think about this scenario:
I have a class (for example A) with this constructor. :
public function __construct(SocialChannelContract $channel, CallBackQueryDVO $message)
{
$this->message = $message;
$this->channel = $channel;
}
and this is the register method in AppServiceProvider:
$this->app->singleton(SocialChannelContract::class, MyChannel::class);
now I want to create an instance of class A.
return new A($callBackQueryDVO);
But it returns me this error that you should pass parameter 1 to class A while I introduce the class in AppServiceProvider. what is wrong in this example?
If you want to use constructor injection you need to let the service container make the class:
App::make(A::class);
app(A::class);
app()->make(A::class);
If you want to create the class manually you need to give the constructor all the arguments.
$channel = new SocialChannelContract(...); or $channel = app(SocialChannelContract::class);
Then, new A($channel, $myOtherStuff, ...)
Then
Related
In my controller I am using a class like so:
public function book($id, CalRequest $request)
{
$event = $this->repo->find($id);
(new CalAuthorisation())
->setEvent($event)
->canBook();
$this->booking->book($event, $request);
}
I'm mocking a class like below:
$auth = \Mockery::mock(CalAuthorisation::class)->makePartial();
$this->app->bind(CalAuthorisation::class, function() use ($auth) {
return $auth;
});
$auth->shouldReceive('canBook')->once()->andReturn(true);
However, if I dd within the canBook() function I still get into there. I have a similar mock in place for the CalRequest class which works fine. Any suggestions as to why this isn't working!
Dependency injection is about injecting different implementation into your logic. When using new keyword, PHP will fetch a certain class and only that class. Laravel solves dependency injection through the container, so you have to use the container for it to work.
There is two ways, either use app() or resolve(). Secondly you can inject your classes into methods that are on Laravel classes like jobs, commands, controllers etc. and this will be resolved through the container.
Using resolve().
resolve(new CalAuthorisation())
->setEvent($event)
->canBook();
Injecting it, through the controller method.
public function book($id, CalRequest $request, CalAuthorisation $calAuth)
{
$event = $this->repo->find($id);
$calAuth->setEvent($event)
->canBook();
I created an helper and I try to use it in one of my controllers,but I got an error, and I am not sure why.
//StringHelper.php
namespace App\Helpers;
class StringHelper
{
public function example($str1){
//CODE
}
}
//config/app.php
'aliases' => [
'StringHelper' => App\Helpers\StringHelper::class,
]
//In controller
use StringHelper;
$percentage = StringHelper::example($title);
Non-static method App\Helpers\StringHelper::example() should not be
called statically
Because the method example($str1) is not static, you need to call it by instance.
I think you are calling other instance's methods in example, so the simple way is call the method by instance.
$helper = new StringHelper();
$percentage = $helper->example($title);
Or you need to defined all those methods to static.
I usually use parameters like this:
public function test($parameter)
{
echo 'Parameter value: ' . $parameter;
}
While looking at laravel service container I see this code.
public function __construct(UserRepository $users)
{
$this->users = $users;
}
According to the documentation it uses reflection.But i dont understand.
I dont know how the parameter UserRepository $users works. Is that an alias or something?
This is called type-hinting and is used to inject dependencies in a constructor or to validate the right type of argument is passed to a function. The injection simply means that if the class is called with the make method, Laravel will automatically provide an instance of the class required by your constructor.
For example if you have a function public function something(string $something) it would throw an error if any other type than a String is passed to this function, making sure the right data is used.
From the laravel documentation:
Alternatively, and importantly, you may "type-hint" the dependency in the constructor of a class that is resolved by the container, including controllers, event listeners, queue jobs, middleware, and more. In practice, this is how most of your objects should be resolved by the container.
For example, you may type-hint a repository defined by your application in a controller's constructor. The repository will automatically be resolved and injected into the class:
Laravel has a great service container and it makes all dependency injections, so you don't need to pass a class a parameter, laravel do it for you.
without container you have to pass this parameter
class A {
public $foo;
public function __construct (Foo $foo){
$this->foo
}
$classA = new A((new Foo))
When laravel encounter with these classes, it resolves them.
Also you can define manually these classes using singleton() or bind() methods
$this->app->singleton('FooBar', function($app)
{
return new FooBar($app['SomethingElse']);
});
Or you may use interfaces. You can bind implemented class for to the interface and laravel when encounter with that interfance, it will resolve as you wish
$this->app->bind('App\ICacheManager', 'App\RedisManager');
public $redis;
public function __contruct(ICacheManager $redis){
$this->redis = $redis;
}
for more further check out laravel service container
I am trying to do a hello world service provider with the new Laravel 5.4.
I have created the following service provider file:
//File: app/TestProvider/TestServiceProvider.php
namespace App\TestProvider;
use Illuminate\Support\ServiceProvider;
class TestServiceProvider extends ServiceProvider
{
/**
* Register bindings in the container.
*
* #return void
*/
public function register()
{
$this->app->bind('Test', function ($app) {
return new Test();
});
}
}
I have created a simple class under the same namespace:
//File: app/TestProvider/Test.php
namespace App\TestProvider;
class Test
{
/**
* Register bindings in the container.
*
* #return void
*/
public function helloWorld()
{
echo "hello world";
}
}
The problem is, this is not registering. The register method is executing as when I put a breaker before the 'bind' method, it executes:
public function register()
{
dd("BREAKER");
$this->app->bind('Test', function ($app) {
return new Test();
});
}
So this outputs "BREAKER" as expected. However if I put the breaker in the closure, nothing happens which suggests for some reason, that 'bind' method isn't being executed??
Any ideas?
EDIT:
Just some further info: I know that the Test class is registered and in the correct namespace as I can do:
dd(new Test());
in the registration method, and it outputs the resource id as expected.
Explanation
The closure provided only runs when the binding is being resolved. That's why it's a closure, it can be saved in the service container and resolved at any time while the program runs.
Solution
To see the resolved binding, create a controller and resolve the class in that controller:
// File: app/Http/Controllers/TestController.php
namespace App\Http\Controllers;
// This isn't the best way, but it works. See the best way below
class TestController extends Controller {
public function index()
{
return \App::make('Test')->helloWorld();
}
}
Of course, don't forget to register the route:
// File: routes/web.php
Route::get('/', 'TestController#index');
The binding will resolve when you hit the homepage.
However, as I said, it's not the best way, so here I prepared a better way. Change the way you register the binding:
// File: app/Providers/TestProvider.php
namespace App\TestProvider;
use Illuminate\Support\ServiceProvider;
use App\TestProvider\Test;
// Better way
class TestServiceProvider extends ServiceProvider
{
/**
* Register bindings in the container.
*
* #return void
*/
public function register()
{
// Note: we bind the exact complete class name!
$this->app->bind(Test::class, function ($app) {
return new Test();
});
}
}
After this change the controller so that it looks like this:
namespace App\Http\Controllers;
use App\TestProvider\Test;
class TestController extends Controller {
/**
* #var Test $test
*/
private $test;
// Let Laravel resolve the dependency on constructing the class
public function __construct(Test $test)
{
$this->test = $test;
}
public function index()
{
return $this->test->helloWorld();
}
}
You will see that the exact same thing happens, but it looks more elegant and avoids conflicts.
Details
Laravel gives only a high level overview of the service container, which doesn't help to learn how it works on the inside. The best way to see that is to go down the call stack.
When you do that, you find that Laravel registers every class in the project in the service container. That means that whether you create a service provider or not, the class will be in the container. How exactly?
When you run php artisan optimize, Laravel creates files that have array with all the classes of the project. When you run the app, after registering everything from the service providers, Laravel registers the rest of the classes from that file.
That means that in your case, if you don't specifically register the Test class, it will still be resolvable. Basically, you only need to register classes that need some specific instructions to be resolved.
So how does Laravel resolve the dependencies?
When you run \App::make(Test::class) or inject dependency via type hinting in the constructor (the "better way" from my solution), Laravel looks for that dependency among the bindings.
When it finds the dependency, it resolves either the closure associated to it or the constructor of the class directly.
When it resolves the constructor directly, it looks for type hints among the constructor parameters and recursively resolves all of them until there's nothing else to resolve.
After that it returns the resolved class.
Of course, bear in mind that for Laravel to analyze the contructor of a class, it needs to be resolved via the service container in the first place. You can't just call $test = new Test(); and expect Laravel to do all the magic :)
Conclusion
This is a rather quick overview of Laravel's service container. The best way for you to learn it is, of course, studying the sources for yourself. It's truly elegant and it uses PHP's functionality to the fullest.
I really hope this shed some light on the service container for you and can help you in the future :)
The closure passed to the bind() method is not executed until you actually attempt to resolve the alias you are binding.
So, if you dd('breaker') inside the closure, this won't actually get executed until Test is resolved (whatever your preferred resolution method is):
Service provider:
// bind the closure to the 'Test' alias
public function register()
{
$this->app->bind('Test', function ($app) {
dd("BREAKER");
return new Test();
});
}
Code that resolve Test alias:
// different ways of resolving the alias out of the container.
// any of these will execute the bound closure.
$test = resolve('Test');
$test = app('Test');
$test = app()->make('Test');
$test = \App::make('Test');
try:
$this->app->bind(Test::class, function ($app) {
return new Test();
});
I'm aware that methods can be resolved automatically by Laravel within the controller:
//A
class ScriptsController extends Controller {
public function __construct(Script $scripts){ // Script automatically injected
$this->scripts = $scripts;
}
public function store(Request $request, $id){ // Request automatically injected
// do something
}
}
I simply want to do the same thing with any class or method.
// B1
class MyClass extends Controller {
public function __construct(Bar $bar){ // Bar to be automatically injected
$this->bar = $bar;
}
public function doSomething(Foo $foo, $id){ // Foo to be automatically injected
$foo->do();
}
}
Then somewhere else
// B2
$class = new MyClass(); // without an error
$class2 = new MyClass();
$class2->doSomething(); // ditto
There are tutorials about this but rather than answering this directly they tend to have long explanations about how the service provider works etc.
Is there a simple way to add a line somewhere ( Bind perhaps ?) to have the container resolve the dependencies so that B2 above works?
I don't think you'd be able to do that with that particular syntax. You can have Laravel automatically inject dependencies for your class, but you'd need to resolve it out of the container in any case.
Please see the documentation here for binding: https://laravel.com/docs/5.3/container#binding and further down, resolving classes from the container.