How do I catch this type of error?
ContextErrorException: Catchable Fatal Error: Argument 1 passed to AA\SomeBundle\Entity\SomeEntity::setCity() must be an instance of AA\SomeBundle\Entity\City, null given, called in /srv/dev/some_path/vendor/symfony/symfony/src/Symfony/Component/PropertyAccess/PropertyAccessor.php on line 360 and defined in /srv/dev/some_path/src/AA/SomeBundle/Entity/SomeEntity.php line 788
And I am trying to catch everything like that:
$form = $this->createForm(new SomeFormType(), $instanceOfSomeEntity);
try {
$form->handleRequest($request);
} catch (\Exception $e) {
$form->addError(new FormError('missing_information'));
}
The easiest way to fix this is to prefix the offending code with the # symbol, so any warnings are suppressed. Any errors should then be caught in the try...catch.
Not ideal as # has non-trivial performance implications, but otherwise, you're looking at perhaps replacing the error handling or in my case, when reading from XML, checking the existence of every tag before trying to get the value.
This is my code, fixed by adding the '#'
try {
$value = #$this->XML->StructuredXMLResume->ContactInfo->ContactMethod->PostalAddress->DeliveryAddress->AddressLine;
} catch (\Exception $e) {
$value = '';
}
As you can imagine, checking every level down to AddressLine would be ridiculous.
You have to disable the error reporting and catch the last error with error_get_last() function, here an example, from the Symfony Finder component : https://github.com/symfony/symfony/blob/master/src/Symfony/Component/Finder/SplFileInfo.php#L65
The other way is to create a custom error handler, here an example from Monolog : https://github.com/Seldaek/monolog/blob/master/src/Monolog/ErrorHandler.php
Related
I'd like to able to catch an exception and continue with the execution of other subsequent functions (and possibly log an error in the catch section). In the code sample below, there are instances where $html->find doesn't find the element and returns error exception undefined offset. In such cases, the entire script fails. I don't want to specifically test for this error but rather any error that may occur within the code block in the try section.
public function parsePage1($provider)
{
$path = $this->getFile($provider);
$link = $this->links[$provider];
if (file_exists($path)) {
$string = file_get_contents($path);
$html = \HTMLDomParser::str_get_html($string);
$wrapper = $html->find('.classToLookFor')[0];
unset($string);
}
}
try {
$this->parsePage1('nameOfProvider');
} catch(Exception $e) {
// continue...
}
try {
$this->parsePage2('nameOfProvider');
} catch(Exception $e) {
// continue...
}
No, there is no way to make the code within the try block continue past an exception. An exception terminates the function just like a return would; there is no way to restore the state of the function afterwards.
Instead, avoid triggering the error in the first place:
$wrappers = $html->find('.classToLookFor'); # <-- no [0]!
if (count($wrappers)) {
$wrapper = $wrappers[0];
...
}
Just to be clear, the 'error' in this case was a notice. If your errorlevel does not include notices, which is typically the case in production, your code will continue past that point.
With that said, Notices and warnings are intended for developers to add checks for expected input, as in duskwuff's example.
Unfortunatley, duskwuff's answer is problematic with the most recent versions of php at 7.2+. This is because count() expects either an array or an object that implements countable.
With the newest version you will get a Warning:
Warning: count(): Parameter must be an array or an object that implements Countable in
You will be back where you were before using count() only. A simple fix for that is to add a check for is_array.
$wrappers = $html->find('.classToLookFor'); # <-- no [0]!
if (is_array($wrappers) && count($wrappers)) {
$wrapper = $wrappers[0];
...
}
I also want to point out, that per my original comment, the whole purpose of exception catching is to protect against program termination errors.
This was not a good example of the types of errors where you should apply try-catch, but to be clear, your original code does continue... just not within the try section of the code, but after the catch()
This simulation of your original problem illustrates that:
<?php
function findit($foo) {
return $foo[0];
}
try {
findit('');
} catch(Exception $e) {
var_dump($e);
}
echo 'Hey look we continued';
Output will be something like:
Notice: Uninitialized string offset: 0 in ... on line 4
Hey look we continued
I feel this needs to be added as a response because people in the future are going to probably find this question, which really has nothing much to do with try-catch handling, and really has to do with code that expects to work with an array, but might not get one.
I want to know what errors can be thrown that I am not catching, for dynamic code - not static code. For example, my code may run without throwing any Exceptions for 10 years and then throw UncaughtException
I want to specifically (non-generically) catch every type of Exception that can be thrown by the methods I am using. How can I know what Exceptions MAY be thrown by these methods?
I want to non-generically catch every type of error that can possibly be thrown for a section of PHP code.
Examples of exceptions that may be thrown:
PDOException
ExpiredException
Now I have this around everything:
try{
...
}catch(Exception $e){
...
}
I'd like to replace it with something like this:
try{
...
}catch(PDOException $e){
...
}catch(ExpiredException $e){
...
}catch(Exception $e){
...
}
I'd like to be confident that I am catching all different kinds of Exception that can be thrown by the methods in the section of code
And if I catch all Exceptions individually, will it be safe to remove this part?:
catch(Exception $e){
...
}
Or are there methods which will simply throw Exception?
My solution preference list (1 is the most-preferred solution):
1: A flag I can turn on that will cause php.exe to warn me about each and every possible type of Exception that is not specifically being caught
2: A way to individually check each method and see what errors can be thrown. Is the documentation the only way to check? or is there some IDE or PHP block that will tell me which Exceptions may be thrown by individual methods?
You can set callback function by using register_shutdown_function() which will call on every end of your php code execution. In this callback function you can check whether any error occurs or not using error_get_last().
For Example:
// Register shutdown function
register_shutdown_function("shutdownTracker");
// Define all error types you want to catch and handle
define('E_FATAL', E_ERROR | E_PARSE | E_CORE_ERROR | E_COMPILE_ERROR | E_USER_ERROR | E_RECOVERABLE_ERROR);
function shutdownTracker() {
$error = error_get_last(); // This will return empty if no error occurs while executing php code.
if(!empty($error) && ($error['type'] & E_FATAL)) {
// Write your code here to handle you error
}
}
Note: You should include this code on top of your code.
Well if you are talking exceptions, you already have the answer
try{
...
}catch(PDOException $e){
...
}catch(ExpiredException $e){
...
}catch(Exception $e){
echo get_class($e); // get's the class of unrecorded exceptions.
//catches any exceptions missed by the above
}
Now if you are talking about "errors" you can do is use a custom error handler
if(!function_exists('myErrorHandler')){
function myErrorHandler($severity, $message, $file = 'UNKNOWN', $line = 'UNKNOWN')
{
throw new ErrorException(
$message,
1,
$severity,
$file,
$line
);
}
set_error_handler('myErrorHandler');
}
What it does is convert all PHP errors to exceptions or rather to ErrorExceptoins.
Now you can go a step further and use these other two functions.
register_shutdown_function
AND
set_exception_handler
I'm actually working on porting what I use to it's own stand alone github project. Right after I finish my eJinn project, which you may be interested in. eJinn is designed to build exception classes based off a config file, so you can have one error per exception file and unique error codes in a project.
You can catch all exceptions without even call try.
function hello($e)
{
if ($e instanceof PDOException){
echo "something".
}else echo $e->getMessage();
}
set_exception_handler('hello');
this should catch all exceptions.
UPDATE 2
I've edited the code so you know what exceptions will be thrown using get_class();
class mycustomException extends Exception{} // making new exception
function hello($e)
{
if ($e instanceof PDOException){ // exception already known
echo "something";
}else{
echo get_class($e); // get exception name.
}
}
set_exception_handler('hello');
throw new mycustomException(); // throw exception that we made.
I suppose that the exception system of PHP will catch all. but it doesn't.
try{
$obj = new Asdfasdfasdf()
} catch(Exception $e){
trace(...something...)
}
But it doesn't catch this kind of error, and I have searched php document, which didn't say which kind of exception/error is catch-able in try,catch clause.
So, how can I know that which kind of exception/error will be catched by my catch clause ?
P.S.
I finnally understand the 'error' from php engine is not the 'exception' from use land code. If you want use exception to handle engine 'error', you should manually wrap all 'error' in exception.
If you want to throw an Exception in the event that a class does not exist it, you could use class_exists().
A naive example might look something like:
function createClass($class)
{
if (!class_exists($class)) {
throw new Exception(
sprintf('Class %s does not exist', $class)
);
}
return new $class;
}
try {
$asdfasdfasdf = createClass('Asdfasdfasdf');
} catch (Exception $e) {
echo $e->getMessage();
}
From my experience, most PHP frameworks throw some sort of exception when a class is not found - for example, Symfony2 throws a ClassNotFoundException. That said, I don't know if you can 'catch' that, it's probably really just a development aid.
PHP 7 has just been released and from what I understand from the spec, you will be able to catch a fatal error as an EngineException. I don't know if it would work for your example; I haven't tested it because I have not installed PHP 7 stable yet. I tried your example with an alpha release of PHP 7 on an online REPL, and it appears that it does not work.
However for completeness, here's an example from the RFC:
function call_method($obj) {
$obj->method();
}
try {
call_method(null); // oops!
} catch (EngineException $e) {
echo "Exception: {$e->getMessage()}\n";
}
// Exception: Call to a member function method() on a non-object
In any case, as noted by #MarkBaker and #MarcB in the question's comments, you cannot "catch" a fatal error in previous versions of PHP.
Hope this helps :)
I have a script that scrapes some old HTML. It does about 1000 pages a day, and every so often it chokes for some reason and throws up the following error:
PHP Catchable fatal error: Argument 1 passed to DOMXPath::__construct() must be an instance of DOMDocument, null given, called in /var/scraper/autotrader/inc/QueryPath/QueryPath/CSS/DOMTraverser.php on line 417 and defined in /var/scraper/autotrader/inc/QueryPath/QueryPath/CSS/DOMTraverser.php on line 467
At first I thought it was the error was generated when htmlqp($html) was called, but I have wrapped it in a try{} statement and it didnt catch anything:
UPDATE:
I've found the offending line of code by using # to see when the script would terminate without error. It's this line:
try {
$items = $html->find('.searchResultHeader')->find('.vehTitle'); //this one
} catch (Exception $e) {
var_dump(get_class($e));
echo 'big dump'.$e->getTraceAsString();
}
When it bombs out, it doesn't even echo 'big dump', so it really doesn't seem to be catching it.
I'm wondering if this is maybe a fault with QueryPath's error handling rather than my own?
This:
$html->find('.searchResultHeader')->find('.vehTitle');
is the same as this:
$html->find('.searchResultHeader .vehTitle');
But without the risk of calling null->find();
If you really want to do it in 2 steps, use an if, not a try:
if($el = $html->find('.searchResultHeader')) $items = $el->find('.vehTitle');
Or maybe a ternary:
$items = ($el = $html->find('.searchResultHeader')) ? $el->find('.vehTitle') : null;
It is not catching because a standard try catch block will not catch errors of this type. In order to catch a 'Catchable' fatal error a Set Error Handler for the E_RECOVERABLE_ERROR is needed.
See Also: How can I catch a “catchable fatal error” on PHP type hinting?.
I got a try-catch block in my php application like this:
try {
if ($userForgotToEnterField) {
throw new Exception('You need to fill in your name!');
}
...
doDifferentThingsThatCanThrowExceptions();
...
} catch (ExpectedException $e) {
$template->setError('A database error occured.');
} catch (Exception $e) {
$template->setError($e->getMessage());
}
I would like to only output $e->getMessage() for the exceptions I have manually thrown with a custom error text and not the ones that have been thrown by the other code as these might contain sensitive information or very technical info that the user should not see.
Is it possible to differentiate from a manually thrown exception and a random exception thrown by some method without using a custom exception class?
I agree that it might be best to just write your own exceptions. If for whatever reason you don't want to, you could set a custom error message and a custom error code (the second parameter for the Exception constructor.) Check each thrown Exception if the error code is yours, and display only those:
public Exception::__construct() ([ string $message = "" [,int $code = 0[, Exception $previous = NULL ]]] )
and then use getCode
I've thought about this a bit and I'd say that what you are doing DOES call for a custom exception class. If you want to get around it (which in the end is going to be more confusing), you would basically create a global (or same-scope) variable that all exceptions can modify, and in your throw block flag it.
$threwCustomException = false;
try {
if ($userForgotToEnterField) {
throw new Exception('You need to fill in your name!');
$threwCustomException = true;
}
...
doDifferentThingsThatCanThrowExceptions();
...
} catch (ExpectedException $e) {
$template->setError('A database error occured.');
} catch (Exception $e) {
if($threwCustomException){
//Whatever custom exception handling you wanted here....
}
$template->setError($e->getMessage());
}
That's the best I can think of. However, this is a bad idea, and it's the whole reason you are allowed to create your own exception classes. I know you're not looking for this answer, but since you look like you're trying not to create a TON of extra code, I would just extend Exception to "CustomException" or some other name specific to your project, and throw that for all cases, and handle it that way.
Hope that helps.