Using a Factory to Create Services
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Using a Factory to Create Services
Symfony's Service Container provides a powerful way of controlling the creation of objects, allowing you to specify arguments passed to the constructor as well as calling methods and setting parameters. Sometimes, however, this will not provide you with everything you need to construct your objects. For this situation, you can use a factory to create the object and tell the service container to call a method on the factory rather than directly instantiating the class.
Suppose you have a factory that configures and returns a new NewsletterManager
object by calling the static createNewsletterManager() method:
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class NewsletterManagerStaticFactory
{
public static function createNewsletterManager()
{
$newsletterManager = new NewsletterManager();
// ...
return $newsletterManager;
}
}To make the NewsletterManager object available as a service, you can
configure the service container to use the
NewsletterManagerStaticFactory::createNewsletterManager() factory method:
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# app/config/services.yml
services:
app.newsletter_manager:
class: AppBundle\Email\NewsletterManager
# call the static method
factory: ['AppBundle\Email\NewsletterManagerStaticFactory', createNewsletterManager]Note
When using a factory to create services, the value chosen for the class
option 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.
If your factory is not using a static function to configure and create your service, but a regular method, you can instantiate the factory itself as a service too. Later, in the "Using a Factory to Create Services" section, you learn how you can inject arguments in this method.
Configuration of the service container then looks like this:
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# app/config/services.yml
services:
app.newsletter_manager_factory:
class: AppBundle\Email\NewsletterManagerFactory
app.newsletter_manager:
class: AppBundle\Email\NewsletterManager
# call a method on the specified factory service
factory: 'app.newsletter_manager_factory:createNewsletterManager'Note
The traditional configuration syntax in YAML files used an array to define the factory service and the method name:
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# app/config/services.yml
app.newsletter_manager:
# new syntax
factory: 'app.newsletter_manager_factory:createNewsletterManager'
# old syntax
factory: ['@app.newsletter_manager_factory', createNewsletterManager]Passing Arguments to the Factory Method
If you need to pass arguments to the factory method, you can use the arguments
options inside the service container. For example, suppose the createNewsletterManager()
method in the previous example takes the templating service as an argument:
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# app/config/services.yml
services:
# ...
app.newsletter_manager:
class: AppBundle\Email\NewsletterManager
factory: 'newsletter_manager_factory:createNewsletterManager'
arguments: ['@templating']
