This page explains how Dotkernel Admin uses the dot-dependency-injection package to perform constructor injection via the #[Inject] attribute, and how to register a class in the ConfigProvider so its dependencies are resolved.
Dependency injection is a design pattern used in software development to implement inversion of control. In simpler terms, it's the act of providing dependencies for an object during instantiation.
In PHP, dependency injection can be implemented in various ways, including through constructor injection, setter injection and property injection.
Dotkernel Admin, through its dot-dependency-injection package, focuses only on constructor injection.
Dotkernel Admin comes out of the box with the dot-dependency-injection package, which provides all the functionality for injecting dependencies into any object you want.
dot-dependency-injection determines the dependencies by looking at the #[Inject] attribute, added to the constructor of a class.
Each dependency is specified as a separate parameter of the #[Inject] attribute.
For our example we will inject RouterInterface and AuthenticationServiceInterface dependencies into GetLogoutAccountHandler.
use Dot\DependencyInjection\Attribute\Inject;
class GetLogoutAccountHandler implements RequestHandlerInterface
{
#[Inject(
RouterInterface::class,
AuthenticationServiceInterface::class,
)]
public function __construct(
protected RouterInterface $router,
protected AuthenticationServiceInterface $authenticationService,
) {
}
}If your class needs the value of a specific configuration key, you can specify the path using dot notation:
config.example
The next step is to register the class in the ConfigProvider under factories using Dot\DependencyInjection\Factory\AttributedServiceFactory::class.
public function getDependencies(): array
{
return [
'factories' => [
GetLogoutAccountHandler::class => AttributedServiceFactory::class,
],
];
}That's it. When your object is instantiated from the container, it will automatically have its dependencies resolved.
Dependencies injection is available to any object within Dotkernel Admin. For example, you can inject dependencies in a service, a handler and so on, simply by registering them in the
ConfigProvider.
Q: Which type of dependency injection does Dotkernel Admin support?
A: Through the dot-dependency-injection package, Dotkernel Admin focuses only on constructor injection.
Q: How does dot-dependency-injection know which dependencies to inject?
A: It reads the #[Inject] attribute added to a class's constructor, where each dependency is listed as a separate parameter.
Q: How do I register a class so its dependencies get resolved?
A: Register the class under factories in the module's ConfigProvider, using Dot\DependencyInjection\Factory\AttributedServiceFactory::class.
Q: Can I inject a configuration value instead of a service?
A: Yes, specify the configuration key path using dot notation, for example config.example.