handler.md

Command handler

You can use any implementations of callable type as a command handler.

The command handler can be a anonymous function:

$handler = static function (RenameArticleCommand $command): void {
    // do something
};

// register command handler in handler locator
$locator = new DirectBindingCommandHandlerLocator();
$locator->registerHandler(RenameArticleCommand::class, $handler);

It can be a some function:

function RenameArticleHandler(RenameArticleCommand $command): void
{
    // do something
}

// register command handler in handler locator
$locator = new DirectBindingCommandHandlerLocator();
$locator->registerHandler(RenameArticleCommand::class, 'RenameArticleHandler');

It can be a called object:

class RenameArticleHandler
{
    public function __invoke(RenameArticleCommand $command): void
    {
        // do something
    }
}

// register command handler in handler locator
$locator = new DirectBindingCommandHandlerLocator();
$locator->registerHandler(RenameArticleCommand::class, new RenameArticleHandler());

It can be a static method of class:

class RenameArticleHandler
{
    public static function handleRenameArticle(RenameArticleCommand $command): void
    {
        // do something
    }
}

// register command handler in handler locator
$locator = new DirectBindingCommandHandlerLocator();
$locator->registerHandler(RenameArticleCommand::class, 'RenameArticleHandler::handleRenameArticle');

It can be a public method of class:

class RenameArticleHandler
{
    public function handleRenameArticle(RenameArticleCommand $command): void
    {
        // do something
    }
}

// register command handler in handler locator
$locator = new DirectBindingCommandHandlerLocator();
$locator->registerHandler(RenameArticleCommand::class, [new RenameArticleHandler(), 'handleRenameArticle']);

You can handle many commands in one handler.

class ArticleHandler
{
    public function handleRenameArticle(RenameArticleCommand $command): void
    {
        // do something
    }

    public function handlePublishArticle(PublishArticleCommand $command): void
    {
        // do something
    }
}

// register command handler in handler locator
$locator = new DirectBindingCommandHandlerLocator();
$locator->registerHandler(RenameArticleCommand::class, [new ArticleHandler(), 'handleRenameArticle']);
$locator->registerHandler(PublishArticleCommand::class, [new ArticleHandler(), 'handlePublishArticle']);

Command handler locator

You can use exists locators of command handler:

• Direct binding locator
• PSR-11 container aware locator
• Symfony container aware locator

Or you can create custom locator that implements GpsLab\Component\Command\Handler\Locator\CommandHandlerLocator interface.