How to catch Exceptions correctly in PHP and MongoDB - php

Question

My question is about the correct way to catch exceptions in PHP.
Based on the accompanying examples of the PHP MongoDB driver, I
have created the following script:
<?php
try {
$mng = new MongoDB\Driver\Manager("mongodb://localhost:2717");
$query = new MongoDB\Driver\Query([], ['sort' => [ 'name' => 1], 'limit' => 5]);
$rows = $mng->executeQuery("testdb.cars", $query);
foreach ($rows as $row) {
echo "$row->name : $row->price\n";
}
} catch (MongoDB\Driver\Exception\Exception $e) {
$filename = basename(__FILE__);
echo "The $filename script has experienced an error.\n";
echo "It failed with the following exception:\n";
echo "Exception:", $e->getMessage(), "\n";
echo "In file:", $e->getFile(), "\n";
echo "On line:", $e->getLine(), "\n";
}
?>
The example is educational and meant to be run on the PHP CLI. In PHP CLI, we get all the exceptions on the console, but for didactic purposes, I wanted to catch exceptions in the try/catch block.
I have seen more Java code than PHP and therefore, catching a generic MongoDB\Driver\Exception\Exception does not look good to me. In Java, we catch specific exceptions and have multiple try/catch blocks for different kinds of exceptions.
The driver has the following Exceptions:
MongoDB\Driver\Exception\AuthenticationException
MongoDB\Driver\Exception\BulkWriteException
MongoDB\Driver\Exception\ConnectionException
MongoDB\Driver\Exception\ConnectionTimeoutException
MongoDB\Driver\Exception\Exception
MongoDB\Driver\Exception\ExecutionTimeoutException
MongoDB\Driver\Exception\InvalidArgumentException
MongoDB\Driver\Exception\LogicException
MongoDB\Driver\Exception\RuntimeException
MongoDB\Driver\Exception\SSLConnectionException
MongoDB\Driver\Exception\UnexpectedValueException
MongoDB\Driver\Exception\WriteException
Is this a kosher way to catch exceptions in PHP?

Answer 1

How about placing a switch statement in the catch part, and determine the exception's type with the instanceof language construct or the get_class() function?
For example:
[...]
} catch(\Exception $e) {
switch (get_class($e)) {
case 'MongoDB\Driver\Exception\AuthenticationException':
// do stuff
break;
case 'MongoDB\Driver\Exception\BulkWriteException':
//etc, etc...
}
}
At first, I would examine the return values of get_class(), to make sure you I'm comparing the result with the exact exception names.

Answer 2

You can add multiple catch statements
<?php
try {
$mng = new MongoDB\Driver\Manager("mongodb://localhost:2717");
$query = new MongoDB\Driver\Query([], ['sort' => [ 'name' => 1], 'limit' => 5]);
$rows = $mng->executeQuery("testdb.cars", $query);
foreach ($rows as $row) {
echo "$row->name : $row->price\n";
}
} catch (MongoDB\Driver\Exception\AuthenticationException $e) {
echo "Exception:", $e->getMessage(), "\n";
} catch (MongoDB\Driver\Exception\ConnectionException $e) {
echo "Exception:", $e->getMessage(), "\n";
} catch (MongoDB\Driver\Exception\ConnectionTimeoutException $e) {
echo "Exception:", $e->getMessage(), "\n";
}
?>

Answer 3

Adding multiple catch statement I think it's a better approach than switch. However, what if the exception isn't from these classes with a switch you should have a default case and also if you do it with multiple catches.
try {
$mng = new MongoDB\Driver\Manager("mongodb://localhost:2717");
$query = new MongoDB\Driver\Query([], ['sort' => [ 'name' => 1], 'limit' => 5]);
$rows = $mng->executeQuery("testdb.cars", $query);
foreach ($rows as $row) {
echo "$row->name : $row->price\n";
}
} catch (MongoDB\Driver\Exception\AuthenticationException $e) {
echo "AuthenticationException:", $e->getMessage(), "\n";
} catch (MongoDB\Driver\Exception\ConnectionException $e) {
echo "ConnectionException:", $e->getMessage(), "\n";
} catch (MongoDB\Driver\Exception\ConnectionTimeoutException $e) {
echo "ConnectionTimeoutException:", $e->getMessage(), "\n";
}catch (\Exception $e) {
echo "Exception:", $e->getMessage(), "\n";
}