README

Description:

This library offers interfaces and implementations for a simple command, command-handler, command-bus structure.

This is of course not an original idea, but my preferred and fairly simple implementation.

The code is fully tested, I however do not take responsibility for use in production.

Use at your own risk.

Installation:

composer require maxkaemmerer/commands

Usage:

Generally you don't want to register each CommandHandler by hand. You might want to use dependency injection via a container or service-manager.

(An example for the Symfony Framework would be using a CompilerPass)

You would also want to inject the CommandBus itself via dependency injection wherever you need it.

Feel free to create your own implementations of CommandBus and Payload if you require something more advanced.

Register a Command Handler:

Register a CommandHandler to the CommandBus. The CommandHandler's handles() method returns the name of the Command that it handles.

Best practice would be using the fully qualified class name of the command. MyCommand::class

The CommandHandler::handle($command) method is where your actual domain logic happens.

Feel free to inject services, a container, or whatever else you need, into your CommandHandlers.

$commandBus = new SimpleCommandBus();

$commandBus->registerHandler(new class implements CommandHandler
{

    /**
     * @param Command $command
     */
    public function handle(Command $command): void
    {
        echo $command->payload()->get('message');
    }

    /**
     * @return string
     * The name of the command this handler handles. Command::name()
     */
    public function handles(): string
    {
        return 'commandName';
    }

});

Dispatch a Command:

Dispatching a Command causes the CommandBus to look for a CommandHandler who's CommandHandler:handles() method matches the Command's name, specified by Command:name(), and calls it's CommandHandler::handle($command) method.

IMPORTANT: CommandHandler's and the CommandBus never return anything.

...

// The CommandHandler was registered

$commandBus->dispatch(new class implements Command
{

    /**
     * @return CommandPayload
     */
    public function payload(): CommandPayload
    {
        // You would of course set the Payload in the constructor of your Command implementation
        return Payload::fromArray(['message' => 'Hello World!']);
    }

    /**
     * @return string
     * The name of this command, it is recommended to use the fully qualified class name.
     */
    public function name(): string
    {
        return 'commandName';
    }

});

Full Example:

<?php

use MaxKaemmerer\Commands\Command;
use MaxKaemmerer\Commands\CommandHandler;
use MaxKaemmerer\Commands\CommandPayload;
use MaxKaemmerer\Commands\Exception\CommandException;
use MaxKaemmerer\Commands\Implementations\Payload;
use MaxKaemmerer\Commands\Implementations\SimpleCommandBus;

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

try {
    $commandBus = new SimpleCommandBus();

    $commandBus->registerHandler(new class implements CommandHandler
    {

        /**
         * @param Command $command
         */
        public function handle(Command $command): void
        {
            echo $command->payload()->get('message');
        }

        /**
         * @return string
         * The name of the command this handler handles. Command::name()
         */
        public function handles(): string
        {
            return 'commandName';
        }

    });

    $commandBus->dispatch(new class implements Command
    {

        /**
         * @return CommandPayload
         */
        public function payload(): CommandPayload
        {
            // You would of course set the Payload in the constructor of your Command implementation
            return Payload::fromArray(['message' => 'Hello World!']);
        }

        /**
         * @return string
         * The name of this command, it is recommended to use the fully qualified class name.
         */
        public function name(): string
        {
            return 'commandName';
        }

    });

} catch (CommandException $exception) {
    error_log($exception->getMessage());
}

Result: Hello World!