Template Locations

Traditionally, Symfony developers stored the application templates in the Resources/views/ directory of each bundle. Then they used the logical name to refer to them (e.g. AcmeDemoBundle:Default:index.html.twig).

But for the templates used in your application, it's much more convenient to store them in the app/Resources/views/ directory. For starters, this drastically simplifies their logical names:

Another advantage is that centralizing your templates simplifies the work of your designers. They don't need to look for templates in lots of directories scattered through lots of bundles.

Twig Extensions

Our application needs a custom md2html Twig filter so that we can transform the Markdown contents of each post into HTML.

To do this, first, install the excellent Parsedown Markdown parser as a new dependency of the project:

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$ composer require erusev/parsedown

Then, create a new Markdown service that will be used later by the Twig extension. The service definition only requires the path to the class:

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# app/config/services.yml
services:
    # ...
    markdown:
        class: AppBundle\Utils\Markdown

And the Markdown class just needs to define one single method to transform Markdown content into HTML:

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namespace AppBundle\Utils;

class Markdown
{
    private $parser;

    public function __construct()
    {
        $this->parser = new \Parsedown();
    }

    public function toHtml($text)
    {
        $html = $this->parser->text($text);

        return $html;
    }
}

Next, create a new Twig extension and define a new filter called md2html using the Twig_SimpleFilter class. Inject the newly defined markdown service in the constructor of the Twig extension:

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namespace AppBundle\Twig;

use AppBundle\Utils\Markdown;

class AppExtension extends \Twig_Extension
{
    private $parser;

    public function __construct(Markdown $parser)
    {
        $this->parser = $parser;
    }

    public function getFilters()
    {
        return array(
            new \Twig_SimpleFilter(
                'md2html',
                array($this, 'markdownToHtml'),
                array('is_safe' => array('html'))
            ),
        );
    }

    public function markdownToHtml($content)
    {
        return $this->parser->toHtml($content);
    }

    public function getName()
    {
        return 'app_extension';
    }
}

Lastly define a new service to enable this Twig extension in the app (the service name is irrelevant because you never use it in your own code):

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# app/config/services.yml
services:
    app.twig.app_extension:
        class:     AppBundle\Twig\AppExtension
        arguments: ["@markdown"]
        public:    false
        tags:
            - { name: twig.extension }