Advanced Container Configuration
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Advanced Container Configuration
Marking Services as public / private
When defining services, you'll usually want to be able to access these definitions
within your application code. These services are called public
. For example,
the doctrine
service registered with the container when using the DoctrineBundle
is a public service as you can access it via:
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$doctrine = $container->get('doctrine');
However, there are use-cases when you don't want a service to be public. This is common when a service is only defined because it could be used as an argument for another service.
Note
If you use a private service as an argument to more than one other service,
this will result in two different instances being used as the instantiation
of the private service is done inline (e.g. new PrivateFooBar()
).
Simply said: A service will be private when you do not want to access it directly from your code.
Here is an example:
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services:
foo:
class: Example\Foo
public: false
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<service id="foo" class="Example\Foo" public="false" />
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$definition = new Definition('Example\Foo');
$definition->setPublic(false);
$container->setDefinition('foo', $definition);
Now that the service is private, you cannot call:
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$container->get('foo');
However, if a service has been marked as private, you can still alias it (see below) to access this service (via the alias).
Note
Services are by default public.
Aliasing
You may sometimes want to use shortcuts to access some services. You can do so by aliasing them and, furthermore, you can even alias non-public services.
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services:
foo:
class: Example\Foo
bar:
alias: foo
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<service id="foo" class="Example\Foo"/>
<service id="bar" alias="foo" />
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$definition = new Definition('Example\Foo');
$container->setDefinition('foo', $definition);
$containerBuilder->setAlias('bar', 'foo');
This means that when using the container directly, you can access the foo
service by asking for the bar
service like this:
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$container->get('bar'); // Would return the foo service
Requiring files
There might be use cases when you need to include another file just before
the service itself gets loaded. To do so, you can use the file
directive.
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services:
foo:
class: Example\Foo\Bar
file: "%kernel.root_dir%/src/path/to/file/foo.php"
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<service id="foo" class="Example\Foo\Bar">
<file>%kernel.root_dir%/src/path/to/file/foo.php</file>
</service>
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$definition = new Definition('Example\Foo\Bar');
$definition->setFile('%kernel.root_dir%/src/path/to/file/foo.php');
$container->setDefinition('foo', $definition);
Notice that Symfony will internally call the PHP function require_once which means that your file will be included only once per request.