Built-in Symfony Service Tags
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Read the updated version of this page for Symfony 7.1 (the current stable version).
Service tags are the mechanism used by the DependencyInjection component to flag services that require special processing, like console commands or Twig extensions.
This article shows the most common tags provided by Symfony components, but in your application there could be more tags available provided by third-party bundles.
Run this command to display tagged services in your application:
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$ php bin/console debug:container --tags
To search for a specific tag, re-run this command with a search term:
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$ php bin/console debug:container --tag=form.type
auto_alias
Purpose: Define aliases based on the value of container parameters
Consider the following configuration that defines three different but related services:
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services:
app.mysql_lock:
class: App\Lock\MysqlLock
app.postgresql_lock:
class: App\Lock\PostgresqlLock
app.sqlite_lock:
class: App\Lock\SqliteLock
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<?xml version="1.0" encoding="UTF-8" ?>
<container xmlns="http://symfony.com/schema/dic/services"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://symfony.com/schema/dic/services
https://symfony.com/schema/dic/services/services-1.0.xsd">
<services>
<service id="app.mysql_lock"
class="App\Lock\MysqlLock"/>
<service id="app.postgresql_lock"
class="App\Lock\PostgresqlLock"/>
<service id="app.sqlite_lock"
class="App\Lock\SqliteLock"/>
</services>
</container>
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// config/services.php
namespace Symfony\Component\DependencyInjection\Loader\Configurator;
use App\Lock\MysqlLock;
use App\Lock\PostgresqlLock;
use App\Lock\SqliteLock;
return function(ContainerConfigurator $configurator) {
$services = $configurator->services();
$services->set('app.mysql_lock', MysqlLock::class);
$services->set('app.postgresql_lock', PostgresqlLock::class);
$services->set('app.sqlite_lock', SqliteLock::class);
};
Instead of dealing with these three services, your application needs a generic
app.lock
service that will be an alias to one of these services, depending on
some configuration. Thanks to the auto_alias
option, you can automatically create
that alias based on the value of a configuration parameter.
Considering that a configuration parameter called database_type
exists. Then,
the generic app.lock
service can be defined as follows:
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services:
app.mysql_lock:
# ...
app.postgresql_lock:
# ...
app.sqlite_lock:
# ...
app.lock:
tags:
- { name: auto_alias, format: "app.%database_type%_lock" }
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<?xml version="1.0" encoding="UTF-8" ?>
<container xmlns="http://symfony.com/schema/dic/services"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://symfony.com/schema/dic/services
https://symfony.com/schema/dic/services/services-1.0.xsd">
<services>
<service id="app.mysql_lock"
class="App\Lock\MysqlLock"/>
<service id="app.postgresql_lock"
class="App\Lock\PostgresqlLock"/>
<service id="app.sqlite_lock"
class="App\Lock\SqliteLock"/>
<service id="app.lock">
<tag name="auto_alias" format="app.%database_type%_lock"/>
</service>
</services>
</container>
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// config/services.php
namespace Symfony\Component\DependencyInjection\Loader\Configurator;
use App\Lock\MysqlLock;
use App\Lock\PostgresqlLock;
use App\Lock\SqliteLock;
return function(ContainerConfigurator $configurator) {
$services = $configurator->services();
$services->set('app.mysql_lock', MysqlLock::class);
$services->set('app.postgresql_lock', PostgresqlLock::class);
$services->set('app.sqlite_lock', SqliteLock::class);
$services->set('app.lock')
->tag('auto_alias', ['format' => 'app.%database_type%_lock'])
;
};
The format
option defines the expression used to construct the name of the service
to alias. This expression can use any container parameter (as usual,
wrapping their names with %
characters).
Note
When using the auto_alias
tag, it's not mandatory to define the aliased
services as private. However, doing that (like in the above example) makes
sense most of the times to prevent accessing those services directly instead
of using the generic service alias.
Note
You need to manually add the Symfony
compiler pass to the container for this feature to work.
console.command
Purpose: Add a command to the application
For details on registering your own commands in the service container, read How to Define Commands as Services.
container.hot_path
Purpose: Add to list of always needed services
This tag identifies the services that are always needed. It is only applied to
a very short list of bootstrapping services (like router
, event_dispatcher
,
http_kernel
, request_stack
, etc.). Then, it is propagated to all dependencies
of these services, with a special case for event listeners, where only listed events
are propagated to their related listeners.
It will replace, in cache for generated service factories, the PHP autoload by
plain inlined include_once
. The benefit is a complete bypass of the autoloader
for services and their class hierarchy. The result is a significant performance improvement.
Use this tag with great caution, you have to be sure that the tagged service is always used.
controller.argument_value_resolver
Purpose: Register a value resolver for controller arguments such as Request
Value resolvers implement the ArgumentValueResolverInterface and are used to resolve argument values for controllers as described here: Extending Action Argument Resolving.
data_collector
Purpose: Create a class that collects custom data for the profiler
For details on creating your own custom data collection, read the How to Create a custom Data Collector article.
doctrine.event_listener
Purpose: Add a Doctrine event listener
For details on creating Doctrine event listeners, read the Doctrine events article.
doctrine.event_subscriber
Purpose: Add a Doctrine event subscriber
For details on creating Doctrine event subscribers, read the Doctrine events article.
form.type
Purpose: Create a custom form field type
For details on creating your own custom form type, read the How to Create a Custom Form Field Type article.
form.type_extension
Purpose: Create a custom "form extension"
For details on creating Form type extensions, read the How to Create a Form Type Extension article.
form.type_guesser
Purpose: Add your own logic for "form type guessing"
This tag allows you to add your own logic to the form guessing process. By default, form guessing is done by "guessers" based on the validation metadata and Doctrine metadata (if you're using Doctrine) or Propel metadata (if you're using Propel).
See also
For information on how to create your own type guesser, see Creating a custom Type Guesser.
kernel.cache_clearer
Purpose: Register your service to be called during the cache clearing process
Cache clearing occurs whenever you call cache:clear
command. If your
bundle caches files, you should add a custom cache clearer for clearing those
files during the cache clearing process.
In order to register your custom cache clearer, first you must create a service class:
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// src/Cache/MyClearer.php
namespace App\Cache;
use Symfony\Component\HttpKernel\CacheClearer\CacheClearerInterface;
class MyClearer implements CacheClearerInterface
{
public function clear($cacheDirectory)
{
// clear your cache
}
}
If you're using the default services.yaml configuration,
your service will be automatically tagged with kernel.cache_clearer
. But, you
can also register it manually:
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services:
App\Cache\MyClearer:
tags: [kernel.cache_clearer]
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<?xml version="1.0" encoding="UTF-8" ?>
<container xmlns="http://symfony.com/schema/dic/services"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://symfony.com/schema/dic/services
https://symfony.com/schema/dic/services/services-1.0.xsd">
<services>
<service id="App\Cache\MyClearer">
<tag name="kernel.cache_clearer"/>
</service>
</services>
</container>
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use App\Cache\MyClearer;
$container
->register(MyClearer::class)
->addTag('kernel.cache_clearer')
;
kernel.cache_warmer
Purpose: Register your service to be called during the cache warming process
Cache warming occurs whenever you run the cache:warmup
or cache:clear
command (unless you pass --no-warmup
to cache:clear
). It is also run
when handling the request, if it wasn't done by one of the commands yet.
The purpose is to initialize any cache that will be needed by the application and prevent the first user from any significant "cache hit" where the cache is generated dynamically.
To register your own cache warmer, first create a service that implements the CacheWarmerInterface interface:
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// src/Cache/MyCustomWarmer.php
namespace App\Cache;
use Symfony\Component\HttpKernel\CacheWarmer\CacheWarmerInterface;
class MyCustomWarmer implements CacheWarmerInterface
{
public function warmUp($cacheDirectory)
{
// ... do some sort of operations to "warm" your cache
}
public function isOptional()
{
return true;
}
}
The isOptional()
method should return true if it's possible to use the
application without calling this cache warmer. In Symfony, optional warmers
are always executed by default (you can change this by using the
--no-optional-warmers
option when executing the command).
If you're using the default services.yaml configuration,
your service will be automatically tagged with kernel.cache_warmer
. But, you
can also register it manually:
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services:
App\Cache\MyCustomWarmer:
tags:
- { name: kernel.cache_warmer, priority: 0 }
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<?xml version="1.0" encoding="UTF-8" ?>
<container xmlns="http://symfony.com/schema/dic/services"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://symfony.com/schema/dic/services
https://symfony.com/schema/dic/services/services-1.0.xsd">
<services>
<service id="App\Cache\MyCustomWarmer">
<tag name="kernel.cache_warmer" priority="0"/>
</service>
</services>
</container>
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use App\Cache\MyCustomWarmer;
$container
->register(MyCustomWarmer::class)
->addTag('kernel.cache_warmer', ['priority' => 0])
;
Note
The priority
is optional and its value is a positive or negative integer
that defaults to 0
. The higher the number, the earlier that warmers are
executed.
Caution
If your cache warmer fails its execution because of any exception, Symfony won't try to execute it again for the next requests. Therefore, your application and/or bundles should be prepared for when the contents generated by the cache warmer are not available.
In addition to your own cache warmers, Symfony components and third-party bundles define cache warmers too for their own purposes. You can list them all with the following command:
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$ php bin/console debug:container --tag=kernel.cache_warmer
kernel.event_listener
Purpose: To listen to different events/hooks in Symfony
During the execution of a Symfony application, different events are triggered and you can also dispatch custom events. This tag allows you to hook your own classes into any of those events.
For a full example of this listener, read the Events and Event Listeners article.
Core Event Listener Reference
For the reference of Event Listeners associated with each kernel event, see the Symfony Events Reference.
kernel.event_subscriber
Purpose: To subscribe to a set of different events/hooks in Symfony
This is an alternative way to create an event listener, and is the recommended
way (instead of using kernel.event_listener
). See Events and Event Listeners.
kernel.fragment_renderer
Purpose: Add a new HTTP content rendering strategy
To add a new rendering strategy - in addition to the core strategies like
EsiFragmentRenderer
- create a class that implements
FragmentRendererInterface,
register it as a service, then tag it with kernel.fragment_renderer
.
kernel.locale_aware
4.3
The kernel.locale_aware
tag was introduced in Symfony 4.3.
Purpose: To access and use the current locale
Setting and retrieving the locale can be done via configuration or using container parameters, listeners, route parameters or the current request.
Thanks to the Translation
contract, the locale can be set via services.
To register your own locale aware service, first create a service that implements the LocaleAwareInterface interface:
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// src/Locale/MyCustomLocaleHandler.php
namespace App\Locale;
use Symfony\Contracts\Translation\LocaleAwareInterface;
class MyCustomLocaleHandler implements LocaleAwareInterface
{
public function setLocale($locale)
{
$this->locale = $locale;
}
public function getLocale()
{
return $this->locale;
}
}
If you're using the default services.yaml configuration,
your service will be automatically tagged with kernel.locale_aware
. But, you
can also register it manually:
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services:
App\Locale\MyCustomLocaleHandler:
tags: [kernel.locale_aware]
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<?xml version="1.0" encoding="UTF-8" ?>
<container xmlns="http://symfony.com/schema/dic/services"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://symfony.com/schema/dic/services
https://symfony.com/schema/dic/services/services-1.0.xsd">
<services>
<service id="App\Locale\MyCustomLocaleHandler">
<tag name="kernel.locale_aware"/>
</service>
</services>
</container>
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use App\Locale\MyCustomLocaleHandler;
$container
->register(LocaleHandler::class)
->addTag('kernel.locale_aware')
;
kernel.reset
Purpose: Clean up services between requests
During the kernel.terminate
event, Symfony looks for any service tagged
with the kernel.reset
tag to reinitialize their state. This is done by
calling to the method whose name is configured in the method
argument of
the tag.
This is mostly useful when running your projects in application servers that reuse the Symfony application between requests to improve performance. This tag is applied for example to the built-in data collectors of the profiler to delete all their information.
mime.mime_type_guesser
Purpose: Add your own logic for guessing MIME types
This tag is used to register your own MIME type guessers in case the guessers provided by the Mime component don't fit your needs.
4.3
The mime.mime_type_guesser
tag was introduced in Symfony 4.3.
monolog.logger
Purpose: To use a custom logging channel with Monolog
Monolog allows you to share its handlers between several logging channels.
The logger service uses the channel app
but you can change the
channel when injecting the logger in a service.
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services:
App\Log\CustomLogger:
arguments: ['@logger']
tags:
- { name: monolog.logger, channel: app }
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<?xml version="1.0" encoding="UTF-8" ?>
<container xmlns="http://symfony.com/schema/dic/services"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://symfony.com/schema/dic/services
https://symfony.com/schema/dic/services/services-1.0.xsd">
<services>
<service id="App\Log\CustomLogger">
<argument type="service" id="logger"/>
<tag name="monolog.logger" channel="app"/>
</service>
</services>
</container>
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use App\Log\CustomLogger;
use Symfony\Component\DependencyInjection\Reference;
$container->register(CustomLogger::class)
->addArgument(new Reference('logger'))
->addTag('monolog.logger', ['channel' => 'app']);
Tip
You can create custom channels and even autowire logging channels.
monolog.processor
Purpose: Add a custom processor for logging
Monolog allows you to add processors in the logger or in the handlers to
add extra data in the records. A processor receives the record as an argument
and must return it after adding some extra data in the extra
attribute
of the record.
The built-in IntrospectionProcessor
can be used to add the file, the
line, the class and the method where the logger was triggered.
You can add a processor globally:
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services:
Monolog\Processor\IntrospectionProcessor:
tags: [monolog.processor]
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<?xml version="1.0" encoding="UTF-8" ?>
<container xmlns="http://symfony.com/schema/dic/services"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://symfony.com/schema/dic/services
https://symfony.com/schema/dic/services/services-1.0.xsd">
<services>
<service id="Monolog\Processor\IntrospectionProcessor">
<tag name="monolog.processor"/>
</service>
</services>
</container>
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use Monolog\Processor\IntrospectionProcessor;
$container
->register(IntrospectionProcessor::class)
->addTag('monolog.processor')
;
Tip
If your service is not a callable (using __invoke()
) you can add the
method
attribute in the tag to use a specific method.
You can add also a processor for a specific handler by using the handler
attribute:
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services:
Monolog\Processor\IntrospectionProcessor:
tags:
- { name: monolog.processor, handler: firephp }
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<?xml version="1.0" encoding="UTF-8" ?>
<container xmlns="http://symfony.com/schema/dic/services"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://symfony.com/schema/dic/services
https://symfony.com/schema/dic/services/services-1.0.xsd">
<services>
<service id="Monolog\Processor\IntrospectionProcessor">
<tag name="monolog.processor" handler="firephp"/>
</service>
</services>
</container>
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use Monolog\Processor\IntrospectionProcessor;
$container
->register(IntrospectionProcessor::class)
->addTag('monolog.processor', ['handler' => 'firephp'])
;
You can also add a processor for a specific logging channel by using the
channel
attribute. This will register the processor only for the
security
logging channel used in the Security component:
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services:
Monolog\Processor\IntrospectionProcessor:
tags:
- { name: monolog.processor, channel: security }
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<?xml version="1.0" encoding="UTF-8" ?>
<container xmlns="http://symfony.com/schema/dic/services"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://symfony.com/schema/dic/services
https://symfony.com/schema/dic/services/services-1.0.xsd">
<services>
<service id="Monolog\Processor\IntrospectionProcessor">
<tag name="monolog.processor" channel="security"/>
</service>
</services>
</container>
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use Monolog\Processor\IntrospectionProcessor;
$container
->register(IntrospectionProcessor::class)
->addTag('monolog.processor', ['channel' => 'security'])
;
Note
You cannot use both the handler
and channel
attributes for the
same tag as handlers are shared between all channels.
routing.loader
Purpose: Register a custom service that loads routes
To enable a custom routing loader, add it as a regular service in one
of your configuration and tag it with routing.loader
:
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services:
App\Routing\CustomLoader:
tags: [routing.loader]
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<?xml version="1.0" encoding="UTF-8" ?>
<container xmlns="http://symfony.com/schema/dic/services"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://symfony.com/schema/dic/services
https://symfony.com/schema/dic/services/services-1.0.xsd">
<services>
<service id="App\Routing\CustomLoader">
<tag name="routing.loader"/>
</service>
</services>
</container>
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use App\Routing\CustomLoader;
$container
->register(CustomLoader::class)
->addTag('routing.loader')
;
For more information, see How to Create a custom Route Loader.
routing.expression_language_provider
Purpose: Register a provider for expression language functions in routing
This tag is used to automatically register expression function providers for the routing expression component. Using these providers, you can add custom functions to the routing expression language.
security.expression_language_provider
Purpose: Register a provider for expression language functions in security
This tag is used to automatically register expression function providers for the security expression component. Using these providers, you can add custom functions to the security expression language.
security.remember_me_aware
Purpose: To allow remember me authentication
This tag is used internally to allow remember-me authentication to work. If you have a custom authentication method where a user can be remember-me authenticated, then you may need to use this tag.
If your custom authentication factory extends AbstractFactory and your custom authentication listener extends AbstractAuthenticationListener, then your custom authentication listener will automatically have this tag applied and it will function automatically.
security.voter
Purpose: To add a custom voter to Symfony's authorization logic
When you call isGranted()
on Symfony's authorization checker, a system of "voters"
is used behind the scenes to determine if the user should have access. The
security.voter
tag allows you to add your own custom voter to that system.
For more information, read the How to Use Voters to Check User Permissions article.
serializer.encoder
Purpose: Register a new encoder in the serializer
service
The class that's tagged should implement the EncoderInterface and DecoderInterface.
For more details, see How to Use the Serializer.
serializer.normalizer
Purpose: Register a new normalizer in the Serializer service
The class that's tagged should implement the NormalizerInterface and DenormalizerInterface.
For more details, see How to Use the Serializer.
The priorities of the default normalizers can be found in the registerSerializerConfiguration() method.
swiftmailer.default.plugin
Purpose: Register a custom SwiftMailer Plugin
If you're using a custom SwiftMailer plugin (or want to create one), you
can register it with SwiftMailer by creating a service for your plugin and
tagging it with swiftmailer.default.plugin
(it has no options).
Note
default
in this tag is the name of the mailer. If you have multiple
mailers configured or have changed the default mailer name for some
reason, you should change it to the name of your mailer in order to
use this tag.
A SwiftMailer plugin must implement the Swift_Events_EventListener
interface.
For more information on plugins, see SwiftMailer's Plugin Documentation.
Several SwiftMailer plugins are core to Symfony and can be activated via different configuration. For details, see Mailer Configuration Reference (SwiftmailerBundle).
templating.helper
Purpose: Make your service available in PHP templates
4.3
The templating.helper
tag is deprecated since version 4.3 and will be
removed in 5.0; use Twig instead.
To enable a custom template helper, add it as a regular service in one
of your configuration, tag it with templating.helper
and define an
alias
attribute (the helper will be accessible via this alias in the
templates):
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services:
App\Templating\AppHelper:
tags:
- { name: templating.helper, alias: alias_name }
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<?xml version="1.0" encoding="UTF-8" ?>
<container xmlns="http://symfony.com/schema/dic/services"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://symfony.com/schema/dic/services
https://symfony.com/schema/dic/services/services-1.0.xsd">
<services>
<service id="App\Templating\AppHelper">
<tag name="templating.helper" alias="alias_name"/>
</service>
</services>
</container>
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use App\Templating\AppHelper;
$container->register(AppHelper::class)
->addTag('templating.helper', ['alias' => 'alias_name'])
;
translation.loader
Purpose: To register a custom service that loads translations
By default, translations are loaded from the filesystem in a variety of different formats (YAML, XLIFF, PHP, etc).
Now, register your loader as a service and tag it with translation.loader
:
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services:
App\Translation\MyCustomLoader:
tags:
- { name: translation.loader, alias: bin }
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<?xml version="1.0" encoding="UTF-8" ?>
<container xmlns="http://symfony.com/schema/dic/services"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://symfony.com/schema/dic/services
https://symfony.com/schema/dic/services/services-1.0.xsd">
<services>
<service id="App\Translation\MyCustomLoader">
<tag name="translation.loader" alias="bin"/>
</service>
</services>
</container>
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use App\Translation\MyCustomLoader;
$container
->register(MyCustomLoader::class)
->addTag('translation.loader', ['alias' => 'bin'])
;
The alias
option is required and very important: it defines the file
"suffix" that will be used for the resource files that use this loader.
For example, suppose you have some custom bin
format that you need to
load. If you have a bin
file that contains French translations for
the messages
domain, then you might have a file translations/messages.fr.bin
.
When Symfony tries to load the bin
file, it passes the path to your
custom loader as the $resource
argument. You can then perform any logic
you need on that file in order to load your translations.
If you're loading translations from a database, you'll still need a resource
file, but it might either be blank or contain a little bit of information
about loading those resources from the database. The file is key to trigger
the load()
method on your custom loader.
translation.extractor
Purpose: To register a custom service that extracts messages from a file
When executing the translation:update
command, it uses extractors to
extract translation messages from a file. By default, the Symfony Framework
has a TwigExtractor and a
PhpExtractor, which
help to find and extract translation keys from Twig templates and PHP files.
You can create your own extractor by creating a class that implements
ExtractorInterface
and tagging the service with translation.extractor
. The tag has one
required option: alias
, which defines the name of the extractor:
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// src/Acme/DemoBundle/Translation/FooExtractor.php
namespace Acme\DemoBundle\Translation;
use Symfony\Component\Translation\Extractor\ExtractorInterface;
use Symfony\Component\Translation\MessageCatalogue;
class FooExtractor implements ExtractorInterface
{
protected $prefix;
/**
* Extracts translation messages from a template directory to the catalog.
*/
public function extract($directory, MessageCatalogue $catalog)
{
// ...
}
/**
* Sets the prefix that should be used for new found messages.
*/
public function setPrefix($prefix)
{
$this->prefix = $prefix;
}
}
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services:
App\Translation\CustomExtractor:
tags:
- { name: translation.extractor, alias: foo }
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<?xml version="1.0" encoding="UTF-8" ?>
<container xmlns="http://symfony.com/schema/dic/services"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://symfony.com/schema/dic/services
https://symfony.com/schema/dic/services/services-1.0.xsd">
<services>
<service id="App\Translation\CustomExtractor">
<tag name="translation.extractor" alias="foo"/>
</service>
</services>
</container>
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use App\Translation\CustomExtractor;
$container->register(CustomExtractor::class)
->addTag('translation.extractor', ['alias' => 'foo']);
translation.dumper
Purpose: To register a custom service that dumps messages to a file
After a translation extractor has extracted all messages from the templates, the dumpers are executed to dump the messages to a translation file in a specific format.
Symfony already comes with many dumpers:
- CsvFileDumper
- IcuResFileDumper
- IniFileDumper
- MoFileDumper
- PoFileDumper
- QtFileDumper
- XliffFileDumper
- YamlFileDumper
You can create your own dumper by extending
FileDumper or implementing
DumperInterface and tagging
the service with translation.dumper
. The tag has one option: alias
This is the name that's used to determine which dumper should be used.
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services:
App\Translation\JsonFileDumper:
tags:
- { name: translation.dumper, alias: json }
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<?xml version="1.0" encoding="UTF-8" ?>
<container xmlns="http://symfony.com/schema/dic/services"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://symfony.com/schema/dic/services
https://symfony.com/schema/dic/services/services-1.0.xsd">
<services>
<service id="App\Translation\JsonFileDumper">
<tag name="translation.dumper" alias="json"/>
</service>
</services>
</container>
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use App\Translation\JsonFileDumper;
$container->register(JsonFileDumper::class)
->addTag('translation.dumper', ['alias' => 'json']);
twig.extension
Purpose: To register a custom Twig Extension
To enable a Twig extension, add it as a regular service in one of your
configuration and tag it with twig.extension
. If you're using the
default services.yaml configuration,
the service is auto-registered and auto-tagged. But, you can also register it manually:
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services:
App\Twig\AppExtension:
tags: [twig.extension]
# optionally you can define the priority of the extension (default = 0).
# Extensions with higher priorities are registered earlier. This is mostly
# useful to register late extensions that override other extensions.
App\Twig\AnotherExtension:
tags: [{ name: twig.extension, priority: -100 }]
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<?xml version="1.0" encoding="UTF-8" ?>
<container xmlns="http://symfony.com/schema/dic/services"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://symfony.com/schema/dic/services
https://symfony.com/schema/dic/services/services-1.0.xsd">
<services>
<service id="App\Twig\AppExtension">
<tag name="twig.extension"/>
</service>
<service id="App\Twig\AnotherExtension">
<tag name="twig.extension" priority="-100"/>
</service>
</services>
</container>
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use App\Twig\AnotherExtension;
use App\Twig\AppExtension;
$container
->register(AppExtension::class)
->addTag('twig.extension')
;
$container
->register(AnotherExtension::class)
->addTag('twig.extension', ['priority' => -100])
;
For information on how to create the actual Twig Extension class, see Twig's documentation on the topic or read the How to Write a custom Twig Extension article.
twig.loader
Purpose: Register a custom service that loads Twig templates
By default, Symfony uses only one Twig Loader -
FilesystemLoader. If you need
to load Twig templates from another resource, you can create a service for
the new loader and tag it with twig.loader
.
If you use the default services.yaml configuration, the service will be automatically tagged thanks to autoconfiguration. But, you can also register it manually:
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services:
App\Twig\CustomLoader:
tags:
- { name: twig.loader, priority: 0 }
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<?xml version="1.0" encoding="UTF-8" ?>
<container xmlns="http://symfony.com/schema/dic/services"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://symfony.com/schema/dic/services
https://symfony.com/schema/dic/services/services-1.0.xsd">
<services>
<service id="App\Twig\CustomLoader">
<tag name="twig.loader" priority="0"/>
</service>
</services>
</container>
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use App\Twig\CustomLoader;
$container
->register(CustomLoader::class)
->addTag('twig.loader', ['priority' => 0])
;
Note
The priority
is optional and its value is a positive or negative integer
that defaults to 0
. Loaders with higher numbers are tried first.
twig.runtime
Purpose: To register a custom Lazy-Loaded Twig Extension
Lazy-Loaded Twig Extensions are defined as
regular services but they need to be tagged with twig.runtime
. If you're using the
default services.yaml configuration,
the service is auto-registered and auto-tagged. But, you can also register it manually:
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services:
App\Twig\AppExtension:
tags: [twig.runtime]
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<?xml version="1.0" encoding="UTF-8" ?>
<container xmlns="http://symfony.com/schema/dic/services"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://symfony.com/schema/dic/services
https://symfony.com/schema/dic/services/services-1.0.xsd">
<services>
<service id="App\Twig\AppExtension">
<tag name="twig.runtime"/>
</service>
</services>
</container>
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use App\Twig\AppExtension;
$container
->register(AppExtension::class)
->addTag('twig.runtime')
;
validator.constraint_validator
Purpose: Create your own custom validation constraint
This tag allows you to create and register your own custom validation constraint. For more information, read the How to Create a Custom Validation Constraint article.
validator.initializer
Purpose: Register a service that initializes objects before validation
This tag provides a very uncommon piece of functionality that allows you to perform some sort of action on an object right before it's validated. For example, it's used by Doctrine to query for all of the lazily-loaded data on an object before it's validated. Without this, some data on a Doctrine entity would appear to be "missing" when validated, even though this is not really the case.
If you do need to use this tag, just make a new class that implements the
ObjectInitializerInterface interface.
Then, tag it with the validator.initializer
tag (it has no options).
For an example, see the DoctrineInitializer
class inside the Doctrine
Bridge.