I have various Loggers defined in my module_config. Each controller or service that needs a specific logger needs to get the logger via its factory injected.
Ideally I don't want to worry about this injection and can make the loggers gloablly accessable (without having the service locator in my service/controller). They should be lazy loaded/instanciated, only when I need them.
Is there a way to do so? I was thinking of initializers, treats or using the event manager.
I know, It sounds like having the service locator back.
Any ideas?
I guess the cleanest way is to use a controller plugin to call upon your loggers from a controller.
Implementation is pretty simple:
Create a new PHP class and have it extend Zend\Mvc\Controller\Plugin\AbstractPlugin.
It's constructor should accept the logger(s) as a dependency, and it's __invoke method can be used to "magically" retrieve a logger.
Next, create a factory for it, implementing Zend\ServiceManager\FactoryInterface and use it to inject the dependencies (i.e., the loggers)
Register the factory in your servicemanager configuration:
'controller_plugins' => array(
'factories' => array(
'Logger' => 'MyApp\Controller\Plugin\Logger',
)
),
You are then able to call it in a controller like so:
$this->logger();
(See http://lab.empirio.no/custom-controller-plugin-in-zf2.html) for more information on creating custom controller plugins.
Lazy-loading loggers can be handled by registering them as lazy services under the lazy_services key in your service_manager configuration.
As for your services, you can implement your own version of a ServiceLocator (also known as a plugin manager).
It would work a lot like the ViewHelperManager, ControllerPluginManager, ValidatorPluginManager, etc.
I won't explain how to do that as it's a lot of code and many how-to's exist on the web on how to create one.
EDIT:
As #tasmaniski noted below you could use injection based on marker interfaces using initializers (ZF2 uses this internally through the 'Aware' interfaces).
Do note that initializers are relatively slow especially when used incorrectly, i.e. as a closure in your Module.php or module.config.php file.
Also, initializers get called upon for each service fetched by the ServiceManager's get() mtehod and can thus add significant overhead.
It is however a much easier and faster solution than writing your own implementation of a plugin manager.
I have exactly the same question in my application/architecture.
So the solution was:
In the scope of Controllers, as #FuST said you have to create controller plugin. Than the logger will be available across all controllers.
In the scope of services, I you can do a "Interface Injection".
So in your Service you have to add 3 thing:
// #1 Create interface with setLogger($logger); method
class YourService implement LoggerInterface {
private $logger; // #2 Define private $logger;
// #3 Add method that you will use to inject the $logger later
public function setLogger($logger){
$this->logger = $logger;
}
}
Than create initializer and inject $logger in every class that implement the LoggerInterface.
Related
Note: as of version 2.8, Symfony provided autowire: true for service configuration, and as of version 3.3, Symfony provided alias (instead of autowire_types) to alias a concrete object to an interface for automatic dependency injection into 'controllers as services'. There's also a bundle to allow autowiring for controller 'action' methods, although I've moved away from this and have focussed more on a variation of the ADR pattern (which is, basically, a single 'action' class with an interface method and not shoving a load of actions methods within a single class which eventually makes for an architectural nightmare). This is, effectively, what I've been looking for all these years and now no longer need to 'hook-in' a decent recursive dependency injector (auryn) as the framework now handles what it should have four years previous. I'll leave this answer here in case anyone wants to trace the steps that I did to see how the kernel works and some of the options available at this level.
Note: Although this question primarily targets Symfony 3, it should also be relevant to users of Symfony 2 as the kernel logic doesn't seem to have changed much.
I want to change how controllers are instantiated in Symfony. The logic for their instantiation currently resides in HttpKernel::handle and, more specifically, HttpKernel::handleRaw. I want to replace call_user_func_array($controller, $arguments) with my own injector performing that specific line instead.
The options I have tried thus far:
Extending HttpKernel::handle with my own method and then having this called by symfony
http_kernel:
class: AppBundle\HttpKernel
arguments: ['#event_dispatcher', '#controller_resolver', '#request_stack']
The downside of this is that, because handleRaw is private, I can't extend it without hacky reflection and so I would have to copy and paste a tonne of code.
Creating and registering a new controller resolver
controller_resolver:
class: AppBundle\ControllerResolver
arguments: []
This was a fundamental misunderstanding I had so I thought I'd document it here. The resolver's job is to resolve where to find the controller as a callable. It hasn't actually been called yet. I am more than happy with how Symfony takes the routes from routes.yml and figures out the class and method to call for the controller as a callable.
Adding an event listener on kernel.request
kernel.request:
class: MyCustomRequestListener
tags:
- { name: kernel.event_listener, event: kernel.request, method: onKernelRequest, priority: 33 /** Important, we'll get to why in a minute **/ }
Taking a look at the Http Kernel Component Documentation, we can see that it has the following typical purpose:
To add more information to the Request, initialise parts of the system, or return a Response if possible (e.g. a security layer that denies access).
I figured that by creating a new listener, using my custom injector to create my controller, and then return a response in that listener, would bypass the rest of the code that instantiates the controller. This is what I want! But there's a major flaw with this:
The Symfony Profiler doesn't show up or any of that stuff, it's just my response and that's it. Dead. I found that I can switch the priority from 31 to 33 and have it switch between my code and Symfonys, and I believe this is because of the router listener priority. I feel I'm going down the wrong path here.
Listening on the kernel.controller event.
No, this allows me to change the callable that will be called by call_user_func_array(), not how the controller is actually instantiated, which is my goal.
I've documented my ideas but I'm out. How can I achieve the following?
Change how the controllers are instantiated and then executed, specifically call_user_func_array() which is in a bloody private method (thanks Symfony)
Fall back to the default controller instantiation if mine doesn't work
Allow everything else to work as expected, like the profiler loading
Be able to bundle this up with an extension for other users
Why do I want to do this?
Controllers can have many different methods for different circumstances and each method should be able to typehint for what it individually requires rather than having a constructor take all the things, some of which may not even be used depending on the controller method being executed. Controllers don't really adhere to the Single Responsibility Principle, and they're an 'object edge case'. But they are what they are.
I want to replace how controllers are created with my own recursively autowiring injector, and also how they are executed, again with recursive introspection via my injector, as the default Symfony package does not seem to have this functionality. Even with the latest "autowire" service option in Symfony 2.8+.
The controller resolver actually does two things. The first is to get the controller. The second is to get a list of arguments for a given action.
$arguments = $this->resolver->getArguments($request, $controller);
$response = call_user_func_array($controller, $arguments);
It is the getArguments method that you could override to implement your special "action method injection" functionality. You just need to determine what arguments the action method needs and return an array of them.
Based on a different question, I also think you might be misunderstanding the autowire functionality. Autowire really only applies to constructor injection. It's not going to help with action method injection.
If the getArguments does not solve your requirement then overriding the handle method is really your only option. Yes there is quite a bit of code to copy/paste from handleRaw but that is because there is quite a bit to do in there. And even if handleRaw was protected you would still have to copy/paste the code just to get at the one line you want to replace.
Why don't you return your own callable from custom ControllerResolverInterface that would instantiate Controller in a way you want and call it?
It would be basically a decorator.
You can extend Symfony\Component\HttpKernel\Controller\ControllerResolver with your own implementation of instantiateController() method, or you can implement ControllerResolverInterface from the scratch.
UPD:
When Symfony makes a call_user_func_array($controller, $arguments); call in handleRaw(), the $controller variable is what you've returned from your custom ControllerResolver. That means you can return any callable from your resolver (it can be [$this, "callController"] f.e.) and inside this callable you would create a new Controller with Auryn and call it.
UPD2:
If you're still struggling with this, I'll add an example because you might miss what I meant here.
use Symfony\Bundle\FrameworkBundle\Controller\ControllerResolver;
class AutowiringControllerResolver extends ControllerResolver
{
// ... constructor stuff; assume $injector is a part of this class
protected function createController($controller)
{
$controller = parent::createController($controller);
return function (...$arguments) use ($controller) {
// you can do with resolved $arguments whatever you want
// or you can override getArguments() method and return
// empty array to discard getArguments() functionality completely
return $this->injector->execute($controller);
};
}
protected function instantiateController($classname)
{
return $this->injector->make($classname);
}
}
Listener is too late to solve your needs, since it excludes Dependency Injection container, which is crucial to create a valid object (~= service).
You are probably looking for Controller Autowiring feature.
If that's so, you might find solution or at least inspiration in this bundle: http://www.tomasvotruba.cz/blog/2016/03/10/autowired-controllers-as-services-for-lazy-people/
It meets your needs in these points:
autowire injector
fallback to default (FrameworkBundle's) controller resolver, if not found
it also should keep all the flow working, since there are no hacks during controller resolving process
I am currently testing phalcon php for a project, and I am looking for a way to automatically inject certain classes automatically based on an implemented interface.
The Dependency Injection reference has an example where if a class implements Phalcon\DI\InjectionAwareInterface, it will automatically inject the DI into that class.
What I want to do is similar. If a class has for instance Aranea\Db\DbAdapterAware, it should automatically inject the DbAdapter in that class. I am looking for something similar to what Zend Framework 2 does (https://juriansluiman.nl/article/121/interface-injection-with-initializers-in-zend-servicemanager), where during DI config you can specify initializers like this:
'initializers' => array(
'logger' => function($service, $sm) {
if ($service instanceof LoggerAwareInterface) {
$logger = $sm->get('logger');
$service->setLogger($logger);
}
}
),
If this is not automatically possible in PhalconPHP, I was thinking of overriding the FactoryDefault class and implement it myself. What would be the right place to inject this logic? In the get* methods, or rather in the set* methods? I assume that a method is not initialized during DI initializing but on first call, so get* would sounds more appropriate?
Thanks for your advice,
Jeroen
The Dependency Injection reference has an example where if a class implements Phalcon\DI\InjectionAwareInterface, it will automatically inject the DI into that class.
That is not entirely true, what it means is that the DI gets (automatically) injected when the service is resolved given it implements this interface, the DI doesn't magically appears there just because the class implements some interface.
If a class has for instance Aranea\Db\DbAdapterAware, it should automatically inject the DbAdapter in that class.
That is sort of how it works (not technically) if your class extends the Phalcon\DI\Injectable (or implements the InjectionAwareInterface in the same way as Phalcon\DI\Injectable). Inside Injectable there is a __get magic, which returns the service from the DI if the service exists. In other words stuff get injected only in the DI, and other classes lookup for services in there.
To inject your own services you can either pass them in your configuration to the DI or extend the DI or FactoryDefault. The difference between the two is that FactoryDefault already comes preconfigured with the useful services, which you might not need though.
I assume that a method is not initialized during DI initializing but on first call, so get* would sounds more appropriate?
Yes, there is a Phalcon\DI\Service object that represents the service and resolved when called for the first time (if it's a shared service) or resolved every time (if it's not). You normally would want all your services to be shared, otherwise this often becomes a bottleneck, e.g., when resolving a non-shared database adapter, which establishes the connection every time you call it…
PS: Note, for it to work as you want it with the DbAdapter you can do a few things:
Add the adapter getter and return DI::getDefault()->getShared('db');
Extend the Phalcon\DI\Injectable and set the DI when the class is created, so it can lookup for services.
Every time you need the adapter simply get it from the DI like shown in the first option.
I'm making my own primitive MVC framework with PHP, and I'm wondering where I should load/instantiate corresponding controller dependencies?
In the constructor of each controller (tightly coupled) or inject them (loosely coupled)?
The only part of the latter that I'm not too sure of is for the dependencies to be instantiated on bootstrap level, outside of the MVC paradigm, before being injected. Not every controller uses the exact same dependencies besides the default parent ones. I would have to instantiate them all, which would also create a lot of overhead.
I've seen some existing frameworks do it like $this->load->model('model'); // CodeIgniter in the constructor, but I have no clue on why they're doing it like that.
I would suggest you inject the dependencies, so your controllers are less coupled to your framework. This will make a switch to another framework easier.
About instantiating dependencies: I suggest you use (or implement) a dependency injection container. This container should contain factories that can instantiate services.
In an ideal situation your controllers are services too (meaning they too have factories in the dependency injection container).
This way only the controller you need for a particular request will be instantiated, and therefor only its dependencies are instantiated.
When building you own framework, this means that after the routing phase (when the correct controller is known), the framework should grab that controller from the container. The container itself will make sure all dependencies that are needed will be provided.
Have a look at Pimple for an example of a simple dependency injection container.
PS: That line from CodeIgniter looks a lot like the service locator pattern. This pattern is similar to dependency injection, but does not provide full inversion of control.
Q: Where should i load/instantiate corresponding controller dependencies?
There are multiple ways.
The load and instantiation concepts are basically "before/outside" and "after/inside".
Before and outside means, that you load the file containing a class (which you want to instantiate and pass to the controller), before you load the controller.
But how do you know, what the controller needs, before loading the controller? Uh..
Dependency Description Files
A description file comes into play, describing the wiring between your controller and it's dependencies. In other words, you can see the dependencies of your controller by looking at it's dependency description file. This concept is often used by Dependency Injection tools, which analyze the object and pull the dependencies names out automatically. It's also possible to maintain such a wiring configuration file manually. But it's tedious.
Service Locator
A Service Locator is a instantiation helper for dependencies.
Basically, it contains the same information like a dependency description file, but this time in form of a registry. The link between parts of your application becomes this registry.
Both strategies introduce overhead. It's a trade-off. When you change the perspective and look at things from an application with maybe 500+ classes, then you realize that a dependency injection tool is sometimes worth it.
Manual Injection
via Constructor Injection.
After and inside means, that you load the file containing your controller and then start to care about the dependencies.
At this point the class is not instantiated, yet, but the autoloader might do it's dirty deeds behind the scene. He evaluates the use statements at the top of your controller file. The use statements declare namespaced classes, which the autoloader resolves to actuall files and loads them. You might then start to use these classes as dependencies in your controller. This is probably the easiest way to solve your problem and i strongly suggest looking into the topics autoloading with namespaces and use-statements.
When the class is instantiated, you have the following possiblities:
use might use Setter Injection or Reference Injection to set the dependencies to the object. This requires that your Constructor Dependencies are already solved or your constructor is empty.
It's possible to combine these strategies.
Q: What does this do $this->load->model('model'); // CodeIgniter?
CodeIgniter is a legacy application framework. It was created in times, when namespaced autoloading wasn't available. $this->load is a basic class loading helper. This is the opposite of an "auto"loader, (which surprise, surprise) loads things automatically.
CodeIgniters loader class is used to load various other classes, like libraries or files from the view, helpers, models or user defined stuff. This is again the concept of a registry. Here the registry just knowns where things are in your application layout and resolves them. So $this->load->model('model'); means that the modelfunction must have some piecies of information, about the position of model files in your application.
You provide a model name and the path for the file is constructed by model.
And this is exaclty what it does (except a bit of overhead): https://github.com/EllisLab/CodeIgniter/blob/develop/system/core/Loader.php#L223.
Since I'm a Symfony developer, I can only give you a reference to Symfony.
I think you should do like they are doing in Symfony by thinking about what you need in each
Controller object.
At least, you need :
a Request object
and a Model loader object that gives you every Model you need.
Create a BaseController that implements these few functions and then extend it with custom Controllers.
You can also take a look on Silex : http://silex.sensiolabs.org/ a Micro Framework
Hope it helps.
When do you say "In the constructor" you mean to pass in the conatiner and pull the dependencies from them (in the constructor)?
<?php
class SomeController
{
public function __construct($container)
{
$this->service1 = $contanier->get('service1);
}
//...
}
I advice against that, though simpler and easier you will be coupling your controllers to the container thus using a ServiceLocator instead of truly inversion of control.
If you want your controllers to be easy unit-testable you should use inversion of control:
class SomeController
{
public function __construct($service1)
{
$this->service1 = $service1;
}
//...
}
And you can even create your controller as a service inside the container:
// this uses Pimple notation, I hope you get the point
$container['controller'] = function($c) {
return SomeController($c['service1']);
}
Use proxy services to lazy load them
Also if your controllers needs more than some services and you won't be using all of them you can:
1) Use proxy services in order to lazy load the service only when they are really needed
<?php
class ProxyService
{
/**
* #var Service1Type
*/
private $actualService;
public function __construct()
{
$this->actualService = null;
}
private function initialize()
{
$this->actualService = new Service1(); // This operation may take some time thus we deferred as long as possible
}
private function isInitialized()
{
return $this->actualService === null;
}
public function someActionOnThisService()
{
if (!$this->isInitalized()) {
$this->initalize();
}
$this->actualService->someActionOnThisService();
}
There you have a simple proxy object with lazy loading. You may want to check the fantastic Proxy Manager Library if you want to go that route
2) Split your controller
If your contoller has too many dependencies, you may want to split it.
In fact you may want to read the proposal by Paul M. Jones (lead developer of Aura Framework) about MVC-Refinement, IMHO is a good read even though you may not fully agree with it.
Even if you split your controller in order to reduce the dependencies, lazy loading your dependencies is a good idea (obviously you'll have to check weather if its doable in your context: more work in order to gain more speed).
Maybe you need to define __autoload() function before you try to load the Classes which is not loaded yet. Like:
function __autoload($className) {
require "/path/to/the/class/file/$className.php";
}
My example is very very simple to auto require the file which the class definition is in.
You can also use if-else statement or switch statement in that function to fit your own situations smartly.
The __autoload() function is called when PHP doesn't find the class definition, works for new, class_exists(), call_user_method(), etc, and absolutely for your dependences/parents classes. If there is still no class definition after __autoload() is called, PHP will generate an error.
Or you can use spl_autoload_register() function instead of __autoload() more gracefully.
For more information, you might want to see:
http://php.net/manual/en/function.autoload.php
http://php.net/manual/en/function.spl-autoload-register.php
First of all, sorry for my bad English, I hope you understand what I'm saying.
Here is my problem:
Lets assume i have an MVC application including standard router, controller, model(service) layer and some kind of db connector.
Model layer depends on a db connector, controllers depends on models/services and the top-level "application" class depends on routers and controllers.
My object hierarchy looks like this:
App -> ControllerFactory -> ServiceFactory -> DAO -> DbConnection
Perhaps, written above doesn't look like best application architecture ever, but i want to focus on the other thing:
When i'm trying to instantiate an App class i should pass all dependencies to the class instantiated; class dependencies, in turn, has their own dependencies and so on.
As a result I get all hierarchy stack instantiated at once. But what if i dont need to access the database in some cases; what if some controllers are used for rendering static templates without model interaction?
I mean, what if there are some special cases when class does not require its own dependencies(and in some cases it does)? Should i inject dependencies conditionaly or something?
I'm really stuck at this point and i don't know what to do.
Update: after re-reading carefully your question, here is another advice: yes, every class has different dependencies.
Don't inject every object into every other object. For example, some services might need DAOs, so inject them. But if a service doesn't need a DAO, don't inject any DAO.
The rest of my answer is valid if you have (for example) a service that needs a DAO (and thus a DB connection) not for every method.
What you may be looking for is lazy injection.
It is the act of injecting a dependency not loaded, so that the object is loaded only if/when used.
In conrete terms, that means injecting a proxy object, that would look like and behave exactly like the original object (for example, the db connection).
Several DI container (frameworks) support this so you don't have to create proxies yourself. I'll take as an example PHP-DI (I work on that project FYI).
Here is an example using annotations:
use DI\Annotation\Inject;
class Example {
/**
* #Inject(lazy=true)
* #var My\Class
*/
protected $property;
/**
* #Inject({ "param1" = {"lazy"=true} })
*/
public function method(My\Class $param1) {
}
}
Of course if you don't want to use annotations you can use any other configuration you want (PHP, YAML, …). Here is the same example by configuring the container in pure PHP:
$container->set('Example')
->withProperty('property', 'My\Class', true)
->withMethod('method', array('param1' => array(
'name' => 'My\Class',
'lazy' => true,
)));
See more in the documentation about Lazy Injection.
Note: you may not be using a Container for now (and that's not a problem), but for tackling lazy injection this is a fair amount of work and you might need to start considering using one.
If your dependency construction is complex, simply add a new factory class that should contain all the logic to create a correct object for you.
class AppFactory(){
__construct(all params){
}
build(useDB=true){
// logic to build
if(useDB){
App = new App(new ControllerFactory(new ServiceFactory(new DAO(new DbConnection(params)))))
} else {
App = new App(new ControllerFactory(new ServiceFactory(null))))
}
return App;
}
}
I am currently building an MVC application in PHP (not using any frameworks). I am using yadif (https://github.com/beberlei/yadif) for dependency injection.
I would like to build a login module. It should be able to use adapters, for example one might be able to set that logins are authenticated using the MySql database or some LDAP directory. This setting would be done in the admin area and is stored in a database.
I imagine that I would have an abstract adapter:
<?php
abstract AbstractLoginAdapter{
abstract function login($username, $pass){}
}
I would then just implement adapters like so:
<?php
MySQLLoginAdapter extends AbstractLoginAdapter{
public function login($username, $pass){
//do stuff
}
}
That's all nice and well, but how do I create an instance of the adapter? Usually, dependencies would be injected using yadif via the constructor:
<?php
class loginController{
private $_adapter;
public function __construct(AbstractLoginAdapter $adapter){
$this->_adapter = $adapter;
}
}
However, since I don't know which concrete adapter will be injected, I can't set that in a configuration before hand. Yadif allows me to create a configuration which I then need to pass to the container:
$builder = new Yadif_Builder();
$builder->bind("loginController")
->to("loginController")
->args($SelectedLoginAdapter);
Since the application uses a front controller, a DI container is created there. It then creates a routing object etc.
In light of this, should I pass a reference of that container down to the loginController object, and then use that container to instantiate my adapter?
Or should I instantiate a new container within my loginController object and then just load in an instance of the adapter?
I would do the first: pass a reference down to your controller. You'll want to use a single Dependency Injector Container (DIC) in your application. You don't want to create a new DIC whenever you need access to it. That would lead to duplication of objects stored in the DIC.
I know this is how Symfony 2 does it. All controllers (and many other classes) implement the ContainerAware interface. That interface has a single method setContainer() that is used to pass down a reference to the DIC.
I don't know about your specific DI tool but from a DI point of view you would be specifying which type to use. The container itself is responsible for instantiating a new instance (and possibly of all the dependencies of that type as well) of the configured type.
The benefit of DI in your example would be that you could deploy exactly the same code with a different configuration with 1 installation using LDAP and the other using MySQL authentication.
Refactor type hinting ("AbstractLoginAdapter") to ("MySQLLoginAdapter").
If you call abstract class method in the new __CLASS__ // Fatal Error.