Overriding injected class from routing group in Slim 4? - php

Question

I have a Slim4 Application composed of several modules separated in different routing groups, like so:
$app->group('/app', function(RouteCollectorProxy $app) {
/*blah blah*/
})->add(MyMiddleWare::class);
$app->group('/api', function(RouteCollectorProxy $app) {
/*blah blah*/
})->add(MyMiddleware::class);
$app->group('/admin', function(RouteCollectorProxy $app) {
/*blah blah*/
})->add(MyMiddleware::class);
MyMiddleware receives an Interface
class MyMiddleware
{
public function __construct(IMyInterface $myServiceImplementingInterface) { /*blah blah*/ }
}
When we setup the container, we tell it which class to inject so PHP-DI know which class to construct the middleware with:
/* bootstraping */
$containerBuilder = new ContainerBuilder();
$containerBuilder->addDefinitions(__DIR__ . '/container.php');
$container = $containerBuilder->build();
and
/*container.php*/
return [
IMyInterface::class => function (ContainerInterface $container) {
return new MyServiceImplementingInterface();
},
];
My main question is:
Would it be possible to somehow override the implementation of the container setup for IMyInterface::class based on the Routing Group ? so I could have something like:
Main container setup:
/*container.php*/
return [
IMyInterface::class => function (ContainerInterface $container) {
return new MyServiceImplementingInterface();
},
];
Specific route group container setup:
/*container.admin.php*/
return [
IMyInterface::class => function (ContainerInterface $container) {
return new AnotherServiceImplementingInterface();
},
];

Answer 1

I suggest using two different objects of MyMiddleware class for different groups, each constructed using appropriate implementation of IMyInterface. You can tell PHP-DI to call the constructor with the parameters you want.
Here I created two instances of MyMiddleware, one with the name AdminMiddleware and the other named ApiMiddleware in the container. using DI\create()->constructor() method, I configure the DI to inject different implementations of IMyInterface while building these two objects:
<?php
use DI\ContainerBuilder;
use Slim\Factory\AppFactory;
// this is the path of autoload.php relative to my index.php file
// change it according to your directory structure
require __DIR__ . '/../vendor/autoload.php';
interface IMyInterface {
public function sampleMethod();
}
class MyServiceImplementingInterface implements IMyInterface {
public function sampleMethod() {
return 'This implementation is supposed to be used for API endpoint middleware';
}
}
class AnotherServiceImplementingInterface implements IMyInterface {
public function sampleMethod() {
return 'This implementation is supposed to be used for Admin middleware';
}
}
class MyMiddleware
{
private $service;
public function __construct(IMyInterface $myServiceImplementingInterface) {
$this->service = $myServiceImplementingInterface;
}
public function __invoke($request, $handler)
{
$response = $handler->handle($request);
$response->getBody()->write($this->service->sampleMethod());
return $response;
}
}
$containerBuilder = new ContainerBuilder();
$containerBuilder->addDefinitions([
'AdminMiddleware' => DI\create(MyMiddleware::class)->constructor(DI\get(AnotherServiceImplementingInterface::class)),
'ApiMiddleware' => DI\create(MyMiddleware::class)->constructor(DI\get(MyServiceImplementingInterface::class))
]);
$container = $containerBuilder->build();
AppFactory::setContainer($container);
$app = AppFactory::create();
$app->group('/admin', function($app) {
$app->get('/dashboard', function($request, $response, $args){
return $response;
});
})->add($container->get('AdminMiddleware'));
$app->group('/api', function($app) {
$app->get('/endpoint', function($request, $response, $args){
return $response;
});
})->add($container->get('ApiMiddleware'));
$app->run();