New in Symfony 4.2: Important deprecations

Deprecated a template directory

Contributed by
Yonel Ceruto
in #28891.

Storing the app templates in src/Resources/views/ is now deprecated. You must store them in the directory defined in the twig.default_path config option in config/packages/twig.yaml, which is templates/ by default.

Deprecated the Kernel name and the root dir

Contributed by
Fabien Potencier
in #28809 and #28810.

The KernelInterface::getName() method and the kernel.name parameter have been deprecated. There's no alternative to them because this is a concept that no longer makes sense in Symfony applications.

If you need a distinctive ID for the kernel of the application, you can use the KernelInterface::getContainerClass() method and the kernel.container_class parameter.

Similarly, the getRootDir() method and the kernel.root_dir parameter have been deprecated too. The alternative is to use the getProjectdir() and kernel.project_dir method introduced in Symfony 3.3:

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# 'root_dir' is where the Kernel class is stored (src/ by default) and
# 'project_dir' is the main project directory
services:
    _defaults:
        bind:
            # Before
            $dataDir: '%kernel.root_dir%/../var/data/'
            # After
            $dataDir: '%kernel.project_dir%/var/data/'

Deprecated some console options

We've removed the original content of this blog post section because the related change was reverted before the Symfony 4.2 release. You can keep using both the console options and the environment variables:

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# Using options to control the environment and the debug behavior
$ php bin/console command_name --env=test --no-debug

# Using env vars to control the environment and the debug behavior
$ APP_ENV=test APP_DEBUG=0 php bin/console command_name

Deprecated ContainerAwareCommand

Contributed by
Robin Chalas
in #28415.

The ContainerAwareCommand class has been deprecated. It was used in the past to create commands extending from it so they had direct access to the app service container. The alternative is to extend commands from the Command class and use proper service injection in the command constructor, as explained in the main article about the Symfony Console.

TIP: use the make:command utility provided by the MakerBundle to generate commands quickly and following the Symfony recommendations.

Deprecated the base Controller class

Contributed by
Samuel Roze
in #28243.

The base Controller class is the optional class your controllers can extend from to get access to some useful shortcut methods (such us $this->render()). This Controller class has been deprecated in favor of AbstractController.

The new AbstractController base class has the same shortcuts but it's more restrictive about services. You cannot use the $this->get() shortcut to get services. You must follow the modern practices of injecting services in your controller constructor or in the controller action.

TIP: use the make:controller utility provided by the MakerBundle to generate controllers quickly and following the Symfony recommendations.

Deprecated process commands as strings

Contributed by
Nicolas Grekas
in #27821.

Passing commands as strings to the Process class has been deprecated. The alternative is to pass an array of the command parts (name, arguments, options):

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use Symfony\Component\Process\Process;

// Before
$process = new Process('ls -l');

// After
$process = new Process(['ls', '-l']);

Deprecated tree builders without root nodes

Contributed by
Christian Flothmann
in #27476.

This deprecation won't affect directly to most developers because it's related to the configuration classes of dependency injection. However, you'll see lots of these deprecation messages because of the bundles used in your application.

Fixing this deprecation will be simple in most cases, so you may contribute a fix to your favorite third-party bundle:

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use Symfony\Component\Config\Definition\Builder\TreeBuilder;

// Before
$treeBuilder = new TreeBuilder();
$rootNode = $treeBuilder->root('acme_root');
$rootNode->...()->...()->...();

// After
$treeBuilder = new TreeBuilder('acme_root');
$treeBuilder->getRootNode()->...()->...()->...();