Templated Middleware

The primary use case for templating is within middleware, to provide templated responses. To do this, you will:

  • Inject an instance of Zend\Expressive\Template\TemplateRendererInterface into your middleware.
  • Potentially add paths to the templating instance.
  • Render a template.
  • Add the results of rendering to your response.

Injecting a TemplateRendererInterface

We encourage the use of dependency injection. As such, we recommend writing your middleware to accept the TemplateRendererInterface via either the constructor or a setter. As an example:

namespace Acme\Blog;

use Interop\Http\ServerMiddleware\DelegateInterface;
use Interop\Http\ServerMiddleware\MiddlewareInterface;
use Psr\Http\Message\ServerRequestInterface;
use Zend\Expressive\Template\TemplateRendererInterface;

class EntryMiddleware implements MiddlewareInterface
{
    private $templateRenderer;

    public function __construct(TemplateRendererInterface $renderer)
    {
        $this->templateRenderer = $renderer;
    }

    public function process(ServerRequestInterface $request, DelegateInterface $delegate)
    {
        // ...
    }
}

This will necessitate having a factory for your middleware:

namespace Acme\Blog\Container;

use Acme\Blog\EntryMiddleware;
use Psr\Container\ContainerInterface;
use Zend\Expressive\Template\TemplateRendererInterface;

class EntryMiddlewareFactory
{
    public function __invoke(ContainerInterface $container)
    {
        return new EntryMiddleware(
            $container->get(TemplateRendererInterface::class)
        );
    }
}

And, of course, you'll need to tell your container to use the factory; see the container documentation for more information on how you might accomplish that.

Consuming templates

Now that we have the templating engine injected into our middleware, we can consume it. Most often, we will want to render a template, optionally with substitutions to pass to it. This will typically look like the following:

namespace Acme\Blog;

use Interop\Http\ServerMiddleware\DelegateInterface;
use Interop\Http\ServerMiddleware\MiddlewareInterface;
use Psr\Http\Message\ServerRequestInterface;
use Zend\Diactoros\Response\HtmlResponse;
use Zend\Expressive\Template\TemplateRendererInterface;

class EntryMiddleware implements MiddlewareInterface
{
    private $templateRenderer;

    public function __construct(TemplateRendererInterface $renderer)
    {
        $this->templateRenderer = $renderer;
    }

    public function process(ServerRequestInterface $request, DelegateInterface $delegate)
    {
        // do some work...
        return new HtmlResponse(
            $this->templateRenderer->render('blog::entry', [
                'entry' => $entry,
            ])
        );
    }
}

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