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Nimo features many traits / base classes for writing middlewares.

Base classes

AbstractHandler and AbstractMiddleware are main base class of Nimo.

They implement handle/process method by:

first remember all the params in instance property
call the abstract main method

so that all the preceding logic wouldn't need to pass $request / $handler everywhere. For middleware, a delegate method is available to call $this->handler with $this->request

In addition, they used all traits provided by Nimo so all the below features are available.

AttachToRequestTrait

Some middleware may carry useful runtime data, or function as a service to be referenced in later logic. In PSR standard, RequestInterface contains attribute mechanism to do this.

In Nimo, the AttachToRequestTrait provides ability that middleware can "attach" itself to request (attribute), so other middleware/handler can reference the instance easily.

//in FooMiddleware A's main logic
$this->attachToRequest(); // to $this->request by default, also would return the attached request instance

//later, in other place
FooMiddleware::fromRequest($request) // retrieves the FooMiddleware instance early attached

The convention is to use class name as the attribute key, so in most case, name collision is auto avoided. This can be override by define ATTR_KEY const in class.

class FooMiddleware extends AbstractMiddleware {
    const ATTR_KEY = 'foo';
}


//after attached, in other place
$request->getAttribute('foo') // the FooMiddleware instance

Wrapper methods

These methods have been introduced in before sections, so just a quick list here.

For handlers

$handler->includeMiddleware($middleware);
$handler->catch($catcher, $catchClassName);

For middlewares

// piping
$middleware->append($another)
$middleware->prepend($another)
// conditional run
$middleware->when($prediction);
$middleware->unless($prediction);
// error handling
$middleware->catch($catcher, $catchClassName);