PHP catch fatal error and redirect

Question

Sometimes I get a fatal error in this line

$result = $db->execute($query);

$primary = $result->getRows();

Fatal error: Call to a member function getRows() on a non-object

I'm searching for a solution to catch this error and redirect to index page.

Rewriting something is complicated, because the system is old.

Don't try catch this, check if `$result` is an object/not boolean. — Dave Chen, May 29 '13 at 14:15
Possible duplicate: http://stackoverflow.com/questions/277224/how-do-i-catch-a-php-fatal-error/ — periklis, May 29 '13 at 14:19
not exactly, if the error can be prevented, it doesn't need to be catched — Dave Chen, May 29 '13 at 14:19

score 2 · Accepted Answer · answered May 29 '13 at 14:17

2

Something like this:

$result = $db->execute($query);

if ($result===false) {
    header("Location: errorpage.php");
    exit;
}
$primary = $result->getRows();

answered May 29 '13 at 14:17

Dave Chen

10,887
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+1 for using a guard clause instead of putting all your success logic inside a giant if statement. – BlargleMonster May 29 '13 at 14:21
I can't use header because get warning that header already send – user2413939 May 29 '13 at 14:29
Please make sure that nothing else is echo'd or displayed on the page. I wouldn't recommend, but you could use the ob_*, or echo javascript to redirect. – Dave Chen May 29 '13 at 14:34
The best method is of course NOT having any content before header. – Dave Chen May 29 '13 at 14:34

score 1 · Answer 2 · answered May 29 '13 at 14:24

In the first place, there shouldn't be an error either way.

You have to fix your code to correct the error, instead of writing new code to handle it.

Get the error message out of DB to see the certain problem that caused this error and fix it.

Also

You cannot catch a fatal error in general.
You shouldn't redirect anywhere. In case of error a '503 HTTP header' have to be returned, along with generic 503 page.

score 0 · Answer 3 · answered May 29 '13 at 14:17

The problem here is that execute() will return FALSE under some circumstances and a boolean is not the result object.

To avoid this error you should always be checking the output of execute() if it was even executed successfully.

For example:

$result = $db->execute($query);

if ($result !=== false) {
 $primary = $result->getRows();
}

score 0 · Answer 4 · answered May 29 '13 at 14:36

We need to know what $db is, you have not included the code where $db is initialised or informed us as to what this references.

Assuming you are using the PDO library, the PDO object itself has PDO::exec() and the PDOStatement object has PDOStatement::execute(). I therefore assume $db is an instance of PDOStatement and you are calling the execute() method, which returns a boolean, false upon a failure and true upon success - it does not return an object upon success. If successful, you should then call $db->fetchAll();

if (!$db->execute($query)) {
    header("Location: error.php");
    exit;
} 

$rows = $db->fetchAll();

score 0 · Answer 5 · answered May 29 '13 at 14:51

Normally you can't catch an error... only exceptions.... luckily with PHP you can set up an error_handler that does throw exceptions. (from comments on php ErrorException page)

class ErrorHandler extends Exception {
    protected $severity;

    public function __construct($message, $code, $severity, $filename, $lineno) {
        $this->message = $message;
        $this->code = $code;
        $this->severity = $severity;
        $this->file = $filename;
        $this->line = $lineno;
    }

    public function getSeverity() {
        return $this->severity;
    }
}

function exception_error_handler($errno, $errstr, $errfile, $errline ) {
    throw new ErrorHandler($errstr, 0, $errno, $errfile, $errline);
}

set_error_handler("exception_error_handler", E_ALL);

So for your specific problem you would just do:

try{
    $result = $db->execute($query);
    $primary = $result->getRows();
} catch (ErrorHandler $e){
    header("Location: /index.php");
    exit;
}

Just saying, your class is not a "handler", maybe you should change its name. There's a built-in exception that does exactly this: http://br.php.net/errorexception — Henrique Barcelos, May 29 '13 at 15:21

score -1 · Answer 6 · answered May 29 '13 at 14:37

-1

If you get the error message "header already sent" it's because something is already outputted. For instance:

echo "hello world;";
header("Location: errorpage.php");

or:

 <?php // notice the space before <?php 
header("Location: errorpage.php");
?>

answered May 29 '13 at 14:37

Casper André Casse

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PHP catch fatal error and redirect

6 Answers6