finally{
$bar++;
}
}
echo foo(); // 2
?>
code 2
<?php
function foo(){
$bar = 1;
try{
throw new Exception('I am Wu Xiancheng.');
}catch(Exception $e){
return $bar;
$bar--; // this line will be ignored
}finally{
$bar++;
return $bar;
}
}
echo foo(); //2
?>
code 3
<?php
function foo(){
$bar = 1;
try{
throw new Exception('I am Wu Xiancheng.');
}catch(Exception $e){
return $bar;
$bar--; // this line will be ignored
}finally{
return 100;
}
}
echo foo(); //100
?>
shaman_master at list dot ru ¶
4 years ago
Example for PHP 7.0 or latest:
<?php
namespace SomeNamespace;
use Throwable, Exception, Error;
class SomeClass
{
public function someMethod()
{
try {
if (rand(0, 1)) {
throw new Exception('Some message');
} else {
throw new Error('Some message');
}
} catch (Throwable $e) {
\var_dump($e->getMessage());
}
}
public function __toString()
{
try {
return (string) $this->someMethod();
} finally {
return '';
}
}
}
?>
ask at nilpo dot com ¶
14 years ago
If you intend on creating a lot of custom exceptions, you may find this code useful. I've created an interface and an abstract exception class that ensures that all parts of the built-in Exception class are preserved in child classes. It also properly pushes all information back to the parent constructor ensuring that nothing is lost. This allows you to quickly create new exceptions on the fly. It also overrides the default __toString method with a more thorough one.
<?php
interface IException
{
/* Protected methods inherited from Exception class */
public function getMessage(); // Exception message
public function getCode(); // User-defined Exception code
public function getFile(); // Source filename
public function getLine(); // Source line
public function getTrace(); // An array of the backtrace()
public function getTraceAsString(); // Formated string of trace
/* Overrideable methods inherited from Exception class */
public function __toString(); // formated string for display
public function __construct($message = null, $code = 0);
}
abstract class CustomException extends Exception implements IException
{
protected $message = 'Unknown exception'; // Exception message
private $string; // Unknown
protected $code = 0; // User-defined exception code
protected $file; // Source filename of exception
protected $line; // Source line of exception
private $trace; // Unknown
public function __construct($message = null, $code = 0)
{
if (!$message) {
throw new $this('Unknown '. get_class($this));
}
parent::__construct($message, $code);
}
public function __toString()
{
return get_class($this) . " '{$this->message}' in {$this->file}({$this->line})\n"
. "{$this->getTraceAsString()}";
}
}
?>
Now you can create new exceptions in one line:
<?php
class TestException extends CustomException {}
?>
Here's a test that shows that all information is properly preserved throughout the backtrace.
<?php
function exceptionTest()
{
try {
throw new TestException();
}
catch (TestException $e) {
echo "Caught TestException ('{$e->getMessage()}')\n{$e}\n";
}
catch (Exception $e) {
echo "Caught Exception ('{$e->getMessage()}')\n{$e}\n";
}
}
echo '<pre>' . exceptionTest() . '</pre>';
?>
Here's a sample output:
Caught TestException ('Unknown TestException')
TestException 'Unknown TestException' in C:\xampp\htdocs\CustomException\CustomException.php(31)
#0 C:\xampp\htdocs\CustomException\ExceptionTest.php(19): CustomException->__construct()
#1 C:\xampp\htdocs\CustomException\ExceptionTest.php(43): exceptionTest()
#2 {main}
David Spector ¶
4 years ago
This page states, "Code may be surrounded in a try block, to facilitate the catching of potential exceptions." There are two ways in which code may be "surrounded". The obvious (intuitive) way is lexical enclosure: all the code to be protected by the try block is surrounded like this:
try
{
A();
function A()
{
throw new Exception('error');
echo "A()";
} // A
} // try
catch...
The other way to enclose is by execution (dynamic enclosure), like this:
try
{
A();
} // try
catch...
function A()
{
throw new Exception('error');
echo "A()";
} // A
The sense in which code is "surrounded" for exception handling is dynamic (the second example above). This is because exception handling is dynamic and works by "unwinding" the execution stack.
christof+php[AT]insypro.com ¶
6 years ago
In case your E_WARNING type of errors aren't catchable with try/catch you can change them to another type of error like this:
<?php
set_error_handler(function($errno, $errstr, $errfile, $errline){
if($errno === E_WARNING){
// make it more serious than a warning so it can be caught
trigger_error($errstr, E_ERROR);
return true;
} else {
// fallback to default php error handler
return false;
}
});
try {
// code that might result in a E_WARNING
} catch(Exception $e){
// code to handle the E_WARNING (it's actually changed to E_ERROR at this point)
} finally {
restore_error_handler();
}
?>
hweidmann at online dot de ¶
8 years ago
catch doesn't check for the existence of the Exception class, so avoid typo.
<?php
class MyException extends Exception
{
...
}
try
{
throw new MyException(...);
}
catch (MuException $e) // <--- typo
{
...
}
?>
You WON'T get
Fatal error: Class MuException could not be loaded ...
You WILL get
Fatal error: Uncaught exception 'MyException' ...
php at marcuspope dot com ¶
10 years ago
Using a return statement inside a finally block will override any other return statement or thrown exception from the try block and all defined catch blocks. Code execution in the parent stack will continue as if the exception was never thrown.
Frankly this is a good design decision because it means I can optionally dismiss all thrown exceptions from 1 or more catch blocks in one place, without having to nest my whole try block inside an additional (and otherwise needless) try/catch block.
This is the same behavior as Java, whereas C# throws a compile time error when a return statement exists inside a finally block. So I figured it was worth pointing out to PHP devs who may not have any exposure to finally blocks or how other languages do it.
<?php
function asdf()
{
try {
throw new Exception('error');
}
catch(Exception $e) {
echo "An error occurred";
throw $e;
}
finally {
//This overrides the exception as if it were never thrown
return "\nException erased";
}
}
try {
echo asdf();
}
catch(Exception $e) {
echo "\nResult: " . $e->getMessage();
}
?>
The output from above will look like this:
An error occurred
Exception erased
Without the return statement in the finally block it would look like this:
An error occurred
Result: error
Johan ¶
12 years ago
Custom error handling on entire pages can avoid half rendered pages for the users:
<?php
ob_start();
try {
/*contains all page logic
and throws error if needed*/
...
} catch (Exception $e) {
ob_end_clean();
displayErrorPage($e->getMessage());
}
?>
ohcc at 163 dot com ¶
8 years ago
Type declarations will trigger Uncaught TypeError when a different type is passed. And it cannot be caught with the Exception class.
<?php
function xc(array $a){
}
try{
xc(4);
}catch (Exception $e){ // failed to catch it
echo $e->getMessage();
}
?>
You should use TypeError instead for PHP 7+,
<?php
function xc(array $a){
}
try{
xc(4);
}catch (TypeError $e){
echo $e->getMessage();
}
?>
In php version prior to 7.0, you should translate Catchable fatal errors to an exception and then catch it.
<?php
function exceptionErrorHandler($errNumber, $errStr, $errFile, $errLine ) {
throw new ErrorException($errStr, 0, $errNumber, $errFile, $errLine);
}
set_error_handler('exceptionErrorHandler');
function s(array $a){
}
try{
s(4);
}catch (Exception $e){
echo $e->getMessage();
}
?>
mlaopane at gmail dot com ¶
6 years ago
<?php
/**
* You can catch exceptions thrown in a deep level function
*/
function employee()
{
throw new \Exception("I am just an employee !");
}
function manager()
{
employee();
}
function boss()
{
try {
manager();
} catch (\Exception $e) {
echo $e->getMessage();
}
}
boss(); // output: "I am just an employee !"
jazfresh at hotmail.com ¶
17 years ago
Sometimes you want a single catch() to catch multiple types of Exception. In a language like Python, you can specify multiple types in a catch(), but in PHP you can only specify one. This can be annoying when you want handle many different Exceptions with the same catch() block.
However, you can replicate the functionality somewhat, because catch(<classname> $var) will match the given <classname> *or any of it's sub-classes*.
For example:
<?php
class DisplayException extends Exception {};
class FileException extends Exception {};
class AccessControl extends FileException {}; // Sub-class of FileException
class IOError extends FileException {}; // Sub-class of FileException
try {
if(!is_readable($somefile))
throw new IOError("File is not readable!");
if(!user_has_access_to_file($someuser, $somefile))
throw new AccessControl("Permission denied!");
if(!display_file($somefile))
throw new DisplayException("Couldn't display file!");
} catch (FileException $e) {
// This block will catch FileException, AccessControl or IOError exceptions, but not Exceptions or DisplayExceptions.
echo "File error: ".$e->getMessage();
exit(1);
}
?>
Corollary: If you want to catch *any* exception, no matter what the type, just use "catch(Exception $var)", because all exceptions are sub-classes of the built-in Exception.
jake at NOSPAM dot qzdesign dot co dot uk ¶
6 years ago
Don't forget if your source file is in a namespace you will need to
<?php
use Throwable; // PHP 7
use Exception;
?>
or type the fully qualified class name (prefixed with `\`) as in
<?php
try {
// ...
} catch(\Throwable $e) {
// PHP 7
} catch(\Exception $e) {
// PHP 5
}
?>
otherwise you will only ever catch exceptions of the possibly non-existent classes `\YourNamespace\Throwable` and `\YourNamespace\Exception`!
jim at anderos dot com ¶
10 years ago
If you are using a namespace, you must indicate the global namespace when using Exceptions.
<?php
namespace alpha;
function foo(){
throw new \Exception("Something is wrong!");
// throw new Exception(""); will fail
}
try {
foo();
} catch( \Exception $e ) {
// catch( Exception $e ) will give no warning, but will not catch Exception
echo "ERROR: $e";
}
?>
Shot (Piotr Szotkowski) ¶
15 years ago
‘Normal execution (when no exception is thrown within the try block, *or when a catch matching the thrown exception’s class is not present*) will continue after that last catch block defined in sequence.’
‘If an exception is not caught, a PHP Fatal Error will be issued with an “Uncaught Exception …” message, unless a handler has been defined with set_exception_handler().’
These two sentences seem a bit contradicting about what happens ‘when a catch matching the thrown exception’s class is not present’ (and the second sentence is actually correct).
sander at rotorsolutions dot nl ¶
10 years ago
Just an example why finally blocks are usefull (5.5)
<?php
//without catch
function example() {
try {
//do something that throws an exeption
}
finally {
//this code will be executed even when the exception is executed
}
}
function example2() {
try {
//open sql connection check user as example
if(condition) {
return false;
}
}
finally {
//close the sql connection, this will be executed even if the return is called.
}
}
?>
Simo ¶
9 years ago
#3 is not a good example. inverse("0a") would not be caught since (bool) "0a" returns true, yet 1/"0a" casts the string to integer zero and attempts to perform the calculation.
Edu ¶
10 years ago
The "finally" block can change the exception that has been throw by the catch block.
<?php
try{
try {
throw new \Exception("Hello");
} catch(\Exception $e) {
echo $e->getMessage()." catch in\n";
throw $e;
} finally {
echo $e->getMessage()." finally \n";
throw new \Exception("Bye");
}
} catch (\Exception $e) {
echo $e->getMessage()." catch out\n";
}
?>
The output is:
Hello catch in
Hello finally
Bye catch out
telefoontoestel at nospam dot org ¶
9 years ago
When using finally keep in mind that when a exit/die statement is used in the catch block it will NOT go through the finally block.
<?php
try {
echo "try block<br />";
throw new Exception("test");
} catch (Exception $ex) {
echo "catch block<br />";
} finally {
echo "finally block<br />";
}
// try block
// catch block
// finally block
?>
<?php
try {
echo "try block<br />";
throw new Exception("test");
} catch (Exception $ex) {
echo "catch block<br />";
exit(1);
} finally {
echo "finally block<br />";
}
// try block
// catch block
?>
cyrus+php at boadway dot ca ¶
10 years ago
There's some inconsistent behaviour associated with PHP 5.5.3's finally and return statements. If a method returns a variable in a try block (e.g. return $foo;), and finally modifies that variable, the /modified/ value is returned. However, if the try block has a return that has to be evaluated in-line (e.g. return $foo+0;), finally's changes to $foo will /not/ affect the return value.
[code]
function returnVariable(){
$foo = 1;
try{
return $foo;
} finally {
$foo++;
}
}
function returnVariablePlusZero(){
$foo = 1;
try{
return $foo + 0;
} finally {
$foo++;
}
}
$test1 = returnVariable(); // returns 2, not the correct value of 1.
$test2 = returnVariablePlusZero(); // returns correct value of 1, but inconsistent with $test1.
[/code]
It looks like it's trying to be efficient by not allocating additional memory for the return value when it thinks it doesn't have to, but the spec is that finally is run after try is completed execution, and that includes the evaluation of the return expression.
One could argue (weakly) that the first method should be the correct result, but at least the two methods should be consistent.
Tom Polomsk ¶
9 years ago
Contrary to the documentation it is possible in PHP 5.5 and higher use only try-finally blocks without any catch block.
wisetips at gmail dot com ¶
5 years ago
You should put your whole program into a try/catch block. Doing so is considered a best practice, because it will allow the user to continue to work even when there are errors in the page!
michael dot ochs at gmx dot net ¶
16 years ago
Actually it isn't possible to do:
<?php
someFunction() OR throw new Exception();
?>
This leads to a T_THROW Syntax Error. If you want to use this kind of exceptions, you can do the following:
<?php
function throwException($message = null,$code = null) {
throw new Exception($message,$code);
}
someFunction() OR throwException();
?>
Mohammad Hossein Darvishanpour ¶
8 years ago
<?php
function Test_Extention($var1)
{
if($var1 == false)
{
throw new Exception('Invalid !');
}
}//end function
try
{
Test_Extention(false);
printf("%s","Valid");
}
catch(Exception $e)
{
printf("%s","Message : " . $e->getMessage());
}
?>
Sawsan ¶
12 years ago
the following is an example of a re-thrown exception and the using of getPrevious function:
<?php
$name = "Name";
//check if the name contains only letters, and does not contain the word name
try
{
try
{
if (preg_match('/[^a-z]/i', $name))
{
throw new Exception("$name contains character other than a-z A-Z");
}
if(strpos(strtolower($name), 'name') !== FALSE)
{
throw new Exception("$name contains the word name");
}
echo "The Name is valid";
}
catch(Exception $e)
{
throw new Exception("insert name again",0,$e);
}
}
catch (Exception $e)
{
if ($e->getPrevious())
{
echo "The Previous Exception is: ".$e->getPrevious()->getMessage()."<br/>";
}
echo "The Exception is: ".$e->getMessage()."<br/>";
}
?>
jon at hackcraft dot net ¶
17 years ago
Further to dexen at google dot me dot up with "use destructors to perform a cleanup in case of exception". The fact that PHP5 has destructors, exception handling, and predictable garbage collection (if there's a single reference in scope and the scope is left then the destructor is called immediately) allows for the use of the RAII idiom.
http://en.wikipedia.org/wiki/Resource_Acquisition_Is_Initialization and my own http://www.hackcraft.net/RAII/ describe this.
daviddlowe dot flimm at gmail dot com ¶
6 years ago
Starting in PHP 7, the classes Exception and Error both implement the Throwable interface. This means, if you want to catch both Error instances and Exception instances, you should catch Throwable objects, like this:
<?php
try {
throw new Error( "foobar" );
// or:
// throw new Exception( "foobar" );
}
catch (Throwable $e) {
var_export( $e );
}
?>
fjoggen at gmail dot com ¶
17 years ago
This code will turn php errors into exceptions:
<?php
function exceptions_error_handler($severity, $message, $filename, $lineno) {
throw new ErrorException($message, 0, $severity, $filename, $lineno);
}
set_error_handler('exceptions_error_handler');
?>
However since <?php set_error_handler()?> doesn't work with fatal errors, you will not be able to throw them as Exceptions.
sander at rotorsolutions dot nl ¶
10 years ago
Just an example why finally blocks are usefull (5.5)
<?php
//without catch
function example() {
try {
//do something that throws an exeption
}
finally {
//this code will be executed even when the exception is executed
}
}
function example2() {
try {
//open sql connection check user as example
if(condition) {
return false;
}
}
finally {
//close the sql connection, this will be executed even if the return is called.
}
}
alex dowgailenko [at] g mail . com ¶
12 years ago
If you use the set_error_handler() to throw exceptions of errors, you may encounter issues with __autoload() functionality saying that your class doesn't exist and that's it.
If you do this:
<?php
class MyException extends Exception
{
}
class Tester
{
public function foobar()
{
try
{
$this->helloWorld();
} catch (MyException $e) {
throw new Exception('Problem in foobar',0,$e);
}
}
protected function helloWorld()
{
throw new MyException('Problem in helloWorld()');
}
}
$tester = new Tester;
try
{
$tester->foobar();
} catch (Exception $e) {
echo $e->getTraceAsString();
}
?>
The trace will only show $tester->foobar() and not the call made to $tester->helloWorld().
In other words, if you pass a previous exception to a new one, the previous exception's stack trace is taken into account in the new exception.
Hayley Watson ¶
9 years ago
Remember that Exceptions are also objects and can be handled as such; they can be constructed in and returned as values from functions, passed as arguments to other functions, and examined before being thrown. You don't have to throw it as soon as you have constructed it (the stack trace will of course reflect the moment the Exception was constructed, not the moment it was thrown).
You might, for example, want to collect additional information to include in YourException but you don't want to clutter up the YourException class or the code containing the "throw" statement by collecting the information there. Or you might want to do something (such as logging) with each Exception that is thrown from a certain region (catch it, pass it to the logging function, then rethrow it).
jenshausdorf at gmail dot com ¶
6 years ago
Please don't do something like this:
<?php
try {
// experimental stuff to check whether something works
} catch(\Throwable $e) {
return false;
} finally {
return true;
}
?>
Well, it is allowed syntax, it is bad practice, because once it hits the exception block, finally won't be called(because it exits the scope). Finally was invented to prevent duplicated code after one operation, regardless whether it was successful(for example closing the connection to a server). This way, you don't have any duplicated code. So you don't need to use this structure.
