Resolving undefined type 'App\PDO' error: Fix when trying to create a PHP CRUD application profile using PDO

Question

Entire project - https://github.com/steve-davey/phpsqliteconnect (config file is outdated)

This is the configuration file:

<?php

namespace App;

class Config {
   /*** Path to sqlite file*/
    const PATH_TO_SQLITE_FILE = 'db/DeviceAssetRegister.db';

}

/* Database credentials. Assume you are running a MySQL server with default settings (user 'root', no password) */
define('DB_SERVER', 'localhost');
define('DB_USERNAME', 'root');
define('DB_PASSWORD', '');
define('DB_NAME', 'DeviceAssetRegister');
 
/* Try to connect to the MySQL database */
try{
    $pdo = new PDO("mysql:host=" . DB_SERVER . ";dbname=" . DB_NAME, DB_USERNAME, DB_PASSWORD);
    // Set PDO error mode to exception
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch(PDOException $e){
    die("Error: Unable to connect." . $e->getMessage());
}
?>

I don’t understand why there is no error in the index.php file in the above directory, but there is an error for PDO?

$pdo = new PDO('sqlite:./db/DeviceAssetRegister.db');

That’s totally fine! I even got a little popup description linking to the PHP documentation in VSC. So why are errors reported in other files? Thanks!

Answer 1

PDO is a class from the root namespace. Unless you are using the root namespace correctly (either by importing PDO or using new \PDO), PHP will run from the current namespace (i.e. App) Search for this category.