Containers

The Middleware Container

While the skeleton creates a general PSR-11 container in which to map all of your dependencies, this can pose problems when you are attempting to pull middleware and request handlers; you could potentially, accidentally, pull something of a different type entirely, which may not work in either context!

To prevent this from happening, we provide Zend\Expressive\MiddlewareContainer. It decorates your application container, and adds the following behavior:

• has() will return true if a service does not exist in the container, but is a class that exists.
• get():
  • will instantiate a class directly if the service does not exist, but is a class that exists.
  • decorate PSR-15 RequestHandlerInterface implementations using Zend\Stratigiliity\RequestHandlerMiddleware.
  • raise an exception if the instance to return is not a PSR-15 MiddlewareInterface implementation.

Internally, this class is used by the MiddlewareFactory and the Zend\Expressive\Middleware\LazyLoadingMiddleware class; you should never need to interact with it directly, unless the above features are of interest to you.