minte9
LearnRemember   PHP





Service Layer Pattern 

 
Example that simply simulate the action of sending an email by printing text.
This shows the Service Layer Pattern clearly.

You move all email logic to a dedicated class.
Controllers stay clean, emails become testable.

-------------------------------------------------

Project Folder Structure (PSR-4 Compatible)

project/
│
├── composer.json
├── vendor/                (created after composer install)
│
├── src/
│   ├── Email/
│   │   ├── GenericEmail.php
│   │   └── EmailService.php
│   │
│   └── App.php            (example controller-like file)
│
└── index.php  

-------------------------------------------------

composer install
composer dump-autoload

-------------------------------------------------

Why Not a Single EmailService?

If you put everything inside EmailService (view rendering, subject, attachments), 
you end up with a class that:
- Has too many responsibilities
- Is harder to test
- Becomes messy once you add more email types
- Is tightly coupled to the internal email-building logic

Example:
What happens when you need a weekly report email, a password reset email, etc.?

If all email-building logic lives inside EmailService, 
that class becomes a "God Class" quickly.

Generic Class 

 
namespace App\Email; 

class GenericEmail
{
    public function __construct(
        public string $to, 
        public string $subject, 
        public string $body, 
        public array $attachments) {}

    public function build(): object
    {
        // Simulate mailable object
        $mail = [
            "to" => $this->to,
            "subject" => $this->subject, 
            "body" => $this->body,
            "attachments" => $this->attachments ?? [],
        ];

        // Add attachments
        foreach($this->attachments as $path) {
            $this->attach($path);
        }

        // Return mailable
        return (object) $mail;
    }

    public function attach(string $filePath): self
    {
        $this->attachments[] = $filePath;
        return $this;
    }
}

Service 

 
namespace App\Email;

class EmailService
{
    public function send(GenericEmail $genericEmail): void
    {
        // Build email
        $email = $genericEmail->build();
        
        // Simulate sending
        echo "\n EMAIL SENT / Subject: {$email->subject} ";
        foreach ($email->attachments as $path) {
            echo " / $path";
        }

        /*
            EMAIL SENT / Subject: Welcome  / welcome_guide.pdf
            EMAIL SENT / Subject: Reset Password  / instructions.txt
        */
    }
}

Application 

 
namespace App;

use App\Email\EmailService;
use App\Email\GenericEmail;

class App
{
    public function run(): void 
    {
        $service = new EmailService();

        // Welcome email
        $service->send(new GenericEmail(
            "john@example.com",
            "Welcome",
            "Hello John, welcome!",
            ["welcome_guide.pdf"]
        ));

        // Password reset email
        $service->send(new GenericEmail(
            "john@example.com",
            "Reset Password",
            "Click this to reset password.",
            ["instructions.txt"]
        ));
    }
}

Usage Example 

 
require __DIR__ . '/vendor/autoload.php';

$app = new App\App();
$app->run();