README

Windwalker Middleware is a simple & elegant PHP Middleware library help you integrating middleware pattern in your project.

Installation via Composer

Add this to the require block in your composer.json.

{
    "require": {
        "windwalker/middleware": "~3.0"
    }
}

Getting Started

Basic Example

This is a simple way using middleware to wrap your logic.

use Windwalker\Middleware\CallbackMiddleware;
use Windwalker\Middleware\AbstractMiddleware;

class TestA extends AbstractMiddleware
{
	/**
	 * call
	 *
	 * @return  mixed
	 */
	public function call()
	{
		echo ">>> AAAA\n";

		$this->next->call();

		echo "<<< AAAA\n";
	}
}

class TestB extends AbstractMiddleware
{
	/**
	 * call
	 *
	 * @return  mixed
	 */
	public function call()
	{
		echo ">>> BBBB\n";

		$this->next->call();

		echo "<<< BBBB\n";
	}
}

$a = new TestA;

$a->setNext(new TestB);

$a->call();

The result should be:

>>> AAAA
>>> BBBB
<<< BBBB
<<< AAAA

Callback Middleware

If you don't want to create a class, you want to set a middleware in runtime, using CallbackMiddleware

$a = new TestA;
$b = new TestB;

$a->setNext($b);
$b->setNext(new CallbackMiddleware(
	function($next)
	{
		echo ">>>CCCC\n";
		echo "<<<CCCC\n";
	}
));

$a->call();

The result should be:

>>> AAAA
>>> BBBB
>>> CCCC
<<< CCCC
<<< BBBB
<<< AAAA

The CallbackMiddleware support second argument as next in constructor:

$ware = new CallbackMiddleware(
	function($next)
	{
		echo ">>>CCCC\n";

		$next->call();

		echo "<<<CCCC\n";
	},
	new NextMiddleware
)

End The Chaining

If a middleware call next, we have to make sure there are a next middleware exists, or we will return error.

class TestB extends Middleware
{
	/**
	 * call
	 *
	 * @return  mixed
	 */
	public function call()
	{
		echo ">>> BBBB\n";

		$this->next->call();

		echo "<<< BBBB\n";
	}
}

$b = new TestB;

$b->call();

// Error, next not exists.

But yes we can set a blackhole middleware in the last element, that will do nothing when previous class call it, using EndMiddleware:

$b = new TestB;

$b->setNext(new EndMiddleware);

$b->call();

The result still like below:

>>> BBBB
<<< BBBB

Chaining Builder

We can using ChainBuilder to chaining multiple middlewares.

use Windwalker\Middleware\Chain\ChainBuilder;

$chain = new ChainBuilder;

$chain
    ->add('TestA')
    ->add(new TestB)
    ->add(function($next)
    {
        echo ">>>CCCC\n";
        echo "<<<CCCC\n";
    });

$chain->call();

The result still:

>>> AAAA
>>> BBBB
>>> CCCC
<<< CCCC
<<< BBBB
<<< AAAA

Psr7 Middleware

use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use Windwalker\Middleware\Chain\Psr7ChainBuilder;
use Windwalker\Middleware\Psr7Middleware;

class MyPsr7Middleware implements \Windwalker\Middleware\Psr7InvokableInterface
{
	public function __invoke(ServerRequestInterface $request, ResponseInterface $response, $next = null)
	{
		// Do something

		$result = $next($request, $response);

		// Do something

		return $result;
	}
}

$mid = new Psr7Middleware(function (ServerRequestInterface $request, ResponseInterface $response, $next = null)
{
	// Do something
});

$chain = new Psr7ChainBuilder;
$chain->add(new MyPsr7Middleware)
	->add($mid);

$chain->execute(new ServerRequest, new Response);

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