How to use the PSR-4 autoload in my /Classes/ folder? - php

Question

I've tried multiple PSR-4 loaders, but they either don't work or I can't access the classes from another folder.
My current folder structure:
-Classes
--Config.php
--Session.php
--Frontend (folder)
---Login.php
PSR-4 Autoloader:
I tried to load all classes using the PSR-4 autoload register. I modified it slightly to my folder structure. I've given all classes the namespace Classes, but the ones in the Frotend folder has the namespace Classes\Frontend.
spl_autoload_register(function ($class) {
// project-specific namespace prefix
$prefix = 'Classes\\';
// base directory for the namespace prefix
$base_dir = __DIR__ . '/Classes/';
// does the class use the namespace prefix?
$len = strlen($prefix);
if (strncmp($prefix, $class, $len) !== 0) {
// no, move to the next registered autoloader
return;
}
// get the relative class name
$relative_class = substr($class, $len);
// replace the namespace prefix with the base directory, replace namespace
// separators with directory separators in the relative class name, append
// with .php
$file = $base_dir . str_replace('\\', '/', $relative_class) . '.php';
// if the file exists, require it
if (file_exists($file)) {
require $file;
}
});
I'm not sure if this has to do with the autoloader, but I also want to call the class from any file wherever it's located. So if I have a file in
/Frontend/templates/login-page.php
I want to be able to call the class "Classes\Frontend\Login".
Is this possible and how would I do that?

Answer 1

There are mainly two ways to get it working: The first option is to use an absolute server path (starting with a '/'), to set the base directory for your classes in your autoload function:
spl_autoload_register(function ($class) {
$prefix = 'Classes\\';
$base_dir = '/var/www/html/my_project/src/'; // your classes folder
$len = strlen($prefix);
if (strncmp($prefix, $class, $len) !== 0) {
return;
}
$relative_class = substr($class, $len);
$file = $base_dir . str_replace('\\', '/', $relative_class) . '.php';
if (file_exists($file)) {
require $file;
}
});
The better solution is, as #Félix suggested, to stick with the __DIR__ constant to keep things relative to your project folder. Absolute paths are brittle between deployments on different servers. __DIR__ refers to the directory of the file it is used in; in this case it is where you register the autoload function. Starting from this directory, you can navigate to the classes base directory, for example $base_dir = __DIR__ . '/../../src/;
Don't forget to namespace your classes:
namespace Classes;
class Foo
{
public function test()
{
echo 'Hurray';
}
}
Then use classes like this:
$foo = new Classes\Foo();
$foo->test();