112 lines
3.5 KiB
ReStructuredText
112 lines
3.5 KiB
ReStructuredText
Dependency Injection
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====================
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WellRESTed strives to play nicely with other code and not force developers into using any specific libraries or frameworks. As such, WellRESTed does not provide a dependency injection container, nor does it require you to use a specific container (or any).
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This section describes a handful of ways of making the dependency container of your choice available to middleware with WellRESTed.
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Request Attribute
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^^^^^^^^^^^^^^^^^
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``Psr\Http\Message\ServerRequestInterface`` provides "attributes" that allow you attach arbitrary data to a request. You can use this to make your dependency container available to any dispatched middleware.
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When you instantiate a ``WellRESTed\Server``, you can provide an array of attributes that the server will add to the request.
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.. code-block:: php
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$container = new MySuperCoolDependencyContainer();
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$server = new WellRESTed\Server(["container" => $container]);
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// ... Add middleware, routes, etc. ...
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When the server dispatches middleware, the middleware will be able to read the container as the "container" attribute.
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.. code-block:: php
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function ($request, $response, $next) {
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$container = $request->getAttribute("container");
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// It's a super cool dependency container!
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}
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Callables
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^^^^^^^^^
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Another approach is to use callables that return ``MiddlewareInterface`` instances when you assign middleware. This approach provides an opportunity to pass the container into the middleware's constructor.
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.. code-block:: php
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Class CatHandler implements WellRESTed\MiddlewareInterface
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{
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private $container;
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public function __construct($container)
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{
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$this->container = $container;
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}
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public function __invoke(ServerRequestInterface $request, ResponseInterface $response, $next);
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{
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// Do something with the $this->container, and make a response.
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// ...
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return $response;
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}
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}
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When you add the middleware to the server or register it with a router, use a callable that passes container into the constructor.
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.. code-block:: php
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$container = new MySuperCoolDependencyContainer();
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$catHandler = function () use ($container) {
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return new CatHandler($container);
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}
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$server = new Server();
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$server->add(
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$server->createRoute()
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->register("GET", "/cats/{cat}", $catHandler)
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);
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$server->respond();
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For extra fun, store the callable that provides the handler in the container. Here's an example using Pimple_).
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.. code-block:: php
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$c = new Pimple\Container();
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$c["catHandler"] = $c->protect(function () use ($c) {
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return new CatHandler($c);
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});
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$server = new Server();
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$server->add(
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$server->createRoute()
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->register("GET", "/cats/{cat}", $c["catHandler"])
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);
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$server->respond();
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Combined
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^^^^^^^^
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Of course these two approaches are not mutually exclusive. You can even obtain your server from the container as well, for good measure.
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.. code-block:: php
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$c = new Pimple\Container();
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$c["server"] = function ($c) {
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return new Server(["container" => $c);
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};
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$c["catHandler"] = $c->protect(function () use ($c) {
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return new CatHandler($c);
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});
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$server = $c["server"];
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$server->add(
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$server->createRoute()
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->register("GET", "/cats/{cat}", $c["catHandler"])
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);
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$server->respond();
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.. _Pimple: http://pimple.sensiolabs.org
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