PDO does not throw exception - php

Question

I know this question has been there many times, but no answer works for me.
My PDO just doesn't throw any error... or something catch the error before me.
I'm quite new to php, and I hate to not understand simple things.
Here's my initialization code
$pdo = new PDO("mysql:host=" . $db['host'] . ";dbname=" . $db['dbname'], $db['user'], $db['pass']);
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$pdo->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
$pdo->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
and an example where I'm, for example, inserting a duplicate row with an unicity constraint (but same problem for unknown row, or any pdo exception...)
$columnString = "....";
$valueString = "....";
$sql = "INSERT INTO " . $table . " (" . $columnString . ") VALUES (" . $valueString . ")";
try {
$stmt = $this->pdo->prepare($sql);
foreach($request_data as $key => $value){
$stmt->bindValue(':' . $key,$request_data[$key]);
}
$stmt->execute();
} catch (PDOException $e) {
return null;
}
Of course, this code works well when no database problem occurs.
I'm using Slim 3 framework, and php7. Same problem with php5.
Does it have something to do with the framework? Is there other configurations ? Why the hell exceptions are not caugh?

Answer 1

First, I do not see any use clause in your code snippet when you create PDO class instance or when you catch exception PDOException. If you miss them, it may give you error as PHP can not find where they are. You need to make sure you add
use PDO;
use PDOException;
in code that refer those classes.
Second, you suppress any exception related to PDO operation by using this code.
try {
//your code
} (PDOException $e) {
return null;
}
To be able to identify the cause of any database-related error, you need to handle exception properly. You need to replace return null; to do more meaningful action to handle the error.