windwalker/middleware

Windwalker Middleware package

Windwalker Middleware

Windwalker Middleware is a simple & elegant PHP Middleware library help you integrating middleware pattern in your project., _(*1)

Installation via Composer

Add this to the require block in your composer.json., _(*2)

``` json { "require": { "windwalker/middleware": "~3.0" } }, <sub>(*3)</sub>

## Getting Started

### Basic Example

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

``` php
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:, <sub>(*4)</sub>

>>> 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, <sub>(*5)</sub>

``` php $a = new TestA; $b = new TestB;, <sub>(*6)</sub>

$a->setNext($b); $b->setNext(new CallbackMiddleware( function($next) { echo ">>>CCCC\n"; echo "<<<CCCC\n"; } ));, <sub>(*7)</sub>

$a->call();, <sub>(*8)</sub>

The result should be:

AAAA BBBB CCCC <<< CCCC <<< BBBB <<< AAAA, <sub>(*9)</sub>

The `CallbackMiddleware` support second argument as next in constructor:

``` php
$ware = new CallbackMiddleware(
    function($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., <sub>(*10)</sub>

``` php class TestB extends Middleware { /** * call * * @return mixed */ public function call() { echo ">>> BBBB\n";, <sub>(*11)</sub>

    $this->next->call();

    echo "<<< BBBB\n";
}

}, <sub>(*12)</sub>

$b = new TestB;, <sub>(*13)</sub>

$b->call();, <sub>(*14)</sub>

// Error, next not exists., <sub>(*15)</sub>

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

``` php
$b = new TestB;

$b->setNext(new EndMiddleware);

$b->call();

The result still like below:, <sub>(*16)</sub>

>>> BBBB
<<< BBBB

Chaining Builder

We can using ChainBuilder to chaining multiple middlewares., <sub>(*17)</sub>

``` php use Windwalker\Middleware\Chain\ChainBuilder;, <sub>(*18)</sub>

$chain = new ChainBuilder;, <sub>(*19)</sub>

$chain ->add('TestA') ->add(new TestB) ->add(function($next) { echo ">>>CCCC\n"; echo "<<<CCCC\n"; });, <sub>(*20)</sub>

$chain->call();, <sub>(*21)</sub>

The result still:

AAAA BBBB CCCC <<< CCCC <<< BBBB <<< AAAA, <sub>(*22)</sub>

## Psr7 Middleware

``` php
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);