Using a Factory to Create Services
Symfony's Service Container provides multiple features to control the creation of objects, allowing you to specify arguments passed to the constructor as well as calling methods and setting parameters.
However, sometimes you need to apply the factory design pattern to delegate the object creation to some special object called "the factory". In those cases, the service container can call a method on your factory to create the object rather than directly instantiating the class.
Static Factories
Suppose you have a factory that configures and returns a new NewsletterManager
object by calling the static createNewsletterManager()
method:
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// src/Email/NewsletterManagerStaticFactory.php
namespace App\Email;
// ...
class NewsletterManagerStaticFactory
{
public static function createNewsletterManager(): NewsletterManager
{
$newsletterManager = new NewsletterManager();
// ...
return $newsletterManager;
}
}
To make the NewsletterManager
object available as a service, use the
factory
option to define which method of which class must be called to
create its object:
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# config/services.yaml
services:
# ...
App\Email\NewsletterManager:
# the first argument is the class and the second argument is the static method
factory: ['App\Email\NewsletterManagerStaticFactory', 'createNewsletterManager']
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<!-- config/services.xml -->
<?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\Email\NewsletterManager">
<!-- the first argument is the class and the second argument is the static method -->
<factory class="App\Email\NewsletterManagerStaticFactory" method="createNewsletterManager"/>
</service>
</services>
</container>
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// config/services.php
namespace Symfony\Component\DependencyInjection\Loader\Configurator;
use App\Email\NewsletterManager;
use App\Email\NewsletterManagerStaticFactory;
return function(ContainerConfigurator $container) {
$services = $container->services();
$services->set(NewsletterManager::class)
// the first argument is the class and the second argument is the static method
->factory([NewsletterManagerStaticFactory::class, 'createNewsletterManager']);
};
Note
When using a factory to create services, the value chosen for class has no effect on the resulting service. The actual class name only depends on the object that is returned by the factory. However, the configured class name may be used by compiler passes and therefore should be set to a sensible value.
Using the Class as Factory Itself
When the static factory method is on the same class as the created instance,
the class name can be omitted from the factory declaration.
Let's suppose the NewsletterManager
class has a create()
method that needs
to be called to create the object and needs a sender:
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// src/Email/NewsletterManager.php
namespace App\Email;
// ...
class NewsletterManager
{
private string $sender;
public static function create(string $sender): self
{
$newsletterManager = new self();
$newsletterManager->sender = $sender;
// ...
return $newsletterManager;
}
}
You can omit the class on the factory declaration:
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# config/services.yaml
services:
# ...
App\Email\NewsletterManager:
factory: [null, 'create']
arguments:
$sender: 'fabien@symfony.com'
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<!-- config/services.xml -->
<?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\Email\NewsletterManager">
<factory method="create"/>
</service>
</services>
</container>
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// config/services.php
namespace Symfony\Component\DependencyInjection\Loader\Configurator;
use App\Email\NewsletterManager;
return function(ContainerConfigurator $container) {
$services = $container->services();
// Note that we are not using service()
$services->set(NewsletterManager::class)
->factory([null, 'create']);
};
Non-Static Factories
If your factory is using a regular method instead of a static one to configure and create the service, instantiate the factory itself as a service too. Configuration of the service container then looks like this:
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# config/services.yaml
services:
# ...
# first, create a service for the factory
App\Email\NewsletterManagerFactory: ~
# second, use the factory service as the first argument of the 'factory'
# option and the factory method as the second argument
App\Email\NewsletterManager:
factory: ['@App\Email\NewsletterManagerFactory', 'createNewsletterManager']
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<!-- config/services.xml -->
<?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>
<!-- first, create a service for the factory -->
<service id="App\Email\NewsletterManagerFactory"/>
<!-- second, use the factory service as the first argument of the 'factory'
option and the factory method as the second argument -->
<service id="App\Email\NewsletterManager">
<factory service="App\Email\NewsletterManagerFactory"
method="createNewsletterManager"
/>
</service>
</services>
</container>
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// config/services.php
namespace Symfony\Component\DependencyInjection\Loader\Configurator;
use App\Email\NewsletterManager;
use App\Email\NewsletterManagerFactory;
return function(ContainerConfigurator $container) {
$services = $container->services();
// first, create a service for the factory
$services->set(NewsletterManagerFactory::class);
// second, use the factory service as the first argument of the 'factory'
// method and the factory method as the second argument
$services->set(NewsletterManager::class)
// In versions earlier to Symfony 5.1 the service() function was called ref()
->factory([service(NewsletterManagerFactory::class), 'createNewsletterManager']);
};
Invokable Factories
Suppose you now change your factory method to __invoke()
so that your
factory service can be used as a callback:
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// src/Email/InvokableNewsletterManagerFactory.php
namespace App\Email;
// ...
class InvokableNewsletterManagerFactory
{
public function __invoke(): NewsletterManager
{
$newsletterManager = new NewsletterManager();
// ...
return $newsletterManager;
}
}
Services can be created and configured via invokable factories by omitting the method name:
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# config/services.yaml
services:
# ...
App\Email\NewsletterManager:
class: App\Email\NewsletterManager
factory: '@App\Email\InvokableNewsletterManagerFactory'
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<!-- config/services.xml -->
<?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\Email\NewsletterManager"
class="App\Email\NewsletterManager">
<factory service="App\Email\InvokableNewsletterManagerFactory"/>
</service>
</services>
</container>
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// config/services.php
namespace Symfony\Component\DependencyInjection\Loader\Configurator;
use App\Email\NewsletterManager;
use App\Email\NewsletterManagerFactory;
return function(ContainerConfigurator $container) {
$services = $container->services();
$services->set(NewsletterManager::class)
->factory(service(InvokableNewsletterManagerFactory::class));
};
Passing Arguments to the Factory Method
Tip
Arguments to your factory method are autowired if that's enabled for your service.
If you need to pass arguments to the factory method you can use the arguments
option. For example, suppose the createNewsletterManager()
method in the
previous examples takes the templating
service as an argument:
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# config/services.yaml
services:
# ...
App\Email\NewsletterManager:
factory: ['@App\Email\NewsletterManagerFactory', createNewsletterManager]
arguments: ['@templating']
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<!-- config/services.xml -->
<?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\Email\NewsletterManager">
<factory service="App\Email\NewsletterManagerFactory" method="createNewsletterManager"/>
<argument type="service" id="templating"/>
</service>
</services>
</container>
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// config/services.php
namespace Symfony\Component\DependencyInjection\Loader\Configurator;
use App\Email\NewsletterManager;
use App\Email\NewsletterManagerFactory;
return function(ContainerConfigurator $container) {
$services = $container->services();
$services->set(NewsletterManager::class)
->factory([service(NewsletterManagerFactory::class), 'createNewsletterManager'])
->args([service('templating')])
;
};