Using a Factory to Create Services

Symfony2'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 object.

Suppose you have a factory that configures and returns a new NewsletterManager object:

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class NewsletterFactory
{
    public function get()
    {
        $newsletterManager = new NewsletterManager();
        
        // ...
        
        return $newsletterManager;
    }
}

To make the NewsletterManager object available as a service, you can configure the service container to use the NewsletterFactory factory class:

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parameters:
    # ...
    newsletter_manager.class: NewsletterManager
    newsletter_factory.class: NewsletterFactory
services:
    newsletter_manager:
        class:          "%newsletter_manager.class%"
        factory_class:  "%newsletter_factory.class%"
        factory_method: get

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<parameters>
    <!-- ... -->
    <parameter key="newsletter_manager.class">NewsletterManager</parameter>
    <parameter key="newsletter_factory.class">NewsletterFactory</parameter>
</parameters>

<services>
    <service id="newsletter_manager" 
             class="%newsletter_manager.class%"
             factory-class="%newsletter_factory.class%"
             factory-method="get"
    />
</services>

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use Symfony\Component\DependencyInjection\Definition;

// ...
$container->setParameter('newsletter_manager.class', 'NewsletterManager');
$container->setParameter('newsletter_factory.class', 'NewsletterFactory');

$container->setDefinition('newsletter_manager', new Definition(
    '%newsletter_manager.class%'
))->setFactoryClass(
    '%newsletter_factory.class%'
)->setFactoryMethod(
    'get'
);

When you specify the class to use for the factory (via factory_class) the method will be called statically. If the factory itself should be instantiated and the resulting object's method called (as in this example), configure the factory itself as a service:

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parameters:
    # ...
    newsletter_manager.class: NewsletterManager
    newsletter_factory.class: NewsletterFactory
services:
    newsletter_factory:
        class:            "%newsletter_factory.class%"
    newsletter_manager:
        class:            "%newsletter_manager.class%"
        factory_service:  newsletter_factory
        factory_method:   get

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<parameters>
    <!-- ... -->
    <parameter key="newsletter_manager.class">NewsletterManager</parameter>
    <parameter key="newsletter_factory.class">NewsletterFactory</parameter>
</parameters>

<services>
    <service id="newsletter_factory" class="%newsletter_factory.class%"/>
    <service id="newsletter_manager" 
             class="%newsletter_manager.class%"
             factory-service="newsletter_factory"
             factory-method="get"
    />
</services>

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use Symfony\Component\DependencyInjection\Definition;

// ...
$container->setParameter('newsletter_manager.class', 'NewsletterManager');
$container->setParameter('newsletter_factory.class', 'NewsletterFactory');

$container->setDefinition('newsletter_factory', new Definition(
    '%newsletter_factory.class%'
))
$container->setDefinition('newsletter_manager', new Definition(
    '%newsletter_manager.class%'
))->setFactoryService(
    'newsletter_factory'
)->setFactoryMethod(
    'get'
);

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parameters:
    # ...
    newsletter_manager.class: NewsletterManager
    newsletter_factory.class: NewsletterFactory
services:
    newsletter_factory:
        class:            "%newsletter_factory.class%"
    newsletter_manager:
        class:            "%newsletter_manager.class%"
        factory_service:  newsletter_factory
        factory_method:   get
        arguments:
            - "@templating"

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<parameters>
    <!-- ... -->
    <parameter key="newsletter_manager.class">NewsletterManager</parameter>
    <parameter key="newsletter_factory.class">NewsletterFactory</parameter>
</parameters>

<services>
    <service id="newsletter_factory" class="%newsletter_factory.class%"/>
    <service id="newsletter_manager" 
             class="%newsletter_manager.class%"
             factory-service="newsletter_factory"
             factory-method="get"
    >
        <argument type="service" id="templating" />
    </service>
</services>

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use Symfony\Component\DependencyInjection\Definition;

// ...
$container->setParameter('newsletter_manager.class', 'NewsletterManager');
$container->setParameter('newsletter_factory.class', 'NewsletterFactory');

$container->setDefinition('newsletter_factory', new Definition(
    '%newsletter_factory.class%'
))
$container->setDefinition('newsletter_manager', new Definition(
    '%newsletter_manager.class%',
    array(new Reference('templating'))
))->setFactoryService(
    'newsletter_factory'
)->setFactoryMethod(
    'get'
);