CODEWITHSUNDEEP
phpmysqlpdo
user3511568
user3511568

Reputation: 47

PHP PDO error scope?

I've been searching and testing different approaches to fix my issue but I still can't find the damn solution. I'm new to PHP and i'm trying to teach myself working with PDO.

db.php:

<?php

$dsn = 'mysql:myHost=localhost;dbname=ewt';
$user= 'root';
$pass = '';

try {
    $pdo = new PDO($dsn, $user, $pass);
    $pdo ->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
}
catch (PDOException $e) {
    echo 'Connection failed: ' . $e->getMessage();
}

showCust.php

<?php

include_once('db.php');

try {


    $sql = "SELECT * FROM PERSOON";
    $result = $pdo->query($sql);
    while($row = $result->fetch(PDO::FETCH_ASSOC)) {
        echo $row['VOORNAAM']. ' - '. $row['NAAM']. ' - '. $row['EMAIL']. ' - '. $row['ADRES']. '<br />';
    }
    $pdo = null;
}
catch(PDOException $e) {
    echo $e->getMessage();
}

It works perfecty when I copy the db.php code in the showCust.php but I want to split the DB connection from every other file. I know it has to do something with the scope of $pdo but I just can't figure it out ...

The error i keep getting are:

Notice: Undefined variable: pdo ... line 9

Fatal error: Call to a member function query() on a non-object in ... line 9

I know the database does NOT have a pw. This is purely for test purposes.

Thanks in advance !

Upvotes: 3

Views: 139

Answers (2)

&#193;lvaro Gonz&#225;lez
&#193;lvaro Gonz&#225;lez

Reputation: 146450

I suspect you did something like this:

$pdo = new PDO...;
function foo(){
    $pdo->query(...);
}
foo();

How about this?

$pdo = new PDO...;
function foo(PDO $pdo){
    $pdo->query(...);
}
foo($pdo);

The issue can also happen the other way round:

function foo(){
    $pdo = new PDO...;
}
foo();
$pdo->query(...);

You're probably posting a simplified example here, since the code you've shared should not trigger that notice. I suggest you actually try the simplified snippets outside your project.

You've just confirmed what I said about not being the actual code ;-)

i'm using include_once(addCust.php) in another PHP file. I doubt this is a correct way of coding in PHP but still learning

Make sure the first call to include_once('addCust.php)' does not happen before the first call to include_once('db.php'); and they both take place in global scope. The notice can obviously also happen if you have this:

$pdo->query(...);
$pdo = new PDO...;

Upvotes: 0

Your Common Sense
Your Common Sense

Reputation: 157872

In essence, *_once functions in PHP are but a dirty trick. A crutch to help unsuspecting programmer to keep their code in order. But nothing goes for free.

This "once" behavior means you are running this function indeed once.
Means if you have included it once already, all the consequent calls will do... n o t h i n g.

Thus, if you used include_once for db.php earlier in the code and it was inside of a function, then $pdo variable remained local for that function, leaving global scope without $pdo variable. While when included next time, db.php weren't executed and thus you have got no $pdo at all.
However, it's just a speculation.

Other reasons could be various typos. Also make sure you are running exactly the same code you posted here. You'll be surprised by it's working flawlessly

Upvotes: 1

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