How can I define Optional dependecies for seperate bundles? - php

Question

I will explain with an example:
There are 2 bundles : Foo\SecurityBundle and Foo\MenuBundle.
Foo\MenuBundle has Menu class that looks like this:
namespace Foo\MenuBundle;
use Foo\SecurityBundle\MenuSecurer; //note this
class Menu{
protected $securer;
public function __construct(MenuSecurer $securer = null){
$this->securer = $securer;
}
public function buildMenu(){
//build the $menu ...
//...
if($this->securer != null)
$securer->secure($menu);
}
}
the security bundle will automatically inject the $menuSecurer if it is installed,
however the problem is When the security bundle is not installed then it's classes aren't defined either, so i can't use Foo\SecurityBundle... in the MenuBundle even though I don't really use it.what's the correct way around this?

Answer 1

There is a section in the symfony docs dealing with this this situation:
http://symfony.com/doc/current/book/service_container.html#optional-dependencies-setter-injection
If you have optional dependencies for a class, then "setter injection"
may be a better option.
According to this your class might look like this:
namespace Foo\MenuBundle;
class Menu{
protected $securer;
public function setSecurer($securer) {
$this->securer = $securer;
}
public function buildMenu(){
//build the $menu ...
//...
if($this->securer != null)
$securer->secure($menu);
}
}
# config.yml
menu_service:
class: Foo\MenuBundle\Menu
calls:
- [setMailer, ["#securer"]]
Something like this...
Unfortunately you still cannot have a use statement without an interface you know is existing.

Answer 2

There are quite a few ways to go about this, but I think a good approach would be to add a configuration setting for the class/service to be injected into the constructors first argument.
For example, in the Foo\MenuBundle\Menu class (assuming this is defined as a service already), you could add an additional item to the bundle's configuration to define a default service for the $securer, then optionally override it in the config if desired.
In the configuration class (DependecyInjection\Configuration.php):
public function getConfigTreeBuilder()
{
$treeBuilder = new TreeBuilder();
$rootNode = $treeBuilder->root('foo_menu');
$rootNode
->children()
->arrayNode('service')
->addDefaultsIfNotSet()
->children()
->scalarNode('menu_securer')->defaultValue('foo_security.menu_securer')->end()
>end()
->end()
->end();
return $treeBuilder;
}
In the extension class (DependecyInjection\FooMenuExtension.php):
use Symfony\Component\DependencyInjection\Reference;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\Config\FileLocator;
use Symfony\Component\HttpKernel\DependencyInjection\Extension;
use Symfony\Component\DependencyInjection\Loader;
// ...
public function load(array $configs, ContainerBuilder $container)
{
$configuration = new Configuration();
$config = $this->processConfiguration($configuration, $configs);
$loader = new Loader\XmlFileLoader($container, new FileLocator(__DIR__.'/../Resources/config'));
// This is what sets 'foo_menu.menu_securer' to the service you want
foreach ($config['service'] as $key => $service) {
$container->setAlias($this->getAlias() . '.' . $key, $service);
}
$loader->load('services.xml');
$container->getDefinition('foo_menu.menu.menu')
->replaceArgument(0, new Reference('foo_menu.menu_securer'));
}
And your service definition would just look something like this...
<service id="foo_menu.menu.menu" class="%foo_menu.menu.menu.class%">
<argument /> <!-- foo_menu.menu_securer -->
</service>
Now in your config.yml you can just switch out the service you want to use by defining it in under...
foo_menu:
service:
menu_securer: 'some_other.service'
Edit: Regarding the type hinting, as mentioned by Markus, it would probably be a good idea to implement an interface that the $securer must implement.