PDO Connection Test - php

Question

I am writing an installer for one of my apps and I would like to be able to test some default database settings.
Is this possible using PDO to test valid and invalid database connections?
I have the following code:
try{
$dbh = new pdo('mysql:host=127.0.0.1:3308;dbname=axpdb','admin','1234');
die(json_encode(array('outcome' => true)));
}catch(PDOException $ex){
die(json_encode(array(
'outcome' => false,
'message' => 'Unable to connect'
)));
}
The problem I am having is that the script trys to connect until the script execution time of 60 seconds runs out instead of saying it cannot connect to the db.
Thanks

Answer 1

you need to set the error mode when connection to the database:
try{
$dbh = new pdo( 'mysql:host=127.0.0.1:3308;dbname=axpdb',
'admin',
'1234',
array(PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION));
die(json_encode(array('outcome' => true)));
}
catch(PDOException $ex){
die(json_encode(array('outcome' => false, 'message' => 'Unable to connect')));
}
for more infos see the following links:
Using MySQL with PDO
Errors and error handling

Answer 2

As #Sascha Galley already mentioned you should set error mode to exception mode. However, you should also set up PDO::ATTR_TIMEOUT attribute to prevent a long time waiting for response in some cases.
Although documentation says that behavior of this attribute is driver-dependent in case of MySQL it's a connection timeout. You won't find anything about it documentation but here's a short snippet from driver's source code:
long connect_timeout = pdo_attr_lval(driver_options, PDO_ATTR_TIMEOUT, 30 TSRMLS_CC);

Answer 3

As seen e.g. in the comments at this answer (but hardly anywhere else, so I made it more visible here), the "classic" PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION solution does not always work.
The implementation of PDO::ERRMODE_EXCEPTION is broken, so it seems to be "leaking" in some cases.
For example:
Warning: PDO::__construct() [pdo.--construct]: [2002] No connection could be made because the target machine actively refused
it. (trying to connect via tcp://localhost:3306) in
[...] db.php on line 34
The code there:
try {
$this->pdo = new PDO($cfg['DB'], $cfg['DB_USER'], $cfg['DB_PASS'],
array(PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION));
} catch {
echo("Can't open the database.");
}
The exception is thrown (and cought: I can see my message).
So, as a necessary workaround, you need to also put a # (let's call it a "diaper operator" in this case) before new pdo(...) to actually keep it clean.

Answer 4

There's a missing closing parenthese at the end of PDO::ERRMODE_EXCEPTION.
Should be:
$this->pdo = new PDO($cfg['DB'], $cfg['DB_USER'], $cfg['DB_PASS'],
array(PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION));