How do I redefine Slim v3's error handler? - php

Question

I followed the Slim v3 documentation to a tee on how to redefine the framework's built in error handler so as to prevent errors from being outputted to the response with the following code:
$settings = require __DIR__ . '/../src/settings.php';
$app = new \Slim\App($settings);
// Errors to log rather than to end user
$c = $app->getContainer();
$c['errorHandler'] = function ($c) {
return function ($request, $response, $exception) use ($c) {
$c['logger']->error("Error 500 diverted: ".$exception->getMessage());
return $c['response']->withStatus(500)
->withHeader('Content-Type', 'text/html')
->write('Something went wrong on our side!');
};
};
And yet my API is still spitting out Slim's default handler with full stack traces and the telltale Slim Application Error string... albeit helpful, I'd much rather have this information going to Slim's log (monolog) and something less revealing facing the client. Is there any reason that this service redefinition is effectively being ignored?

Answer 1

This code works:
<?php
$app = new \Slim\App();
$container = $app->getContainer();
$container['errorHandler'] = function ($c) {
return function ($request, $response, $exception) use ($c) {
// log error here
return $c['response']->withStatus(500)
->withHeader('Content-Type', 'text/html')
->write('Something went wrong on our side!');
};
};
$container['phpErrorHandler'] = function ($c) {
return function ($request, $response, $error) use ($c) {
// log error here
return $c['response']->withStatus(500)
->withHeader('Content-Type', 'text/html')
->write('Something went wrong on our side (again)!');
};
};
$app->get('/exception', function ($req, $res, $args) {
// errorHandler will trap this Exception
throw new Exception("An error happened here");
});
$app->get('/php7', function ($req, $res, $args) {
$x = function (int $x) {
return $x;
};
// phpErrorHandler wil trap this Error
$x('test');
});
$app->get('/warning', function ($req, $res, $args) {
$x = UNDEFINED_CONSTANT;
});
$app->run();
As you can see, you need to register an errorHandler to catch Exceptions and a phpErrorHandler to catch PHP 7 Errors.
Note that neither will catch a PHP Notice as shown by the /warning route. To catch that too, you need to register your own error handler:
set_error_handler(function ($severity, $message, $file, $line) {
if (!(error_reporting() & $severity)) {
// This error code is not included in error_reporting, so ignore it
return;
}
throw new \ErrorException($message, 0, $severity, $file, $line);
});