The Symfony container graph

We may sometimes forget about the fact that we have classes all over the place in our PHP/Symfony projects.

The most important thing is to be able to correctly represent ourselves the hierarchy of the classes themselves.

I created a small dumper that uses the native GraphvizDumper from the Symfony DependencyInjection component, because I have been curious about finding a way to make a graph about all the classes I use.

Fortunately, this dumper has been built-in for a while, it’s just not widely used, but it’s really interesting to see what becomes of our container in terms of graphs.

First, let’s use the `GraphvizDumper`

If you want to use this dumper, it’s easy! (I know we shouldn’t say “easy” in such posts, but, well, I really think it’s easy…)

I’m considering you use Symfony with the Flex architecture (so 3.3+ or 4.0+).

In src/Kernel.php, add these lines at the bottom of the configureContainer() method:

protected function configureContainer(ContainerBuilder $container, LoaderInterface $loader)
{
    // ...

    // Execute this pass after ALL other passes, so the container can be dumped when asked.
    $container->setParameter('container.dumper.graphivz.enable', 'dev' === $this->environment && $this->debug);
    $container->addCompilerPass(new DumpGraphContainerPass(), 'removing', -2048);
}

And create the DumpGraphContainerPass in the src/ directory (don’t need to put it anywhere else, after all, you shouldn’t probably use this very often).

<?php

namespace App;

use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\DependencyInjection\Dumper\GraphvizDumper;

class DumpGraphContainerPass implements CompilerPassInterface
{
    public function process(ContainerBuilder $container)
    {
        $parameterEnable = 'container.dumper.graphivz.enable';
        $parameterFile = 'container.dumper.graphivz.file';

        if (!$container->hasParameter($parameterEnable)) {
            $container->setParameter($parameterEnable, false);
        }

        if (!$container->hasParameter($parameterFile)) {
            $container->setParameter($parameterFile, $container->getParameter('kernel.cache_dir').'/container.dot');
        }

        if (!$container->getParameter($parameterEnable)) {
            return;
        }

        \file_put_contents($container->getParameter($parameterFile), (new GraphvizDumper($container))->dump());
    }
}

And it’s done!

Just run your application anytime and anyhow (just running php bin/console should do the trick).

See the final graph

When you have dumped the container thanks to the above classes, you can now view it with Graphviz.

Ensure you have the dot binary available in your environment by installing Graphviz executables for your environment (I tested this on Windows, so you can use it anywhere).

Once installed, use it like this:

$ dot -Tsvg var\cache\dev\container.dot > container.svg

Open container.svg with your favourite software and enjoy!