PDO connection does not give error, nor with dummy bank

Question

I’m starting with PDO. I’m trying to connect with the bank and I can’t.

I have the following code

    $host = "localhost";
    $user = "root";
    $pass = "root";
    $dbname = "angularDB";

    try {
        $pdo = new PDO("mysql:host=localhost;dbname=angularDBB"; "root", "root", $opcoes);
        $opcoes = array(PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION);
    } catch (Exception $e) {
        echo $e->getMessage();
    }

    return $pdo;

However, no error appears... even if I put a fictitious bank name!

Answer 1

The problem to be your dsn that is incorrect dbname:angularDB should be dbname=angularDB, the problem is that the connection failure does not throw an exception so it will never be sent to the catch block even forcing the error handling like Exception.

$opcoes = array(PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION);
$pdo = new PDO("mysql:host=localhost;dbname:angularDB"; "root", "root", $opcoes);

Answer 2

Based on the source that you posted on github, in this passage :

$pdo = new PDO("mysql:host=localhost;dbname=angularDBB"; "root", "root", $opcoes);
        $opcoes = array(PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION);

First Step

First, one must change the order:

$opcoes = array(PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION);
$pdo = new PDO("mysql:host=localhost;dbname=angularDBB"; "root", "root", $opcoes);

Because when you create an instance of PDO in the variable $pdo she tries to know if the variable $opcoes is defined, and what are its values.

2nd Step

Still in this same part of the code, we have an error in the writing of the parameters. Where it should be:

$pdo = new PDO ('mysql: host= host_name; dbname= db_name;', 'db_user', 'db_pwd', [...]);

It’s like this :

$pdo = new PDO ('mysql: host= host_name; dbname= db_name'; 'db_user', 'db_pwd', [...]);
                                                         ^

There is a ; instead of a comma. Remove the ; would be enough to correct this line.

So far we have practically solved the problem, but now let’s review.

With the modifications made, if we do:

var_dump(conectar());
// Retorna: object(PDO)#1 (0) { } 

Which means there was no object return, which is why we’re trying to figure out if any that aren’t returned Boolean, You can see that by the braces.

Now, if we try to print again the value returned by the function, but this time using the echo, and using the method cast type to define the expected return type:

echo((bool)conectar());
// Retorna: 1, equivalente a true

Another observation is in this part of the code:

print_r($pdo->query('select database()')->fetch());

It is very unlikely that we will get any correct result from this, in an attempt to try to return all the existing results, because by writing the entire expression in line, we get a infinite return, see in this example, where I used the table jogos as a basis:

while($linha = $pdo->query("SELECT * FROM jogos")->fetch(PDO::FETCH_OBJ)){
            echo $linha->nome . "<br/>";    
        }

In addition to not moving the pointer once, during the selection of results in the database, prints looping infinite of the first result.

The correct would be to first perform the query, and only then return the results using the fetch, if the goal was to return all results in the table in use.

$query = $pdo->query("SELECT * FROM jogos");    
while($linha = $query->fetch(PDO::FETCH_OBJ)){
    echo $linha->nome . "<br/>";    
}   

For the case of a single result, as it is in your original example we would do the following:

$pdo->query("SELECT * FROM jogos")->fetch(PDO::FETCH_OBJ)->nome;
// fetch(tipo de retorno)
// nome é o indice que queremos retornar

The full function would look like this:

function conectar(){
    $host = "localhost";
    $user = "root";
    $pass = "root";
    $dbname = "example";
    $erro = "";

    try {
        $opcoes = array(PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION);   
        $pdo = new PDO("mysql:host=localhost;dbname=example", "root", "root", $opcoes);

        } catch (Exception $e) {
        $erro = $e->getMessage();
    }
    if($pdo){
        return $pdo->query("SELECT * FROM jogos")->fetch(PDO::FETCH_OBJ)->nome;
        // Ou usando o looping while, para retornar todos os resultados
        /*
        $query = $pdo->query("SELECT * FROM jogos");    
        while($linha = $query->fetch(PDO::FETCH_OBJ)){
           echo $linha->nome . "<br/>"; 
        }
        */
    } else {
        return $erro;   
    }

}

// Saída dos resultados
echo conectar();

Still, this function is by far the best practice for instantiating connections PDO, I recommend you look for a more appropriate way to do so.

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Some references:

How to properly set up a PDO Connection - Soen

PDO PHP Class - Culttt

PDO - PHP.net