Using a Factory to Create Services

Using a Factory to Create Services

2.6The new Symfony\Component\DependencyInjection\Definition::setFactory method was introduced in Symfony 2.6. Refer to older versions for the syntax for factories prior to 2.6.

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:

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class NewsletterManagerFactory
{
    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 NewsletterFactory::createNewsletterManager() factory method:

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    services:
        newsletter_manager:
            class:   NewsletterManager
            factory: [NewsletterManagerFactory, createNewsletterManager]
    
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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 http://symfony.com/schema/dic/services/services-1.0.xsd">
    
        <services>
            <service id="newsletter_manager" class="NewsletterManager">
                <factory class="NewsletterManagerFactory" method="createNewsletterManager" />
            </service>
        </services>
    </services>
    
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    use Symfony\Component\DependencyInjection\Definition;
    
    // ...
    $definition = new Definition('NewsletterManager');
    $definition->setFactory(array('NewsletterManagerFactory', 'createNewsletterManager'));
    
    $container->setDefinition('newsletter_manager', $definition);
    

Now, the method will be called statically. If the factory class itself should be instantiated and the resulting object's method called, configure the factory itself as a service. In this case, the method (e.g. get) should be changed to be non-static.

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    services:
        newsletter_manager.factory:
            class: NewsletterManagerFactory
        newsletter_manager:
            class:   NewsletterManager
            factory: ["@newsletter_manager.factory", createNewsletterManager]
    
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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 http://symfony.com/schema/dic/services/services-1.0.xsd">
    
        <services>
            <service id="newsletter_manager.factory" class="NewsletterManagerFactory" />
    
            <service id="newsletter_manager" class="NewsletterManager">
                <factory service="newsletter_manager.factry" method="createNewsletterManager" />
            </service>
        </services>
    </container>
    
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    use Symfony\Component\DependencyInjection\Reference;
    use Symfony\Component\DependencyInjection\Definition;
    
    // ...
    $container->register('newsletter_manager.factory', 'NewsletterManagerFactory');
    
    $newsletterManager = new Definition();
    $newsletterManager->setFactory(array(
        new Reference('newsletter_manager.factory'),
        'createNewsletterManager'
    ));
    $container->setDefinition('newsletter_manager', $newsletterManager);
    

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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    services:
        newsletter_manager.factory:
            class: NewsletterManagerFactory
    
        newsletter_manager:
            class:   NewsletterManager
            factory: ["@newsletter_manager.factory", createNewsletterManager]
            arguments:
                - "@templating"
    
  • XML
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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 http://symfony.com/schema/dic/services/services-1.0.xsd">
    
        <services>
            <service id="newsletter_manager.factory" class="NewsletterManagerFactory"/>
    
            <service id="newsletter_manager" class="NewsletterManager">
                <factory service="newsletter_manager.factory" method="createNewsletterManager"/>
                <argument type="service" id="templating"/>
            </service>
        </services>
    </container>
    
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    use Symfony\Component\DependencyInjection\Reference;
    use Symfony\Component\DependencyInjection\Definition;
    
    // ...
    $container->register('newsletter_manager.factory', 'NewsletterManagerFactory');
    
    $newsletterManager = new Definition(
        'NewsletterManager',
        array(new Reference('templating'))
    );
    $newsletterManager->setFactory(array(
        new Reference('newsletter_manager.factory'),
        'createNewsletterManager'
    ));
    $container->setDefinition('newsletter_manager', $newsletterManager);
    

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